Page II: Weather and Climate Report - Last updated March 11, 2017
Written by Sig Silber
This Page contains expanded versions of graphics that auto-update plus scientific information that was first published in a weekly version of the GEI Weather and Climate Report.
In general, text information that updates is not updated on this Page but can be found by looking at the last five weeks of the weekly version of the Weather and Climate Report and the index to those is
The cycle through the month is that the Monday Report after the Third Thursday contains the analysis of the NOAA Seasonal Update. the Monday after the last day of the month includes the analysis of the NOAA update of the early version of the following month. Australia reports every two weeks so their update report is either in the current week's edition of the GEI Weather and Climate Report on the previouis weeks edition. On weeks when NOAA is not releasing major new updates, there is often a science theme in the GEI Weather and Climate Report for that week.
We are going to this new approach as trying to maintain this page up to date on information that changes but does not auto-update has become very difficult. So look here for information that auto-updates and scientific discussions which appeared in prior editions. For current discussions of seasonal outlooks etc, please refer to the five most recent GEI Reports and you will find that information there.
TABLE OF CONTENTS
Note: Graphics in this report are auto-updated by NOAA (National Oceanic and Atmospheric Administration and the various weather organizations within NOAA as it is a complex organization) and other sources. The commentary from Econointersect is updated once or twice a week and may lag the graphics updates.
Current Through Seven Day U.S. Weather Maps.
Let's start by looking at the enhance infrared satellite imagery. This graphic updates every six hours. The time used is ZULU which in some places is called Greenwich Mean Time (GMT) or UTC. Here is a ZULU to normal time converter. Where I live I just subtract six hours (not worrying about the one hour that Daylight Savings or Standard Time changes that formula) which means that 10 pm my time shows up as 4 am ZULU with tomorrow's date so one has to be careful in how to interpret the time stamp.
Let's take a look at the weather fronts. Here is a national animation of weather front and precipitation forecasts with four six hour updates and a second day of two 12 hour updates the second of which is intended to provide coverage out to 60 hours. Beyond 48 hours, additional maps are available at the link provided above.
The explanation for the coding used in these maps, i.e. the full legend, can be found here although it includes some symbols that are no longer shown in the graphic because they are implement by color coding.
And here is pretty much the same information with interpretation and a focus on tropical storms. It does not cover as wide an area e.g. it does not cover the Western Pacific or the Atlantic far east of the U.S.
There is always the possibility that the outer circulation can enter the circulation of a High or Low over CONUS and provide moisture to that feature. This is a useful diagram attributable to Kelvinsong.
Here is a broader view of projected tropical hazards and benefits over an approximately two week period. There are two views. One is more focused on the Pacific and one that includes the Indian Ocean and covers Asia more completely. Both graphics auto-update on Fridays. More information can be found here. The discussion at that link there may update on Tuesdays. I am not sure. Looking at the first graphic, there is no indication of sustained Monsoonal activity in the U.S. The wet area is the Gulf of Mexico. As I have indicated, we seem to be cycling through wet and dry periods caused by tropical storms off the coast of Mexico which are in some cases providing a flow of moist air into CONUS which impacts the Southeast and sometimes a much wider area.
This graphic covers a larger part of the world. You see more activity over by Asia.
Here is a better look at the Western Pacific.
Sometimes it is useful to take a look at the location of the Jet Stream or Jet Streams.
Moisture imagery is also a very useful thing to monitor as generally speaking you can not have precipitaiton without moisture and pretty much you needs clouds present or soon to be formed.
Here is a Navy version
Not all moisture converts to precipitation. Based on my Weather Modification research, for the Rocky Mountain States the generally accepted numbers are that about 20% of moisture forms clouds and about 30% of the water in clouds falls as precipitation. So (0.2)X(0.3) is 0.06 or about 6% of the moisture passing over these states ends up as precipitation. I have no idea what the numbers are for states that do not have mountains. One thing is for sure, there is usually a lot of moisture in the atmosphere and that is not going to change due to Global Warming or at least it is not going to decline.
It is useful to understand what is going on with the jet stream.
And sometimes the Jet Stream forecast is revealing. This is the forecast out five days.
To see it in animation, click here. At the time this article was published the animation shows a tendency for there to be a Southern Branch of the Polar Jet Stream in addition to the usual Northern Branch. It can bring storms further south than usual.
This longer animation shows how the jet stream is crossing the Pacific and when it reaches the U.S. West Coast is going every which way.
Here is a very flexible computer graphic. You can adjust what is being displayed by clicking on "earth" adjusting the parameters and then clicking again on "earth" to remove the menu. Right now it is set up to show the 500 hPa wind patterns which is the main way of looking at synoptic weather patterns. .
U.S. 3 Day to 7 Day Forecasts
You can enlarge the below daily (days 3 - 7) weather maps by clicking here.
And below is a another view which highlights the highs and the lows re air pressure which in theory it should be the same as the Day-3 day or 6-day map above but it may not be identical because it may have been issued slightly earlier or later than the above maps and may have been prepared by a different meteorological team. It should be pretty close and is easy to read.
Here is the forecasted pattern of Highs and Lows three days out.
And here is six days out:
This next map is the mid-atmosphere 7-Day chart rather than the surface highs and lows and weather features. In some cases it provides a clearer less confusing picture as it shows the major pressure gradients.
Because "Thickness Lines" are shown by those green lines on this graphic it is a good place to define "Thickness" and its uses. You can find a full uk.sci.weather style explanation (thorough) at that link or just remember that Thickness measures the virtual temperature plus moisture content) of the lower atmosphere and is very useful especially in the winter at identifying areas prone to snow and in the summer areas which are going to be hot and humid. Here is a U.S. style explanation of "Thickness" by Jeff Haby who is a valuable source of Haby Hints for anyone who wants an explanation of a meteorological term. The thickness lines do not yet indicate winter conditions which might be thickness levels below 540 for most areas. The above uk.sci.weather link is is an explanation for the U.K. The levels for CONUS might be slightly different. Obviously these thickness lines do not tell you about mountain peaks. The particular definition of "thickness" on this graphic may not be the best way to define the snow line and this is discussed in the link provided but it is I believe the older method and gives a first approximation which can be further refined as per the discussion in the link. This graphic indicates normal west to east movement of air masses for the most part except along the coasts.
The following table is useful but designed for Europe. I was not able to find the corresponding information for the U.S. but it would not be drastically different. In the U.S., the last zero is dropped off the Thickness Level so where it says 5640 that would show as 564 in the U.S. Also remember the temperatures shown are in Centigrade. So 580 would correspond to about 80F in full sunshine during the summer. That is why I say the 582 and 576 thickness levels are a bit unusual for mid to late October.
(6 - 10 and 8 to 14 day) Forecasts
Note: This is a forecast for six days from when it is issued.
When I provide comments, they apply to the forecast issued on the most recent Monday. Please note these maps auto update daily and on weekends they are generally issued without review or discussion by the NOAA meteorological team.
1. Temperature Forecast for days 6 - 10:
2. 6 - 10 Day Precipitation Forecast:
And now what they call Week Two which is days 8 - 14. Notice the overlap of days 8, 9, and 10. This reflects the difficulty of precisely timing the movement of highs (ridges) and lows (troughs) which is the primary mechanism for the development of these forecasts especially during the winter when these patterns tend to move from west to east.
3. The 8 - 14 Day (Second Week) Temperature Forecast:
4. The 8- 14 Day Precipitation Forecast:
In theory the week one forecast each week should be what was forecast as week two the prior week. You can track the ability of NOAA to predict things by looking at the prior week's forecast.
At this point I think it might be useful to mention the different procedures used by NOAA to make the 6 - 14 day Outlooks and the Monthly, Seasonal and Long-Term Outlooks. The shorter the outlook, the more NOAA depends on current weather patterns and the models basically extrapolate out the current weather patterns and to a large extent rely on the analogs that I discuss below. High frequency cycles such as the MJO, PNA, OA, NAO are a factor and you can learn more about them elsewhere in this Report. When similar weather patterns occurred in the past, what did the next 6 - 10 days look like? That is the basis for using analogs and the driver of weather forecasting models. So the short-term Outlooks do not depend very much on assumptions about medium- and low- frequency (slow changing) cycles such as ENSO and the Pacific i.e. the phase of the PDO. To a large extent NOAA ignores the AMO in their forecasting. Those medium- and low-frequency cycles might be reflected in the analogs and I try to tease them out each Monday in my analysis of the Analogs issued with the the 6 -10 Day Outlook for that Monday.
The further out you go, the less the Outlook depends on current weather patterns and the more it depends on medium- and low frequency-cycles and statistical trends. So the preliminary Outlook for the following month issued with the seasonal outlook may actually use a different methodology in its preparation than the updated Outlook for the following month issued on the last day of the preceding month because the updated Outlook for the following month will have 14 days of the Outlook created by a more reliable method and is less dependent on general assumptions. I do not want to make too much about this as often there is not much difference between the preliminary Outlook for the following month and the updated Outlook for the following month issued on the last day of the month. But sometimes it changes and the above explanation is part of the reason for that. It is a sensible approach.
Current (or upcoming) Month Forecast.
Long Range Forecasts
If you want larger versions of each map (temperature and precipitation) you can find them here. And each of those maps can be clicked on to further enlarge them.
These folks look at this from a very detailed perspective.
Recent El Nino Impacts
Weather Pattern Impacts (very likely related to El Nino)
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
Below are snapshots of 30 Day temperature and precipitation departures over the life of this El Nino. The end date of the 30 day period is shown in the graphic. It is a way of seeing how the impacts of this El Nino of unfolded.
Recent Impacts of Weather Mostly El Nino but possibly Also PDO and AMO Impacts.
Below are snapshots of 30 Day temperature and precipitation departures over the life of this El Nino. The end date of the 30 day period is shown in the graphic. It is a way of seeing how the impacts of this El Nino have unfolded.
Lets take a look at the combined results for the first three months of 2016: January, February and March.
And here is the April (30 day) graphic.
I realize this is a lot of graphics but one needs to look at the history of an event to assess it. As you can see, so far we are not having the expected El Nino Impacts in CONUS.
Here is the ninety day picture for February, March, and April.
And here is the graphic from last week which added a week and removed the seven earliest days so it is a 30 day analysis through May 7, 2016
And here is the latest 30 Day Temperature and Precipitation Departure (same as anomalies) graphic.
Here is what May looked like:
But looking at a longer time period in this 90 days or approximately three months.
And then we started to track June.
Here is the 30 day period through June 25.
Comparison with the Three Strongest El Ninos
I thought this comparison of the three strongest El Nino's since 1950 with the current El Nino would be interesting. The red numbers are El Nino values; the blue are La Nina Values. I am just show the ONI values for the three strongest El Ninos and the current one.
Obviously we do not know how this one will play out but I wanted to see if there were any clues as to which of the other three Super-El Ninos this one might most resemble.
What I see is that this one had an ONI of 0.5 or higher two months earlier than the 1997/1998 El Nino. But it has strengthened a lot faster than the 1982/1983 El Nino. Notice the 1972/1973 El Nino peaked in OND as this one most likely will also. But the PDO stayed negative during the entire duration of the 1972/1973 El Nino and the AMO also was negative. The 1982/1983 El Nino occurred during PDO+/AMO- conditions which are very favorable for the development of a traditional El Nino. The 1997/1998 El Nino occurred during PDO+ and AMO+ conditions but it was true PDO+ and not induced by the El Nino which most likely is the case with this El Nino. Also the AMO was far more positive at that time and now is close to neutral but may be reading positive during recent weeks.
So I conclude that we do not have a good model. The NOAA analogs are totally inconsistent with regards to suggesting that current conditions are reminiscent of past conditions. So we have little to go on. And yet NOAA and JAMSTEC are certain they know what the impacts will be. It is good to have confidence even if your basis for that confidence may make no sense.
Perhaps I should have shown 2014 also as it was close be recording as an El Nino which was not the case for the other three which were not immediately preceded by what was almost an El Nino. That is another reason why I have basically zero faith in the NOAA and JAMSTEC forecasts. To me this is uncharted territory.
A helpful person provided me with this graphic. The maps are (from left to right and row to row downward) in declining strength of the El Nino.
You can get a larger image here. You probably also get a larger image by just clicking on the graphic. It may required doing that twice.
I will now attempt to dissect this set of data a bit. My choice of the three areas to categorize was arbitrary. The analysis could be done state by state and actually in some cases the impact was in a part of a state. I picked three areas that are often discussed re the impact of an El Nino. I could have added Arizona and I could have added the Northwest above California and other parts of CONUS as well. Where I thought the impact of a particular El Nino was small or highly variable within the regional category, I did not include it in that category.
The breakdown of El Ninos into Traditional and El Nino is based on the data I have obtained from various articles so there can be some debate whether I have gotten it correct for every single El Nino. The 1953/1954 El Nino is not even recorded as an El Nino by the Japanese but I put it into the Traditional Column for no good reason, but I had to put it somewhere. I wanted to see if the condition of the two major ocean cycles was important. The condition of the PDO and AMO in the table below is my interpretation as the Index varies from month to month and thus is not always of the same sign throughout every El Nino, so it is my interpretation of the predominant condition of the PDO and AMO for each particular El Nino.
This is a first attempt at this sort of analysis so it is not professional paper grade and has not been peer reviewed. I am open to all comments on the analysis. The maps are above so anyone can do their own analysis.
Okay, here is what I came up with.
And then I tabulated the above. I have highlight in large bold type those data elements I considered most significant.
Here are my conclusions:
How about La Nina?
Importance of the Strength of the La Nina
In many ways the ENSO Cycle has impacts like the PDO Cycle. So to some extent the intensity of a La Nina determines the impacts. That is why it is important to think about how intense this La Nina might be. Here is a graphic that shows the impacts of recent intense La Nina's on CONUS.
It is useful to look at the Phases of the PDO and AMO during these three months of each of the these major La Ninas.
Let us not Forget the Atlantic.
I call your attention to the Atlantic and the warm area called the MDR or Main Development Area.
It has not worked out as forecast as the MDR is above average SSTs not below average SST's.
Compariso with 1997/1998 El Nino
And I think it is useful to take a look at the 1997 second half of the year impacts of the 1997/1998 Super El Nino.
Notice the impacts on CONUS precipitation might have been different than one might have expected. This graphic and the OLR graphic are very related. This measures precipitation the OLR measures clouds which are fairly well correlated.
El Nino in the News
El Nino may impact Brazil. This is one of many articles on this topic. Brazil is a large nation with different climate zones and a complex pattern of where crops are grown. So the exact impacts by crop are difficult to predict.
2 typhoons over Pacific: 1 could strike Japan, clip Philippines, Taiwan: CNN read more here
2015 US Fall Forecast: Fire Danger to Worsen in West; September May Yield Tropical Impact in South Accuweather here [Editors Note: Accurate but Quite an Interesting Twist]
The major impact of El Nno so far has been on Indonesia and here is a distressing article on that.
Asia-Pacific Region: El Niño Snapshot - August 2015 more here.
I found this map from that article which was produced by the UN to be quite interesting. It illustrates how in some cases the impacts are organized by layers that relate to the distance from the Equator. Every El Nino is different and I am not sure if the Phillippines are suffering from drought right now.
Forecast of a 2015 “Godzilla El Niño” Threatens the Global Coffee Community more here.
El Niño Could Be Among Strongest on Record, Raising Risk of Floods Read more here.
As El Nino looms, cloud seeding gets tailwind. Read more here.
This article on Arctic Ice Melt is interesting but to me the graphic is even more interesting.
It shows the impact of the unusual strength and positioning of the Aleutian Low. looking at the 1972/1973 El Nino and the 1982/1982 El Nino and the 1997/1998 El Nino one sees some very interesting differences. I do not see much of a trend in the high temperature peaks with this winter being an outlier and probably due to the position and strength of the Aleutian Low. One may see a trend in the low temperatures but this may be related to the PDO.
Heat makes precipitation.
Adaptation to El Nino in Indonesia Not a new paper but very interesting.
The Hot and Wet in India article might fit in this category. It is hard to separate out Global Warming from normal climate cycles unless you are a Climate Change Alarmist in which case it is all very clear to you or a CC Denier in which case it also is totally clear to you. Since I do not fit in either category I am left with the very difficult task of trying to sort it out. It is a bit like trying to sort out every medical condition from aging. We know that aging increases the odds of adverse medical conditions. But not all adverse medical conditions are attributable to age. This can become a problem what a doctor tells you are too young to have the symptoms you report or alternatively one dismisses certain symptoms as being simply age catching up with you when there is something not age related or only marginally age related going on. It is better to look at the evidence than start with a predetermined answer.
How Weather Shocks can Cause Severe Food Impacts I have not read this article yet but it looks very interesting.
Global Warming in the News
The first article in the El Nino News Section could also fall in this category.
Worldwide Precipitation Outlook
The Australian Queensland Bureau of Meteorology uses the SOI to make a worldwide precipitation forecast and here it is. It is interesting because it is based on just one variable: the air pressure differential between Tahiti and Darwin Australia.
You can read about it here and find updated maps here as they do not autoupdate. I have not researched the skill level of this tool and the SOI is mostly a tropical index, but I include it because it is interesting.
Here are the low-level wind anomalies. This graphic is not as compact as the graphic provided by the weekly NOAA ENSO Report (more white space) but this version auto-updates so you will always have the latest version of this Hovmoeller. As you can see, the wind gust of a several weeks ago at 160E is over and a subsequent less intense wind gust at 160W to 140W has also played out. There may be some activity starting in the Western Pacific that is just starting to show up on this graphic. Take a look over at 130E to 140E which by chance happens to be Darwin Australia one pole of the SOI Index. I think this is too far west to impact the current El Nino. We can also see some activity at 160E which is more significant and needs to be monitored.
Here is another graphic that is less compact than the prettied up version published by NOAA on Mondays but which has the advantage of auto-updating. You can see how the convection pattern (really cloud tops has in May shifted to the East from a Date Line (180) Modoki pattern to a 170W to 120W Traditional/Canonical El Nino Pattern. But the signs of an El Nino are getting quite faint and shifting to the west.
Let us now take a look at the progress of the Kevin wave which is the key to the situation.
And here is one more way of looking at the situation. I like this Hovmoeller a lot and I have now been able to find a version that autoupdates but is not prettied up. I will take the auto-update feature. You can see the Kelvin Wave that got started in February which started this Warm Event. There have been earlier such events that proved to be not very strong. But if you look at the bottom of the Hovmoeller which represents the current situation, you can see that this latest Kelvin Wave is moving to the East fairly rapidly and we will see the impact of that on declining ONI estimates fairly soon. The main impact of this Kelvin Wave is already East of 170 West the westernmost extension of the Nino 3.4 region. It has moved throught 30 degrees of longitude in about six weeks so perhaps next week in my weekly report I will attempt to projects its progression in the months ahead.
You can see below in the graphic which shows temperature along the Equator as a function of depth, both the magnitude of the anomalies and their size. You can now see where 2C (anomaly) water is impacting the area where the ONI is measured i.e. 170W to 120W. The 2C anomaly now extends to about 140W and the blips visible further to the west are no longer evident. The subsurface warm water appears to be making its way to the surface to some extent. This will be apparent when we discuss the TAO/TRITON graphic and my crude estimation of the ONI value that that I develop from that graphic.
The big issue is where will the +6C anomaly water go as it reaches the beaches of Ecuador? To the extent it surfaces it can create convection and impact the Walker Circulation which could then provide positive feedback to this El Nino. But that warm water might tend to go north or south or both. That is part of the phase out process for an El Nino and that is where we are in the life of this El Nino. It is peaking and will soon begin its decline.
The bottom half of the graphic is not that useful in terms of tracking the progress of this Warm Event as it simply shows the thermocline between warm and cool water which pretty much looks like this as shown here during a Warm Event except now the cooler water is not making it to the surface to the east along the coast of Equator.
In the upper graphic, notice the boundary of the 1.5C plus water temperature anomaly (which is now the 1.0C plus water temperature anomaly) is now close to 170W and moving towards the East. That is why I believe the ONI will soon peak and begin to decline. We shall see. There could be another Kelvin Wave forming and there is the issue of how the Walker Circulation might extend the life of this Warm Event. In this regard you might want to read the following post. A key graphic from that post which is a standard graphic is below.
The problem with the above graphic is that it represents the ideal case. You can see the uniform nature of the cells/loops which are areas of rising air and convection (precipitation) and areas where the warm air subsides. Where the air is rising that is an area of low pressure and where the air is subsiding those are areas of high pressure. Things always have to equalize. But the pattern is not always as shown. I believe that in the 1997 El Nino there was a giant Kelvin Circulation that extended from the Pacific to the Indian Ocean not the two cells shown above. So the general case and the variations are important. That is why it is important that we differentiate between Modokis and Traditional El Ninos which have different Walker circulations. This is a good article on the 1997 Super El Nino. I am not in any way suggesting that this El Nino is at all like the 1997/98 El Nino but simply pointing out that the details of each Warm Event are different and that we can not just group them all together and expect to make sense of things.
For my own amusement, I thought I would recalculate the ONI again as I have been doing recently. To refine my calculation I have totally changed my approach and rather than having the anomalies be the way I organized the data, I have divided the 170W to 120W ONI measuring area into five subregions and have mentally integrated what I see below and recorded that in the table I have constructed. Then I take the average of the anomalies I estimated for each of the five subregions. So now I am applying more subjectivity but it should produce a better estimate. Notice the boundary of the 1.5C plus water anomaly is now close to 170W and moving towards the East. That is why I believe the ONI will soon peak and begin to decline. But all the Meteorological Agencies in the World believe the ONI will continue higher. Could I possibly be correct? We shall see. It is not clear the extent to which the exact value of the ONI is useful in forecasting weather. There is a correlation between the strength of a Warm or Cool Event and the weather impacts. But it is not clear that the ONI or any other single index is able to be the independent variable in the forecasting model.
Here is another way of looking at it:
This Hovmoeller shows a lot of useful information. I could copy it into MSPaint and draw some lines on it but then it would not autoupdate so I do not wish to do that. But take a lot at 140E 160E, 165E, 175E, 120W and 90W. Remember reading from top to bottom one is reading the earlier times to the more current times. So you can see how this Warm Event started at 140E, has moved to 160E and then to 165E and lately you can see continued movement towards 175E, which it has now reached, but very slowly. You can also see that the entire Equator is warm. You can especially see the impact east of 90W where the Kelvin Wave is crashing into Ecuador. Also more warmer water has expanded towards 120 W. The eastern progress has been slower than I had anticipated. Leaving aside the SOI issue which until this week was no longer consistent with an El Nino, but has come to life perhaps just temporarily, this is clearly an El Nino type sea-surface temperature (SST) pattern right now. But to me it seems to be a pattern that will play out as it does not appear to be going to be reinforced. It may well play out more slowly that I have anticipated. But it is playing out.
You will not see the ONI decline until the warm water over at 175E has moved to 170W. Until then, the ONI could easily continue to rise but probably not by very much although some models are predicting it will peak at about 2.0. Once the warm surface water no longer extends west of 170W the ONI should begin to decline. I hesitate to offer a new estimate of when that will happen as I have not had the time to play those animations enough times to make an estimate. Plus it depends on the way the subsurface pod of warm water behaves and I do not know enough to predict how that will work its way through. The size of the deep water anomaly may have a bearing on the rate of movement to the east which is slower than what I read in the literature as being more usual. It may also impact where it rises. It has to go somewhere or mix or come to the surface and experience evaporative cooling. The MJO now appears to have some impact but probably small. We will watch the progress of this Warm Event together because I have provided the graphics that will allow us to do that.
I thought I would show what things look like this year compared with the most recent very powerful El Nino namely the 1996-1997-1998 period. Notice the SOI went very negative early in 1997. That is why I have concluded that if there is to be an El Nino it is likely to be a 2015/2016 El Nino not the 2014/1015 El Nino that NOAA has been advertising.
And here is the current reporting of the SOI.
View from Japan as Compared to the View from NOAA.
NOAA issued an updated Seasonal Outlook on October 15. The JAMSTEC (Japanese) analysis is also available. Let us compare them.
First let's take look at the ONI forecasts which is the most widely available measure of the strength of an El Nino (or La Nina) and is the deviation of the sea surface temperature from climatology (normal) in a small part of the Eastern Pacific along the Equator considered to be the best place to assess the strength of an ENSO phase whether it be El Nino, ENSO Neutral, or La Nina.
First the NOAA forecast of conditions in the Nino 3.4 area which defines the ONI Index:
OMG there are two different versions of the model results. There is this one:
And below is another version (and the version below is the one that NOAA shows in their weekly ENSO Report so I am assuming that it is the one that they want us to use) . I am not sure of the specifics of the difference but the results are modified in some way presumably to make them more accurate. I think it has to do with the base used to establish "Climatology" which is usually defined as conditions from 1981 - 2010 (not sure why it says 1982 - 2010). But the Equator has been experiencing a warming trend thus a thirty-year average may overstate warm anomalies. So, to me, reading the legend in the graphic below It looks like the base was adjusted to 1999 - 2000 reflecting the steady rise of temperatures in the Pacific. It is possible that there is also an adjustment for the variation in the model results for the multiple members of the ensemble but I do not know how that would work given that they still refer to the mean of the different forecasts of the members of the ensemble. So I can not tell you exactly why the model results below differ from the model results above.
It would be good if NOAA decided which approach they wanted to use and presented only one version of this graphic. But I understand their dilemma.The below graphic is probably the most useful and will agree with what is officially recorded but the above version is more consistent with what the other meteorological agencies report. I prefer the below as it is more realistic.They both show this El Nino peaks in October or November of 2015.
And here is the JAMSTEC forecast of the ONI.
Here is the discussion
But then there was this bonus discussion which is well worth reading. They do some bragging about the forecast model but it may be well deserved.
Now I will compare the two forecasts using three time periods: Short Term, Medium Range, and Long Term
SHORT TERM (December - January - February) JAMSTEC did not publish NDJ information so I am working with DJF. So we are not comparing the forecasts for November. .
Sea Surface Temperatures.
Starting with the NOAA results (and notice that they show Africa twice which can be confusing but allows Africa to be more easily considered in the context of the oceans that surround it):
And now the JAMSTEC Sea Surface Temperature Anomaly.
They look fairly similar if you can get by the garish colors used by the NOAA graphic artists which certainly emphasizes the warm water off the coast of Mexico that is creating these storms off the west coast of Mexico. I find the JAMSTEC graphics easier to look at. I am curious about the cold anomaly that NOAA shows for the Equator in the Atlantic. There also appears to be a difference with respect to the waters off of Japan with JAMSTEC projecting cool and NOAA warm. NOAA also projects both an area of cool anomaly in the South Pacific and further south a strong warm anomaly. That is an important difference.
Now let's take a look at the Temperature forecasts for that period starting with NOAA:
And then JAMSTEC:
For CONUS, JAMSTEC is forecasting that the colder than climatology area will cover a significantly larger area. NOAA does not cover the rest of the world. In the JAMSTEC map (and the discussion above which was provided by JAMSTEC) you can see that most of the world is projected to be warmer than climatology with the U.K and Scandinavia, Eastern Siberia, the Highlands of Southwest China and a small part of Argentina being the few exceptions. Given that there is Global Warming and the forecasted values are being compared to a base that may not fully reflect the warming which has occurred, any cold anomalies are especially significant.
Now let us look at Precipitation again starting with the NOAA map.
And here is the JAMSTEC Precipitation Map.
The NOAA forecast and JAMSTEC forecast are pretty similar for that period with regards to CONUS but JAMSTEC extends the wet area into the Northwest but the outlook for Alaska differs between the two forecasts. Interesting features of the JAMSTEC map outside of CONUS include dry conditions in Central and Northern Brazil, Central America, parts of Canada, parts of Australia and New Zealand, Iran, Afghanistan, South Africa and the Mediterranean. The dry area for India is no longer shown.
MIDRANGE (March - April - May)
Starting with Sea Surface Temperature Anomalies and beginning with NOAA:
And then JAMSTEC:
JAMSTEC is still showing El Nino into 2016. But it is looking a bit more Modoki-ish in terms of the severance of the connection of the warm water with the South American Coastline. Notice the less intense coloration off the Coast of Ecuador and Peru in the JAMSTEC map. But the AMO is more Negative and the PDO is more clearly defined in the JAMSTEC map. They seem to have different opinions on the ocean temperature anomalies off of the coast of West Africa but NOAA has greatly reduced their cool anomaly off of West Africa.
Now let us take a look at Temperature and again first NOAA:
And then JAMSTEC for the same three months
JAMSTEC now is more aggressive at forecasting widespread colder than climatology conditions for CONUS as compared to NOAA. JAMSTEC is showing cold for parts of Europe. Both JAMSTEC and NOAA show Alaska as still being warmer than climatology which suggests the Aleutian Low will be strong and positioned to direct warmer air over Alaska.
Now Precipitation and again staring with NOAA:
And then JAMSTEC.
JAMSTEC is showing more of a west/east split on precipitation for CONUS while NOAA is more north/south. Brazil is still dry, the rest of South America is wet. Southern Africa is still dry. Western Europe is dry while further east it is wet. Indochina is dry.
LONG RANGE (June - July - August)
First NOAA: And at this point in time this is the furthest out they go and their maps through Apr-May-Jun still shows the El Nino in place.
And then JAMSTEC:
JAMSTEC is well along to ENSO Neutral in their forecast perhaps pausing and resembling an El Nino Modoki Type II on the way. But the warm water off of the West Coast of North America continues so that it is not clear which of the two will have the most impact on North American weather. JAMSTEC is still showing PDO+ even as the pattern shifts to La Nina. That could be signifying a Climate Change in the Pacific to PDO+ and possibly also AMO- but it is too soon to tell.
Now let us look at Temperature and again starting with NOAA
And then JAMSTEC
There is a total difference for the pattern in CONUS with NOAA being warm and JAMSTEC cool extending up into parts of Canada. Again it is a warm Alaska. But in the JAMSTEC maps, Europe remains cool as well as parts of Argentina and far Eastern Siberia. China is mixed.
And finally the Precipitation forecast and again starting with NOAA:
And then JAMSTEC.
For CONUS JAMSTEC is still showing a lot of wetter areas especially in the East. Europe is a bit dry. Indonesia is wet rather than dry as was the case earlier as in this time frame the El Nino transforms into a La Nina.
The main conclusions relate to temperature and precipitation. I can only compare the two for CONUS and Alaska, but I can also comment on what JAMSTEC is projecting for the rest of the World which I have done for the three time frames: near-term, medium range, and long term. The ONI forecasts are similar but the translation into air temperature and precipitation for CONUS and Alaska are somewhat different NOAA versus JAMSTEC especially further out in time. A few general conclusions are that:
Looking Ahead to the Winter of 2016/2017
Repeating from the NOAA Discussion:
It is not a perfect procedure but I took a look at the ONI values for the Oct - Nov - Dec three-month period starting in 1950. I used an ONI of 0.5 or higher as an indication that it was a warm event and possibly an El Nino although it takes more than one three-month period of an ONI of 0.5 or higher to define an El Nino. Similarly, I took -0.5 or more negative to indicate La Nina conditions during that three-month period. Then I tabulated the number of times that there was a +0.5 or greater in one year followed by a -0.5 or more negative in the following year.
My tabulation was nine times "no" and ten times "yes". On two occasions there were two years of 0.5 or more then followed by a year with -0.5 or less. Not shown is the value for 2010 which was -1.3 which is one of the ten times that there was this year to year dramatic change. So I concluded that there is a 50% chance of a La Nina in the winter of 2016/2017 on a statistical basis alone. However my general feeling is that the winter of 2016/2017 is most likely to be ENSO Neutral.
To examine this question more carefully, I prepared the below table where I show what I know about the ten years where the ONI changed dramatically from positive to negative. I show what I know about the warm event which in most cases was an El Nino of some sort and I show the PDO and AMO with the sign/phase in the year shown followed after a comma by the sign/phase in the following year. It is not conclusive but I do not see the current pattern of PDO+ and AMO+ or Neutral represented in this table except in 1997 and probably also in 1987. I do not expect the PDO to be negative next year so that kind of invalidates the 1997 case as being predictive. 1987 was a Modoki and this now is a pretty much traditional El Nno so I do not believe the 1987 case is particularly predictive. Thus I conclude that the winter of 2016/2017 being a La Nina is less than 50%. If you knew nothing you might assign a probability of 25% for a La Nina year. Given that this winter will be an El Nino, you might assign a probability of 33% to the following year being a La Nina. It is like a box of one red, one blue and two white balls. If you draw from that box, the probability of a red ball is 25%. If you remove the blue ball because you just had an El Nino winter, the Markovian probability of a red ball increases to 33%. I think this is how Australia looks at things. But ENSO is not a four-year cycle but more like a 5 to 7 year cycle. So we could try to be more fancy but the results may not be better.
I have no data on the 1953/54 El Nino and I do not know why but it appears not to have been recognized by Japan. So I do not know if we are dealing with half the events being Modokis are more than half. The reason that might be important is that a Modoki is closer to being a La Nina than a traditional/canonical El Nino as the warm water is not as far east. So it might be easier for a Modoki to convert to a La Nina except some Modokis transform into traditional El Ninos which just happened. The 2014/2015 Warm Event was probably best described as a Near Modoki Type II that has now transformed itself into a traditional but late in the season El Nino. Obviously we have more to learn.
Air Pressure and Wind Related Cycles.
Air Pressure Cycles.
Arctic Oscillation (AO) and North Atlantic Oscillation (NAO). Basically both the AO and the NAO relate to the differential between mid-latitude and high latitude atmospheric pressure. The NAO is a bit easier to define as there are two semi-permanent features: the Icelandic Low and the Azores High sometimes called the Bermuda High. But still there are at least three different ways of measuring the NAO. I am not sure how and exactly where the AO is measured, but in both the AO and NAO a positive index indicates the differential between the mid latitude highs and the Arctic air pressure are larger than usual and a negative index means the opposite. The following table is my interpretation of the impacts of the AO and NAO but one needs to understand that these are two atmospheric factors (and thus somewhat independent of sea surface temperatures SST but that is not totally clear) which interact with many other factors so please view the following table as potential tendencies rather than a hard and fast prediction tool and also a work in progress.
Here is a NOAA graphic that I modified (made horizontal rather than vertical) to show the impact of the Arctic Oscillation. The North Atlantic Oscillation's impact is similar but further east. It is not clear if these are two separate patterns or two parts of the same pattern as they are not perfectly correlated but they do represent somewhat the same situation.
Without having yet performed a careful analysis, it would appear that a negative AO or NAO or both present a negative factor for the economies of the nations impacted.
Are the AO and NAO and ENSO Related?
Both the Tropics and the Aleutian Low have a major bearing on the weather of the Lower 48 States. Here is a good reference on the topic and this is Part II of that article. The Aleutian Low S.N. Rodionov, N.A. Bond, J.E. Overland
Let us start with a more conventional map. Welcome to Beringia. Learn more here. Also, all of Beringia is on the North American tectonic plate, as possibly is most of Japan although that is a bit controversial.
Now that you understand the part of the World I am talking about, the following climate-oriented graphic is of interest. The Aleutian Low is a semi-permanent weather feature most prominent in the winter. This graphic represents the mean (average) pattern of the Aleutian Low.
Notice the ridge (the circle in the lower right of the graphic) off the West Coast which IMO is the RRR (Ridiculously Resilient Ridge). Also remember that low pressure areas (such as the Aleutian Low) in the Northern Hemisphere rotate counter-clockwise so the position of the Aleutian Low determines:
My major interest in this weekly report is to examine how the Aleutian Low impacts weather in the Lower 48. I am by no means an expert on this subject but I am doing my best to provide excerpts from the above two articles (which I believe are two of the best articles on this subject) and to provide some explanation that might help the reader understand what is in those two articles. It is a difficult topic and at this point not completely understood.
Compare the above which is the average condition of the Aleutian Low to the Day 3 Forecast.
I apologize for not being able to find a current map: this is the Day 3 forecast but none of the current maps that I could find showed this large an area. Time flies so a Day 3 forecast works just fine. This graphic auto-updates so you will have to related the current (Day 3 conditions) at the time you read this information with the information provided below.
Here is some more information that I have extracted from the two linked articles (both from the same authors). They are perhaps difficult a bit difficult to read but you can find slightly more readable versions of these graphics at the above links. These are low resolution graphics and unless I had decided to wait and write the author and ask if he would send me some higher resolution versions, we have to work with these and I do think they are adequate for our discussion.
Let us start by considering what is considered the stronger Aleutian Lows which means lower Sea Level Pressure at the center and perhaps some other factors such as the area with low Sea Level Pressure (SLP). Notice the storm track.
And then there are the years with a weak Aleutian Low. Notice the split low with two parts both generally weaker than a single low-pressure system and notice the quite prominent high pressure ridge off the coast of the U.S. Lower 48 States. Also notice the storm track which is interrupted and then reforms.
First the information for the W1 Type
Notice the Aleutian Low is shifted way to the west and the RRR is very pronounced. Also notice the storm track and the absence of significant storm activity one the eastern side of the Pacific in Beringia. Also, with W1 you can see how Bering Strait ice would be melted. I am not going to bore you, but there are special challenges when working with spherical coordinates versus Cartesian coordinates. In theory I am a mathematician and I have to say the discussion of this in the papers is fascinating but not relevant to our discussion.
Then the C1 Type.
Notice the split Aleutian Low and the really pronounced RRR. Also notice the storm track.
The following table relates to Figures 3 and 4 i.e. the winter analysis not the W1/C1 analysis.
In this table I did not use a smoothing algorithm for the AMO and PDO but instead simply recorded their condition as per their associated index for the four- month winter season. I am assuming and fairly certain that the years provided by the author are the year starting in January of the Nov/Dec/Jan/Feb period used to categorize the Aleutian Low as being one of the ten strongest or weakest since 1944 which was a climate shift in the Pacific i.e. the Pacific Decadal Oscillation changed signs.
Curiously this relationship did not apply prior to 1922 so that remains a mystery.
Also of interest, since 1900 the first year in the above graphic, the NP Index appears to be trending lower meaning the Aleutian Lows are getting stronger. Is this Global Warming? The length of the trend suggests that it might be but still one can not explain the lack of the more recent correlation between the NP and PDO during the period 1900 to 1922. Also curiously there appears to be no current measurements of the NP index or ALP index at least that I could find so one wonders if NOAA has access to this data in their computer models.
Japan Bonin High
This article might explain it. From the Summary.
We have talked before about semipermanent Highs and Lows but one can never talk about it enough as these are so very important. Here is a K - 12 write up that keeps it simple.
CONUS during the winter of 2015/2016 has been most impacted in the West by the Aleutian Low and the Pacific High and in the East, the Icelandic Low and Bermuda High have also played a role. I want to focus on the Aleutian Low and the Pacific High which some call the North Pacific High and I call the Eastern Pacific Subtropical High (EPSH) because there is another High at the western end of the Pacific (actually two: the WPSH and Summer Okhotsk High).
Here is a good water vapor image of the Aleutian Low.
During the winter 0f 2015/2016 the Aleutian Low has been very strong but generally centered further west and north than is usual for an El Nino. At the same time, the Pacific High - which derisively is referred to as the Ridiculously Resilient Ridge (RRR) - has been further north than one would expect and thus valiantly protected the Western Coast of CONUS from Pacific storms. Thus we had a northerly displaced El Nino impact.
Of great interest is the topic of whether the changes in these features are cyclical (for periods of time one way and then for periods of time the opposite way) or secular (gradually changing in a particular direction) i.e. due to Global Warming. It is difficult to tell (and even more difficult to know if one is being scammed by those who do the studies) since ... oh well, no need to pull back the curtain and reveal how science is really conducted. It is better to maintain the illusion that scientists are objective and fully qualified to perform their research. Most are and if I provide links to articles or discuss articles, and if I do not say differently, you can assume that I have concluded that these are real scientific papers not commissioned papers and they have been written by qualified researchers.
A way of looking at things is that if you see a change in the Eastern Pacific you wonder if there has been a corresponding change in the Western Pacific. Here are two links to essentially the same paper on this so if you are interested please click here or here. One or the other may load and print more easily on your computer. I notice when I read that paper and the list of references that they seemed to be talking about the 1976 - 77 Pacific Climate Shift. So I conclude this is all probably mostly part of the PDO Cycle. A way to verify that would be to see if the changes discussed in this article (two links to the essentially the same article) have reversed now that the PDO seems to be shifting again to the same phase as what occurred in 1976-1977. That phase reversed in 1998.
Monsoons are seasonal changes in the prevailing wind direction caused by the changing differential between land and ocean temperatures during various seasons and there are usually associated changes in the location and strength of High and Low Pressures Systems.
North American Monsoon (NAM)
What is the North American Monsoon. There are many resources for understand the North American Monsoon but I found these graphics from this University of Arizona report to be very useful.
How does it come on?
The North American Monsoon affects Mexico and the the southern tier of the U.S. mostly Arizona and New Mexico but it can impact states to the north and to the Northeast of Arizona and New Mexico thus it has a significant impact in the summer over the entire Southwest and even the Plains States.
And in term of how El Nino and Pacific and other factors impact the North American Monsoon (NAM), this from a presentation on the Albuquerque NM Weather Service web site may be helpful.
Click here for a larger Image.
And here is what we were looking for in June as a precursor to the development of the North American Monsoon. A nice big high pressure center in Northern Mexico heating up the land.
Seasonal Distribution of Precipitation during the Monsoon
Similar patterns are characteristic of other monsoons around the world which are generally based on the land warming and thus impacting the direction of prevailing winds.
Some may find this article on Northern Hemisphere Monsoons to be of interest.
Multidecadal to multicentury scale collapses of Northern Hemisphere monsoons over the past millennium Yemane Asmerom and Victor J. Polyak Department of Earth and Planetary Sciences, University of New Mexico, Albuquerque, NM 87131; Jessica B. T. Rasmussen Leander Independent School District, Leander, TX 78646; Stephen J. Burns Department of Geosciences, University of Massachusetts, Amherst, MA 01003 and Matthew Lachniet Department of Geoscience, University of Nevada, Las Vegas, NV 89154
The abstract is of interest.
This may be new information to some. Warmer is wetter, cooler is drier.
The methodology of this research is interesting. Stalagmite BC-11 was collected in 2004 from Bat Cave, a room in Carlsbad Cavern, New Mexico. There was a second stalagmite labeled BC2 assessed also but since it had been broken off (circa 1923 AD and may have been compromised) was considered to be a bit less reliable and the thickness of the layers were calibrated to tree ring data. The thickness of the bands was used to estimate the annual precipitation which in that area is mostly Monsoonal. Apparently the research team were able to determine the source of the precipitation i.e. the Pacific (mostly winter) versus Gulf of California and Gulf of Mexico (mostly Monsoon).
You might find this graphic of interest.
There is much that is interesting in the stalagmite (I keep them separate by associating the "g" in stalagmite with growing from the ground and the "c" in stalactite as growing from the ceiling) analysis paper. It provides a basis for thinking about droughts that are longer than can be attributed to phases of the AMO and PDO. Such droughts may well tend to occur Worldwide (bad news re thinking that food deficits in one area can be made up elsewhere) and they tend to be associated with cold SST's not warm SST's. Talk about "an inconvenient truth". I doubt that the political establishment offers refunds for the dissemination of incorrect information.
The IPCC Climate Change models seem to agree that in the future all the Monsoons will be wetter except the North American Monsoon. The North American Monsoon is an outlier relative to the IPCC AR5 WGI Report. It is projected to be weaker. This paper raises questions on that re the historical record. But the North American Monsoon is a strange Monsoon as the actually monsoon is located in the Sonoran Area of Mexico. The U.S. is just on the edge of this monsoon. So the Monsoon itself could be stronger but the Impact on the U.S. Southwest might not be stronger. However this study suggests that in the Guadalupe Mountains of Southeast New Mexico, the North American Monsoon was stronger when it was warmer. This actually makes sense when you realize how monsoons work. But the Guadalupe Mountains are not the entire Southwest. So by itself it does not tell the full picture but it is pretty suggestive. It is also important to recognize that the North American Monsoon, sometimes called the Southwest Monsoon, or the Arizona Monsoon, impacts many CONUS states not just the states in the Southwest. So there are many variables including start and end dates, extent of impact beyond the Southwest, and the split of impact between Arizona and New Mexico.
Other than Tropical Storms, the major feature impacting CONUS in the Summer is the Southwest Monsoon or North American Monsoon if you prefer.
Here is a very good paper that explain the U.S. Monsoon.
A METHOD FOR DEFINING MONSOON ONSET AND DEMISE IN THE SOUTHWESTERN USA ANDREW W. ELLIS, ERINANNE M. SAFFELL and TIMOTHY W. HAWKINS Office of Climatology, Department of Geography, Arizona State University, Tempe, AZ 85287-0104, USA
An oddity about the recording of Monsoons is discussed in part in this paper. The follow are my comment on their analysis.
Here is a good recent paper on the evolution of the NAM. Mechanisms for the Onset and Evolution of North American Monsoon Ehsan Erfani and David L. Mitchell Desert Research Institute, Reno, Nevada University of Nevada, Reno, Nevada
It focuses on Sea Surface Temperatures (SST's) and is not a surprise. The reason for the study is interesting. NOAA was having difficulties forecasting precipitation during a Monsoon. It does raise questions about the logic of concluding that Global Warming will reduce the strength of Monsoons. The paper concludes that 29C in the Northern Gulf of California is necessary to have this Monsoon. 27.5C is the general estimate of what causes Convection but apparently the Marine Boundary Level requires 29C for what is called CIN (temperature inversion) to be surmounted. But there are other factors. One has to be creative to figure out how more convection leads to a drier Planet.
Special Topic of Most Influence on 2105 Weather Worldwide - The ENSO Cycle - Currently the now probable appearance of an El Nino - with some hints that the level of optimism might be a bit overstated.
I guess we should start by describing what ENSO is. Basically the El Nino Southern Oscillation is no more or less than:
When the warm water is shifted to the West we have what is called La Nina Conditions. When the warm water is shifted to the East we have what is called El Nino Conditions and anything in between is called ENSO Neutral. Although the Walker Circulation as it applies to the tropics in the Pacific and is usually measured by what is called the Southern Oscillation (SOI) Index is important for confirming the phases of ENSO and sustained values of -8 are associated with El Nino Conditions (and it is at that level now), the approach most used to assess ENSO conditions is to measure the Sea Surface Temperatures in four areas of the tropical pacific shown in the below graphic.
Statistics show that the temperature anomaly in the area labeled NINO 3.4 above has the highest correlation with the weather impacts we observe worldwide with the La Nina and El Nino phases of ENSO so this is the most common measure used and is called the Ocean Nino Index or ONI. More information is available here. One very interesting statement in that document is
This graphic shows the hstorical evolution of the STT Anomalites in the four measurement areas.
This is interesting to me given the excitement when the ONI exceeds 0.5. The ONI is not the only measurement of interest and some say it is not the best but it is the one most widely utilized.
The first graphic below shows the most recent runs of the tool used to predict which phase of ENSO (El Nino Southern Oscillation), El Nino or La Nina, is likely in the coming months. A word on how to read this graphic. Notice there are a number of different model runs shown on that graphic and color coded. It is important to remember when looking at the forecasts of these models that getting above the 0.5 line does not make an El Nino Event but essentially creates what is called El Nino Conditions. One has to average that level for five consecutive overlapping three-month periods for an El Nino to be declared. So we are looking ahead and seeing positive signs of an El Nino coming but are not nearly able to make a definitive forecast at his point in time especially in terms of the strength of the event. Notice the ensemble mean is now substantially below 1.0 especially for the early winter months (eyeballing it it seems like a SST of 0.8 which is barely an El Nino) meaning that even those committed to there being an El Nino this winter are predicting a very weak one. Also notice the movement of the forecast mean higher into this coming summer which conflicts with the the discussion recently released by NOAA.
This second graphic is the projected sea surface temperatures. It provides a more global view of many cycles not just ENSO. The current information strongly suggests that next winter will have some characteristics associated with El Nino conditions worldwide. Notice the red area off the coast of Ecuador. That is the signature of El Nino. The warm water returning from the Western Pacific to the Coast of Ecuador. Notice this has now been updated to be a Nov/Dec/Jan map i.e. this Winter in the Northern Hemisphere. Of interest this graphic unlike the first graphic has been statistically adjusted by screens to improve the calibration of the data shown. Notice the projected continued warm water off the coast of Alaska a characteristic of a Modoki Type II and possibly a shift to a positive phase of the PDO. But keep in mind that this graphic is beyond the Spring Prediction Barrier so one has to keep that in mind as the models may well change as we move beyond Spring.
Along the Equator, by this point in time (Jan - Mar 2016) the most significant part of the warm anomaly along the Equator is predicted by NOAA to still be in El Nino mode i.e. shifted way to the east.
Notice the higher latitude anomalously warm water to some extent in the northern Pacific and to a greater extent in the eastern Pacific. To me this PDO+ pattern is more significant than the projected anomalies along the Equator.
The other maps in that series can be found here.
This shows the current condition of Sea Surface Temperatures
This version auto-updates so you can see the evolution.
To put this into animation click here. It goes fast and shows SST from two weeks ago up until I guess today or yesterday.
Here are two others in that series a one month and three month average of the prior SST data.
And here is the three-month.
Here it is as an animation showing the evolution of the recent sea surface temperature anomalies. It shows the movements better than the static graphics but you have to pay close attention and perhaps watch it over and over again. I know I do.
Here is a version that auto-updates and starts at an earlier time and goes through steps three days at a time. But you have to watch closely. Watch the El Niño dissipate and turn into a Modoki Type II. But wait.it is now in front of our eyes developing more characteristics of a Traditional El Nino. The Gulf of Mexico is interesting also.
Here is another useful too and it updates DAILY. It provides a visual representation of the Tropical Pacific both surface temperature and winds absolute and anomalies. One can see what is called the "Cold Tongue" that extends into the Tropical Equator off of Ecuador. This needs to be warmed up for there to be a Traditional El Nino and that might be happening right now.
This graphic is currently showing the favorable conditions of reduced Easterlies (see the arrows in the anomalies graphic pointing to the east) and the warm water anomaly off the coast of Peru which is supporting the development of a possible El Nino. You can find a larger version here.
This animation may provide some additional insight but it may, when you look at it, not have progressed to the current time frame. Note the dates as they flash by. They are weekly averages so you only get a more recent frame each week. This graphic shows the absolute temperatures not the anomalies. You can see the tendency for warm water to pool in the Western Pacific which in the extreme is La Nina Conditions. When it returns to the East you get what is called an El Nino. If the warm water is mostly near the Date Line it is a Modoki.
Here is a total Pacific view. Unlike the above graphic which shows the absolute temperatures, this shows the anomalies compared to average conditions. N
The following map may be helpful in understanding how ENSO works.
In the above, you can see what is called the "cold tongue" where the current coming up from Antarctica is redirected out to sea as it runs into Peru.
You can read more about it here courtesy of Wikipedia.
View from Australia
The discussion can be found here.
IOD (Indian Ocean Dipole)
The graphic comes with only a very short discussion which can be found here.
The interrelationship between the IOD and El Nino is complicated and not fully understood.
The Oceanic Niño Index (ONI) Index can be found here.
Many data resources on ENSO can be found here.
A good resource on Tropical Meteorology can be found here.
The Multivariate ENSO Index (MEI) can be found here. Some believe it is a better Index in that it covers more variables than the ONI Index.
The tradition Southern Oscillation Index or SOI Index which basically describes the pattern of convection along the Equator in the Pacific can be found here.
The formula for calculating the SOI is:
[ Pdiff - Pdiffav ] SOI = 10 ------------------- SD(Pdiff)
Pdiff = (average Tahiti MSLP for the month) - (average Darwin MSLP for the month),
Some additional information on the Troup SOI can be found here.
Strangely although -8 (El Nino) and +8 (La Nina) is the official guidelines for using the SOI levels to identify ENSO phases they sometimes use -6 and+6 for internal use within Australia as indicated in this poster.
But actually the traditional SOI Index maintained by the Australia Bureau of Meteorology is off the Equator a bit. A different index NOAA Equatorial Southern Oscillation Index maintained by NOAA is right on the Equator and it can be found here.
SOI and the Release of Ocean Heat into the Atmosphere
I thought it would be useful to review this paper by Chris R. de Freitas and John D. McLean. You can find the full paper here.
I am just going to present two figures (Figure 1 and Figure 3) from that article and discuss them. Notice on the Y Axis in both graphics the SOI goes from very negative numbers (more El Nino-ish) down to more positive numbers (more La Nina-ish).
Basically what this is showing is that the Mean Global Temperature (MGT) tends to track the Southern Oscillation Index (SOI). This makes sense because the SOI is a measure of how concentrated the Warm Pool in the Western Pacific is. When it is thicker but concentrated in a smaller area, the opportunity for evaporation and convection is less than when the Warm Pool is spread out and thinner but covers a larger area. This is the ENSO Cycle and the SOI is one of the two Indices that measure the state of the ENSO Cycle although NOAA tends to ignore it unless it confirms their wild ideas about what is an El Nino and what is not. Evaporation is the way ocean heat is transferred into the atmosphere. So the Tropical Pacific works like a battery absorbing heat from sunshine and periodically releasing heat.
This from Wikipedia might provide some additional useful information.
Thus not only does convection transfer energy from the ocean to the atmosphere, the movement of water vapor by wind transfers the location of where this happens to where the water vapor created by evaporatlon is reconverted to latent heat as cloud droplets releasing sensible heat i.e. heat that can be felt and measured by a thermometer.
But what you see in the above graphic is a discontinuity right after 1995 when there was a substantial increase in temperature. The Graph on the right (and please notice the slightly different scale on the Y Axis) shows that the relationship between the SOI and MGT resumed after a few years. Those few years are generally considered to be a Climate Shift in the Pacific and was triggered or at least occurred at the same time as the Mega-El Nino of 1997/1998.
I do not know if anyone has an explanation as to why this relationship that normally holds did not hold during a few years in the mid-nineties. But it provides a pretty good explanation of what is called the Hiatus in the increase in MGT. Elsewhere in this Report, I provide a pretty convincing case that we will soon have another Climate Shift in the Pacific and perhaps that also will come with a Mega El Nino perhaps next year or perhaps without such an event. It might again result in a stepwise increase in MGT. I would suggest that attempting to figure out why the 1997/1998 was so effective at releasing stored ocean heat, would be useful. It also would be useful if NOAA learned what a Modoki was. That is important as an El Nino Modoki does not provide as much surface area for heat transfer to the atmosphere as a Traditional/Canonical El Nino.
El Nino Modoki
Not all El Nino's are alike and in recent years the distinction between traditional or canonical (true to form) El Ninos and Central Pacific El Nino's often called El Nino Modoki has become increasingly clear. In Japan they are forecasting an El Nino morphing into an El Nino Modoki. This becomes important because the impacts of each type of El Nino on weather worldwide is very different.
This is illustrated in the following maps:
Starting with surface temperature:
Notice for the US, the Modoki results in an extreme division of the warmer versus cooler temperatures with the East very much colder than climatology. You can see the differences in Asia and other places.
And now considering precipitation
Notice that for the U.S., the Modoki results in a drier West much like a La Nina.
And below is a breakdown of precipitation anomalies from climatology by important parts of the world very impacted by the Modoki form of El Nino. You can find more information on this here.
Again the Modoki has almost the opposite impact as a Traditional El Nino in many parts of the World. It is most extreme for CONUS and Japan with the Modoki being dry and the Traditional El Nino wet.
So there is a big difference in the differential impact on weather yet BOTH WILL REGISTER AS AN EL NINO ON THE ONI INDEX.
Some think a Modoki is some sort of strange thing. To me it looks like a Modoki is simply an El Nino that did not fully make it to Ecuador or after reaching Ecuador has taken its sweet time getting all the way back to the Western Pacific Warm Pool. From a weather perspective, with a Modoki you end up with two Walker Cells. So you have a lot of precipitation in the Central Pacific. Notice how the impact on Japan and the Western U.S. varies between a Canonical El Nino and an El Nino Modoki.
Most believe the El Ninos of 2002/2003 and 2004/2005 were actually of the Modoki variety and you can see that in the winter precipitation data for New Mexico and Rio Grande Stream Flow. The below may be a Bob Tisdale compilation but it is based on the Ashok formula which is generally recognized as the way of identifying a Modoki.
The Ashok formula is EMI = [SSTA]A-0.5x[SSTA]B-0.5x[SSTA]C where the A anomaly is calculated in the region 165E -140W,10S-10N, B is 110W-70W, 15S-5N, and C is 125E-145E,10S-20N.
The 2009/2010 El Nino was also a Modoki, So you see what you read in the news may not be very useful. I do not believe that many TV and Radio station weather people (many of whom are not even meteorologists but simply actors) understand the difference between these two types of El Nino's. It is fairly recent knowledge.
First of all I want to start with the original defining of a Modoki which was publicized in a report by Ashok et al. in 2007. You can read the full report here. The definition has evolved a bit over time as Type I and Type II Modokis were later defined but I think this author is working with Ashok's original definition.
Now let us look at the impact of Modoki or not Modoki on convection.
As I mentioned these charts were prepared for a different purpose namely to examine when convection was so powerful that the clouds came close to entering the Stratosphere. But this also shows at least partially where the strongest convection activity was in the case of 8d for traditional/canonical El Nino events and in the case of 8c where convection was during Modoki events. If nothing else, this tells you about cloud height.
As you can clearly see, the pattern is very different between 8c and 8d. But in 8a you see that the sea surface temperature anomalies were almost identical.
To make things even more complicated, some believe there are two kinds of El Nino Modoki's and this is described here. Among other things, the referenced article provides the details on how the following breakdown was developed. Based on these authors, we have since 1950 had sixteen El Ninos broken down as follows:
Although both the researchers work for NOAA and were based in Miami Florida when they did this research, they seem to have used the Chinese System of identifying an El Nino i.e. focusing on Nino 3.0 rather than Nino 3.4. Nino 3.0 is the eastern part of Nino 3.4. This may explain the slight difference between their characterizations and that of Bob Tisdale and NOAA in that these Chinese authors do not seem to recognize 2006/2007 as any kind of El Nino. It barely met the ONI criteria of five consecutive overlapping three month periods with the ONI being 0.5 or higher and in the first period it was exactly 0.5 so it may very well have not recorded as an El Nino when Nino 3.0 was used as the criteria rather than Nino 3.4 which is a bit further west.
That does not seem to be a good explanation to me but this was "barely" an El Nino and any slight change in criteria could rule it out. Tisdale categorized it as a canonical El Nino and when I look at the precipitation situation in New Mexico and the values of the PDO Index it seems to me that this was more of a relief between two La Nina events, one of which was quite strong, rather than an El Nino so I think the characterization in the above table is probably more on target than the NOAA characterization although it is a borderline case.
But the general conclusion is that since the PDO turned negative in 1998 we may not have had a traditional or what is called technically a canonical El Nino. I have not yet matched the above categorization of Modoki I and II to precipitation patterns in the U.S. The referenced authors focused on the Western Pacific mainly China.
It tells me that we have to be very careful about how we relate to something called an El Nino since there are at least three varieties and each has a different impact on Global Weather.
Let us talk a bit more about the work of Chunzai Wang and Xin Wang. From the abstract of their article.
Here are the cyclone tracks for the three flavors of El Nino
As you can see:
A very good reference to the literature on ENSO can be found here. It is an amazing document and the discussion on Global Warming is very interesting. There is no consensus on how Global Warming has or will impact ENSO although many think it does, But they disagree on how!
All of this is very important for many reasons which technically boil down to how the overall behavior of the Pacific and Tropical Pacific are interrelated. Currently we decompose the Pacific into the Pacific north of the Equator which we describe by one index called the PDO and the Tropical Pacific which we describe by one index called the ONI. But from what I read (and I have in this article provided the links) it probably is less than fully productive to look at things the way we have been looking at things and I anticipate that more people will be looking at things differently.
Comparing El Nino to La Nina
The first two graphics, and there are many versions of these graphics but the above are very colorful, show how the Jet Stream tends to be further south during an El Nino (not this past winter). Notice the Aleutian Low in the El Nino graphic. The Blocking High in the La Nina pattern is reminiscent of summer weather but it is further off shore than a typical summer so it allows Pacific storms to enter the U.S. via the Northwest.
Now we take a look at the Walker Circulation which is where the warm water causes evaporation and convection (cloud formation) and where these clouds tend to drop their precipitation which creates downwards air movements. The colors also reveal the location of warmer than climatology and cooler than climatology Sea Surface Temperatures (SST) which are used to define the pattern. Pay special attention to the water along the Equator.
It is difficult to see the difference between the La Nina (above) and Neutral conditions (below) but you should pay attention to the more pronounced (darker - thicker arrows) convection zone in the El Nino state as compared to the Neutral state and similarly the stronger subsidence zone in the La Nina state. Subsidence tends to warm and dry air masses.
It is a lot easier to see the different between Neutral and El Nino as the pattern tends to reverse with Convection Zones converting to Subsidence (drying) Zones. This winter the Convection Zone was further west than usual and I have mentioned that almost every week.
Queensland Australia also publishes graphics on how the Walker Circulation is related to the SOI and they are very interesting.
Obviously they are mostly interested in the impact on Australia but the Walker Circulation is a worldwide process and the rightmost part of these graphics relate to North and South America.
El Nino Impacts
New NOAA Tool
I do not know when this was made available but I just noticed it which you can click on here. They say it shows the impact of ENSO but really it is set up to show the impact of El Nino with the instructions to reverse the sign for the impact of La Nina which is an approximation but is probably reasonable. The major problem I have with this is that the regression analysis did not take into account the strength of the ENSO event or the type of event i.e. for El Nino: Traditional, Modoki Type I, Modoli Type II. So it averages all El Nino events together. It is a clever graphic however as you can indicate which months you are interested in.
North Carolina has a very good State Climatologist so that is a good place to seek information on the impact of a possible El Nino. The following charts were all prepared by NOAA but I found them here so I am using them from the North Carolina Climatologist's web site.
This chart is interesting:
Notice all the red off the coast of Ecuador and Peru. The current forecast map looks a lot like this but not quite the amount of warm water off of Ecuador and Peru. So that is the difference between what is currently projected and a truly powerful El Nino.
This chart shows the impacts for December through February.
And here is the information for June through August. As you can see, El Nino (as is La Nina) is a worldwide event.
These charts do not show the impact on ocean fisheries which is another important part of the story. Wet or dry; warm or cold can have an impact related to the difference from the norm. Crops that like moisture usually thrive during wet periods but too much moisture can also be harmful and certain crops prefer it to be relatively dry. So one has to look at the impacts region by region. And of course there is the risk of flooding in some places.
Some have raised issues about the coffee crop and in the U.S. the Florida citrus harvest is often impacted by El Nino. Every area highlighted on this map is likely to be impacted either negatively or positively by an El Nino event if it occurs.
Here is another set of graphics from British Met which can be found here. It shows impacts for both El Nino and La Nina and is broken down by precipitation and by temperature. There are many ways to do this analysis and show the results.
It is very difficult for researchers to isolate internal variability (ENSO, decadal and multi-decadal ocean cycles) from the secular trend in climate due to anthropogenic forcings. That is one reason why much can be learned from observing the current impacts of El Nino, La Nina and the longer ocean cycles. To some extent, climate change resembles a continual and strengthening El Nino but there is a limit to the usefulness of that analogy since El Nino does not impact the globe in exactly the same way as anthropogenic climate change. But there are a lot of similarities.
Also every instance of a phase of a climate cycle is unique. So the above represents the typical impacts.
Focusing on the U.S.
How is El Nino likely to impact the U.S.? This first map shows the impact on temperature as compared to ENSO Neutral Conditions.
It would be colder in the south and warmer in the north but it is not a big difference. But is it enough to put the Florida citrus crop in danger? How might natural gas prices be impacted?
This map shows the impact on precipitation.
It is wetter in the West and in the Southeast.
And again these are not big differences but when you compare the El Nino data not to the mean but to La Nina conditions, it starts to be more significant.
Spring and Summer Impacts of El Nino
First let us take a look at the impact of an El Nino on Spring weather in the North Atlantic and Northern Europe Region.
"Delayed ENSO impact on spring precipitation over North/Atlantic European Region." Full article by Ivan Here Buick and Fred Scarfskin can be found here.
So what they are saying is that El Nino can lead to a wetter, cooler Spring for Northern Europe. If you read the paper you will see that there are a lot of nuances but of course the major problem is that we have not had an El Nino Winter. Nevertheless, it is reasonable to consider the increased odds, probably small, of some degree of a cooler, wetter spring in the North Atlantic/European Region.
But what if it is a Modoki and not a Traditional El Nino. This is the Abstract of an article that can be found here.
Contrasting Impacts of Two Types of ENSO on the Boreal Spring Hadley Circulation: Juan Fen and Japing Li
State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
I did not have access to the full paper but I interpret the abstract to suggest that convection zones may shift five to ten degrees of latitude north. I do not understand the full implication of this but given that there are three major circulations in each hemisphere: Hadley, Ferrell, Polar each of which nominally spans 30 degrees, a shift of the Hadley Circulation by 5 to 10 degrees north, is likely to have a significant impact which I have referred to in the past as a rotation.
You have seen this before [Author D. Windrim]
We tend to think of Planet Earth as divided into six zones: three in the Northern Hemisphere and three in the Southern Hemisphere. It all starts at the Equator where warm air rises. That air cannot travel into outer space so it moves toward one or the other of the Poles. At some point, the air cools and subsides creating what is called the Subtropical Ridge. It is another way of describing the Hadley Circulation. But the location of this Subtropical Ridge moves to some extent as part of its seasonal cycle but it is also influenced by the phase of the ENSO Cycle. Since we are in an El Nino Phase now, which will for sure last through the summer, there is a tendency for the subsidence process to occur closer to the Equator than usual. We will see how this might impact our weather this summer. It is most likely to impact the Southwest but it should also have impacts in the Southeast as well.
Here is some background information on the Subtropical Ridge.
This from a recent forecast from the Albuquerque NWS.
The point is simply that the location of certain semipermanent features such as the Eastern Pacific Subtropical High (sometimes called the North Pacific High or the RRR) and the Bermuda High (Sometimes called NASH or the Azores High) impact our weather. The Bermuda High has a 60 year cycle namely the AMO which is gradually increasing the western extension of the Bermuda High year by year at this point in its cycle. Not totally sure about the movement of the Eastern Pacific Subtropical High but you can learn a lot from this slide presentation. And this graphic tells a story.
Basically this is saying that with PDO Negative, Modokis are more likely and the Hadley Cell is stronger. But right now we have something much more like a traditional Eastern Pacific El Nino and we may have PDO Positive but for sure the Pacific Subtropical High is shifted to the East. Thus we have the Pacific High shifted or extending to the East and the Atlantic High extending to the West which puts two Highs close to each other. That is not the usual way things happen as there normally is H - L - H - L - H etc. not H - H or H - H - H. When you have adjacent clockwise systems, they do not get along well together. Thus the interesting excerpts above from the Thursday Technical Discussion released by the Albuquerque Office of the NWS. Another way of putting it is "we are not sure what will happen to the moisture from Hurricane Carlos". Also there may be a tendency for the two highs to tend to rotate around each other. I think that would most likely cause the Pacific High to move around the Bermuda High. I think I have detected what I have called "rotation" in the past. I am not talking about anything dramatic but something subtle.
We are talking about a Spring and Summer pattern that might show up frequently over the next few decades with the AMO shifting into its Neutral and then Negative Phase and be more exaggerated in El Nino years. Wouldn't it be nice if water planners understood this sort of thing?
For these first six graphics, Winter is on the Left and Spring and Summer are on the right.
First we will look at the mid-atmosphere I'm geopolitical height anomalies as this provides a good way of determining weather patterns.
There is quite a bit of change from Nov - Mar impacts to May - Sep impacts and these are anomalies relative to 1981 - 2010 climatology so it does not simply reflect the seasonal change. Less land area is impacted in the Spring and Summer than in the Winter. In general it appears to be mostly a muting of impact in the Northern Hemisphere but in the North Atlantic it is the opposite impact which we have discussed earlier as a delayed telecommuting between the Pacific and the Atlantic during a warm event in the Pacific. There appears to be an enhancement of impact in the Southern Hemisphere which is not at all strange as Spring and Summer in the Northern Hemisphere is Fall and Winter in the Southern Hemisphere and El Nino is primarily a Fall and Winter event. Australia seems to be an exception.
Next we will look at Temperature Anomalies.
It looks like the Poles see the most variation of anomalies between Winter and Spring/Summer which again is simply the reality that the seasons are reversed in the Southern Hemisphere as compared to the Northern Hemisphere. In general the impacts of El Nino are muted in the Spring and Summer in the Northern Hemisphere. But there is a tendency for the Northern Hemisphere to be slightly cooler during an El Nino Spring and Summer. Although we will look at the U.S. in more detail you can see the slight impact on the U.S. here. I will be coming back to that later.
Next we will look at precipitation.
And again the impacts are muted in the Spring and Summer except along the Equator. I was surprised by the very low level of impact in the Nov - Mar graphic on the left for the U.S. More on that later.
Focus on U.S. Impacts
Now we will zero in on the U.S. and consider impacts with higher resolution graphics.
The major impact for CONUS appears to be somewhat lower 500m geopolitical heights in the Southwest. On the other hand British Columbia seems to have the opposite occur. And there is a tendency towards lower pressure in the North Atlantic which we discussed earlier in this week's report.
Now we will look at temperature.
The major impact appears to be in the North Central states which might be a decree cooler in the Spring and Summer during El Nino Conditions. There appears to be a rather small area in Southern Nevada and Southern California that might be one degree warmer. I was perplexed at first when I noticed that the graphic on the right does not appear to agree with the worldwide graphic presented earlier. But then I realized that the earlier graphic was based on anomalies relative to 1981 - 2010 and this graphic uses 1971 - 2000 as the base climatology. This convinces me that the impacts of the Pacific (PDO) and Atlantic (AMO) may in Spring and Summer overwhelm the impacts of El Nino.
Now let us take a look at precipitation.
This is the most interesting of the graphics, a bit wetter in the Center of CONUS and quite a bit drier on parts of the East Coast. But none of this shows up in the earlier worldwide graphic. Again it seems to me that the base climatology which is different in the worldwide graphics (all of this information comes from the same website) overwhelms the impact of El Nino especially in Spring and Summer. An increase of five inches of precipitation in a small area in the Mid-west and a decrease of five inches of precipitation in coastal Alabama may seem like a large impact but even if valid it applies to two to four climate divisions i.e. a very small area. Most of the impacts shown for the center of the U.S. in this graphic are of one inch magnitude wetter or two inches of magnitude drier and summer especially tends to be wet in that part of the U.S.. So I am not sure that these anomalies are meaningful. This of course raises the question of why NOAA thought it was useful to even raise the question of whether this warm event might ultimately be declared an El Nino when the impacts on Spring and Summer are minimal at best.
El Nino versus La Nina in the Spring and Summer
Now let us shift our approach and compare El Nino Spring and Summer Impacts to La Nina Spring and Summer Impacts. These are likely to be larger as we are comparing what should be two opposite impacts in many cases. In these two graphics, El Nino is on the left and La Nina is on the right.
First we can look at temperature.
At first glance there are no surprises here. With El Nino the West is a bit cooler and with La Nina the Plains States and Great Lakes extending into the Northeast is a bit warmer. The information on El Nino should be consistent with what was shown earlier and is consistent with the worldwide graphic which uses the same base climatology.
Now we look at precipitation.
And here surprisingly we see little impact of El Nino but La Nina is clearly slightly drier for much of the Eastern part of CONUS. That was a little bit of a surprise but suggests the delayed impact of La Nina in the following season further east similar to how El Nino might telecom impacts further east on a delayed basis as described in one of the papers I reviewed earlier in this report.
You can find some interesting graphics here that differentiate between weak, moderate and strong El Nino. It also has separated out Spring impacts for Spring and Summer combined as I have done above.It is a private website so I can not just lift their graphics so I have provided you with a link to Jan Null's website which is called Golden Gate Weather Services.
General Conclusion: El Nino is not a factor in the U.S. in the Spring or Summer and NOAA and some in the Media have wasted a lot of people's time.
California Niño/Niña. It seems that Baja California has its own cycle of changes in the upwelling of cold water and that this may be somewhat independent of the ENSO process but be instead specific to Baja California and Southern California. More information on this can be found here.
The map to the left shows the geographic area we are talking about and the chart on the right shows: (a) Lead-lag correlation coefficients between the July-September California Niño/Niña indices and the 3-month-running mean California Niño/Niña (CA, grey filled bar), along-shore surface wind (ASW, dark open bar) and upwelling (UWI, blue line) indices from 1982-2011. The ASW is positive equatorward, and UWI positive upward.
This is a difficult graphic to interpret but basically it is showing that July to September conditions in the summer impacts wind and upwelling into the following winter and this may not be connected to the ENSO Cycle but is a separate (intrinsic) phenomenon.
A couple of thoughts about this research:
A. It is interesting how the Japanese found this pattern rather than some professor at a California University. Does this tell us anything about the lack of focus by the U.S. on U.S. climate other than projects funded under the rubric of Climate Change?
B. There more than likely are other similar micro climates like this. Micro is relative as this pattern may impact a fairly large area.
Comparing Current El Nino to 1997/1998 El Nino
First a graphic provided by Andrew Church of the Aluquerque NWS Office.
Let us discuss perhaps the most famous El Nino ever (although the 1982/1983 El Nino is famous also). I have been able to include the links to the NOAA graphics in the following NOAA Discussion (so you can click on the Figures indicated in the article) but not the links that move you between sections of the article as GEI does not support those commands and they complicate reading the article. You can read the article in the original by going to the El Nino of 1997/1998 . The purpose of this discussion is to compare and contrast the current El Nino with the World Champion 1997/1998 El Nino. The text in the report is the complete article from NOAA. I have selectively added some of their graphics into the article here so you do not have to click on those to see them. Also, I have added some graphics from the current El Nino for comparison and some of my comments as [Editor's Notes].
As mentioned above, my analysis is still a work in progress. I may do some additional work on it during the week and present a more complete analysis in my August 17 Weather and Climate Report or at a later time. Let's face it. Every El Nino is different so it is not easy to compare one to another. But the comparison may be informative and helpful to those who can benefit from additional insight into how this El Nino may evolve. And it is important to remember that for CONUS, the major impacts are likely during Fall so the data I am presenting is prior to the full impact of this El Nino, not a retrospective. Not everyone will want to wade through this detailed and highly technical analysis so they can scroll down to the section on current weather conditions and forecasts. .
From what I see so far, It suggests that this El Nino is not going to match the 1997/1998 El Nino but it is closer to it than one might think. I suspect the Faux El Nino of 2014/2015 discharged some of the energy in the ENSO battery or we might be having a record matching or beating El Nino right now. Also, and not much discussed, this El Nino is arriving early and thus may have lesser impacts on the Northern Hemisphere. One thing I have learned from attempting this comparison is that El Nino is very much about the Southern Hemisphere and not much information is presented on that in the NOAA Weekly ENSO Update.
From the CPC.NCEP.NOAA Report on this subject, with the link provided above, Very strong 1997-98 Pacific warm episode (El Niño)
The global climate during 1997 was affected by one of the strongest Pacific warm episodes on record. These warm episode conditions developed rapidly in March, with strong ENSO conditions persisting from May through the end of the year (and subsequently well into 1998) (Figs. 20, 21 ). During this episode the abnormally warm SSTs which covered the eastern half of the equatorial Pacific (Fig. 21a) were comparable in magnitude and areal extent to the famed 1982/83 El Niño (Fig. 20a). These 1997 warm episode conditions were accompanied by a strong negative phase of the Southern Oscillation, with the equatorial Southern Oscillation Index (SOI) also comparable in magnitude to that observed during 1982/83 (Fig. 20b). Also evident since April was a markedly reduced strength of the low-level (850-hPa) equatorial easterly winds across the eastern tropical Pacific (Fig. 21c). At times these anomalies indicated a complete disappearance of the easterlies across the entire eastern Pacific, along with a complete collapse of the normal equatorial Walker circulation. These anomalies were also comparable to those observed during the 1982/83 El Niño (Fig. 20c).
The above conditions were associated with a dramatic alteration of the global pattern of tropical rainfall and deep tropical convection, as indicated by above-normal rainfall across the eastern half of the tropical Pacific and by significantly below-normal convection across Indonesia and the western equatorial Pacific (Fig. 22). The combined zonal extent of these rainfall anomalies covered a distance more than one-half the circumference of the earth.
Selected impacts associated with these warm episode conditions included 1) excessive rainfall across the eastern half of the tropical Pacific, 2) significantly below-normal rainfall and drought across Indonesia and the western tropical Pacific, 3) below-normal hurricane activity over the North Atlantic during August-October, with a simultaneously expanded region of conditions favorable for tropical cyclone formation over the eastern subtropical North Pacific 4) excessive rainfall and flooding in equatorial eastern Africa during October-December 5) a dramatic eastward extension of the South Pacific jet stream to well east of the date line during June-December which resulted in enhanced storminess across southeastern South America and central Chile and abnormally dry conditions across the Amazon Basin, central America, the Caribbean Sea and the subtropical North Atlantic throughout the period.
2. Evolution of the 1997 El Nino
The year began with a continuation of weak cold episode conditions in the tropical Pacific during December 1996-February 1997 (DJF 1996/97). These conditions included a well-defined tongue of abnormally cold SSTs extending across the eastern tropical Pacific (Fig. 23b), with equatorial SSTs greater than 28°C confined to the area west of the date line (Fig. 23a). SSTs were slightly below normal in the Niño 1+2 region (Fig. 24a), the Niño 3 region (Fig. 24b) and the Niño 3.4 region (Fig. 24c), and substantially below the 28°C threshold for convection (Gadgil et al. 1984) in all three regions
[Editors Note: I have added a graphic which has two sets of information. The left-hand figure is the long-run history of the Nino 3.4 reading which in the U.S. is the major way of tracking the phases of ENSO i.e. El Nino versus Neutral versus La Nina. It goes back to 1950 so you can easily see the 1997/1998 El Nino there followed by a long La Nina and then a series of weak El Nino's. It is easy to follow that graphic and you can see how rapid the buildup was in the Nino 3.4 reading which is often referred to as the ONI the Ocean Nino Index. On the right is more recent information but not just for the ONI which is the second row down but for four Nino Indices representing different areas along the Tropical Pacific and they go from west to east with the Nino 1 + 2 being a little south of the Equator to cover Equador and Peru. You can see that it has not been as dramatic a rise although one always has to be careful when reading a graph to be aware of the way the X and Y axis are structured. There was the Faux El Nino in the winter of 2014/2015 which was a false start and probably drained some of the energy from this warm event which otherwise would probably be even stronger and rival the 1997/1998 El Nino. You can see that until recently it has been mostly a Central Pacific warm event (Nino 4) which some call a Modoki. We clearly are in an El Nino now but the Nino 1+2 area SST anomalies appear to have peaked and leveled off. There is a lot of information in this combined graphic. It does not auto-update but NOAA updates this information weekly in their ENSO Report so it is avaiable.]
The colder-than-normal conditions were accompanied by a strongly sloping equatorial oceanic thermocline (Fig. 25a), with increased thermocline depths across the western Pacific and reduced depths over the extreme eastern Pacific [The center of the thermocline is approximated by the 20°C isotherm]. These variations in thermocline depth were accompanied by abnormally warm ocean temperatures in the western and central tropical Pacific between 50-200 m depth and by abnormally cold water in the eastern tropical Pacific between the surface and 50-100 m depth. During this period, the atmosphere featured 1) a positive phase of the Southern Oscillation, with below-normal sea level pressure (SLP) across the western tropical Pacific (Fig. 21b), 2) a broad area of slightly enhanced low-level easterlies across the central tropical Pacific (Figs. 21c, 26a ), 3) enhanced tropical convection over Indonesia and the western tropical Pacific [indicated by negative values of anomalous Outgoing Longwave Radiation (OLR)] and suppressed convection in the vicinity of the date line (Fig. 26a), and 4) westerly wind anomalies at upper levels across the eastern tropical Pacific (Fig. 27a). Collectively, these conditions reflected an enhanced equatorial Walker circulation and a continued coupling between the positive phase of the Southern Oscillation and below-normal SSTs across the eastern tropical Pacific.
In contrast, March and April featured an extremely rapid transition to one of the strongest warm episodes of the century. SSTs increased nearly 1.5°C over the normal annual cycle in the Niño 1+2 region during March (Fig. 24a), and nearly 1.0°-1.5°C over the annual cycle in the Niño 3, Niño 3.4 and Niño 4 regions. In the Niño 4 region this increase occurred during a two-week period and was greater than the entire annual cycle of SST for that region. A second period of very rapid SST increases in the east-central Pacific then occurred during April, as SSTs in both the Niño 3 and Niño 3.4 regions climbed an additional 1°C over that expected from the normal annual cycle. Thus, by mid-April SSTs exceeded 28°C across the central and east-central equatorial Pacific (Figs. 24b-d ), with values averaging 1°-3°C above normal in all four Niño regions. Area-averaged SSTs in the Niño 3, Niño 3.4 and Niño 4 regions then remained nearly constant at values greater than 28°C throughout the remainder of the year. This warming reflected a nearly complete elimination of the annual cycle in SSTs across most of the equatorial Pacific, which is normally characterized by a peak in temperatures during March-April and a minimum during September-October.
For the MAM season as a whole, mean SSTs greater than 29°C extended to east of the date line, and values greater than 28°C extended to approximately 160°W (Fig. 23c). These temperatures averaged 0.5°-2.0°C above normal across the central and east-central tropical Pacific (Fig. 23d). This warming was accompanied by increased depths of the oceanic thermocline everywhere east of the date line (Fig. 25b), and by a flattening of the thermocline across the region. In the eastern tropical Pacific, this suppressed thermocline reflected substantially reduced oceanic upwelling in association with a weakening of the low-level equatorial easterly winds (westerly wind anomalies) (Fig. 26b ). These conditions were accompanied by suppressed convection throughout Indonesia and enhanced convection in the vicinity of the date line, which is opposite to the pattern observed the previous season.
Editor's Note: Although labeled Outgoing Longwave Radiation Anomalies the OLR (description from NOAA: Negative (Positive) OLR are indicative of enhanced (suppressed) convection and hence more (less) cloud coverage typical of El Niño (La Niña) episodes. More (Less) convective activity in the central and eastern equatorial Pacific implies higher (lower), colder (warmer) cloud tops, which emit much less (more) infrared radiation into space) is a surrogate for precipitation with blue being wet and the red shades being dry. So in MAM we had the suppressed convection in the Western Pacific and increased precipitation near the Date Line. But we have not yet had the 1997/1998 shift in precipitation to the Eastern Pacific. In fact there has not been much chance since May. You can also look back on this Hovmoeller and see the Faux El Nino of 2014/2015 and see why I never concluded that it was real].
It may be useful to compare the current OLR Anomalies with the 1997/1998 Super El Nino.
It is now August and this El Nino is a bit early but the OLR pattern has not shifted to the East as in did with the 1997/1998 El Nino. It still could happen, but so far it has not. There has been almost no impact.
During JJA, SSTs remained very warm throughout the entire eastern half of the tropical Pacific, with the 29°C isotherm expanding eastward to approximately 150°W, and the 28°C isotherm extending eastward to approximately 125°W (Fig. 23e ). These extremely warm waters are highly abnormal for that time of year (Fig. 23f), a period normally characterized by a marked decrease in SSTs across the eastern tropical Pacific. As a result, SST anomalies increased substantially throughout the region, and exceeded 3°- 4°C between 130°W and the west coast of South America (Fig. 23f). [Editor's Note we are currently running about 2.6C and I do not think it will increase but it might. So this El Nino is just under the 1997/1998 El Nino on that metric.]. This increase in anomalies was accompanied by a further flattening of the oceanic thermocline across the eastern Pacific (Fig. 25c), as the 20°C isotherm dropped to more than 100 m depth and ocean temperatures increased to more than 7°C above normal between 50-125 m depth. [Editor's Note: It this case it has been 6C but mostly 5C. However one has to keep in mind the base keeps on being adjusted by NOAA due to a trend that may be Global Warming or may be the PDO but the main point is that anomalies and absolute values are not the same thing. So the subsurface water temperature is slightly higher than the anomaly indicates.]
[Editor's Note: I incorporated Figure 25 from the NOAA report directly in the discussion because of its importance so you do not need to call up that link.]
[Editor's note: for comparison purposes this is the current subsurface Thermocline situation
[Editor's Note: One of the things I notice is that our current conditions correspond to the Sep-Oct-Nov conditions in 1997 with just a slight difference in intensity.
It is difficult to read the NOAA graphic for 1997 but it looks like an anomaly of 7C and the most extreme we have had is 6C over a smaller area of the subsurface. At this time of the year in 1997 the warm anomaly covered a much larger extent of the Equator. There was no sign of an Upwelling Wave to signal the end of the Kelvin Wave Activity. I have sensed that we have been in the final stages of this El Nino and this analysis makes me more confident that what I have sensed is indeed correct. At one point it seemed that his was an El Nino that arrived late but that was because we were considering the Faux El Nino of 2014 as a warm event that was slow in getting started. Now I am thinking what we have is a warm event that is peaking early. I am also thinking that the weather services may not be sufficiently taking that into account in their long-term forecasts]
The JJA period also featured an increasingly negative phase of the Southern Oscillation, and a further decrease in the strength of the 850-hPa easterly winds (3-6 m s-1 below normal) across most of the central and eastern tropical Pacific (Fig. 26c ). These conditions were accompanied by increased tropical convection (Fig. 26c) and rainfall across the entire eastern half of the Pacific, and by decreased rainfall across the western tropical Pacific and Indonesia. These changes in tropical convection reflected 1) a pronounced eastward extension of the primary area of tropical convection to well east of the date line, and at times an actual shift of the main region of tropical convection to the eastern half of the tropical Pacific (not shown), and 2) a strengthening and equatorward shift of the intertropical convergence zone (ITCZ) in the Northern Hemisphere (not shown). [Editor's Note: I thought I would show what things look like this year compared with the very powerful 1996-1997-1998 El Nino. Notice the SOI went very negative early in 1997. Also notice it went positive the following Spring.
And here is the current reporting of the SOI
The 1997 El Nino came on suddenly. This one has had a gradual build up re the increasingly negative SOI ] Also observed during JJA was the development of an anomalous upper-level anticyclonic circulation in the Southern Hemisphere subtropics between the date line and 90°W (Fig. 27c). This feature is a recurring aspect of the winter hemisphere circulation during strong warm episodes (Arkin 1982), and reflects several important changes in the flow occurring in the Tropics, the subtropics and the extratropics. In the Tropics, the equatorward flank of the circulation anomaly reflects anomalous upper-level easterly flow across the eastern Pacific, and thus comprises important structural elements of the much weaker-than-normal equatorial Walker circulation observed during the period. In the subtropics, above-normal heights (not shown) accompanying the anticyclonic circulation anomaly reflect an eastward extension of the mean subtropical ridge to well east of the date line, in response to the increase in tropical convection and deep tropospheric heating across the eastern tropical Pacific. In the extratropics, the anomalous anticyclonic circulation is an integral component of the coupling process between changes in tropical convection and changes in the wintertime jet stream across the South Pacific. The Southern Hemisphere circulation was also characterized by recurring high-latitude blocking over the high latitudes of the eastern South Pacific, a feature typical of strong warm episode conditions (Karoly, 1989).Strong warm episode conditions continued during SON (Figs. 23g, h), with SSTs greater than 28°C extending eastward from Indonesia to 125°W and greater than 29°C extending eastward to approximately 140°W (Fig. 23g). The normal cold-tongue that typically occupies the eastern half of the tropical Pacific at this time of the year was notably absent, consistent with the collapse of the normal annual cycle in SSTs throughout the region (Figs. 24b, c). A nearly isothermal temperature structure was also observed from the surface to 150 m depth, with ocean temperatures exceeding 9°C above normal at 50-150 m depth in the eastern Pacific (Fig. 25d).
Also during SON, El Niño-related enhanced rainfall and heavy tropical convection developed across equatorial eastern Africa. This rainfall was associated with low-level easterly wind anomalies across the tropical Indian Ocean (Fig. 26d), and with a continuation of extremely suppressed convection throughout Indonesia. Also observed was a continuation of enhanced upper-level westerlies and an extended jet stream across the subtropical South Pacific (Fig. 27d), resulting in continued heavy precipitation across Chile and southeastern South America. Elsewhere, above-normal rainfall and increased storminess developed across the Gulf Coast of the United States (Fig. 22), in association with enhanced upper-level westerlies across the southern tier of the country.
3. Equatorial Walker Circulation
Over the equatorial Pacific the divergent component of the atmospheric circulation is intimately related to the distribution of tropical convection, which in turn is an integral part of the still larger Southern Oscillation (Bjerknes 1969). This divergent circulation is often partitioned into its zonal and meridional components, respectively called the equatorial Walker circulation and the tropical Hadley circulation. The equatorial Walker circulation is characterized by ascending motion over Indonesia and the western tropical Pacific, and descending motion over the east-central equatorial Pacific, with upper-level westerly (low-level easterly) flow completing the "direct" circulation cell. Following Halpert and Bell (1997), we illustrate the equatorial Walker circulation using pressure-longitude plots of the vector field whose horizontal component is the divergent zonal wind and whose vertical component is the scaled pressure vertical velocity. The pressure vertical velocity was subjectively scaled to give a sense of the relative vertical motion in the equatorial plane. The seasonal mean equatorial Walker circulation and anomalies during 1997, along with the accompanying seasonal relative humidity anomalies, are shown in Fig. 28.
During DJF 1996/97, a well-defined equatorial Walker circulation was present (Fig. 28a), with ascending motion over the western tropical Pacific, descending motion over the eastern Pacific and a circulation center near 170°W. These conditions reflected a slight strengthening and an overall westward shift of the circulation center compared to normal (Fig. 28b), consistent with weak cold episode conditions and a positive phase of the Southern Oscillation. These conditions dissipated rapidly during MAM 1997, as a near-normal strength and location of the Walker circulation prevailed (Figs. 28c, d).
By JJA 1997, ascending motion and deep tropical convection encompassed the tropical Pacific between 140°E and 120°W (Fig. 28e ), while no well-defined pattern of vertical motion was evident over Indonesia. This anomalous vertical motion field (Fig. 28f) reflected a nearly complete disappearance of the equatorial Walker circulation. The pattern was also accompanied by enhanced relative humidity everywhere east of the date line, and by reduced relative humidity across the western tropical Pacific and Indonesia. These conditions strengthened during SON 1997, with the equatorial Walker circulation again nearly absent (Figs. 28g, h).
4. South Pacific jet stream during July-September 1997
In both the Northern and Southern Hemisphere, the extratropical wintertime jet stream over the western and central Pacific is intimately related to the distribution of tropical convection across Indonesia and the tropical Pacific. Thus, the interannual variability of these jet streams is strongly influenced by the ENSO. During strong El Niño conditions the wintertime jet stream extends eastward to well east of the date line, and over the eastern Pacific is shifted well equatorward from normal. These changes in the jet stream reflect a deep baroclinic jet structure often extending across the entire Pacific Basin, along with a pronounced eastward shift of the normal jet exit region to well east of the date line. These conditions then contribute to enhanced storminess and above-normal precipitation at lower latitudes of both North and South America.
During 1997, the South Pacific jet stream was particularly impacted during July-September by the ongoing strong El Niño conditions, while the primary impacts on the North Pacific jet stream did not occur until early 1998. Thus, this analysis focuses on the wintertime South Pacific jet stream, which extended across the entire South Pacific and brought enhanced storminess and above-normal precipitation throughout Chile and southeastern South America [Editor's Note" This longer current animation shows how the Jet Stream is crossing the Pacific. Perhaps the followin graphic which includes a discussion of how the Polar Jet Stream is usually impacted by ENZO will be helpful]
[Editors's Note: I have not seen this happening. In general the Jet Stream has been further north rather than further south. This may change in the coming months.]
The core of the South Pacific jet stream (approximated by wind speeds greater than 50 m s-1) during July-September is typically located between 22.5°-32.5°S and extends eastward from eastern Australia to approximately 150°W (Fig. 29a ). The jet entrance region is normally located over eastern Australia, and is characterized by a local maximum in along-stream increases in geostrophic wind speed. Additional characteristics of the entrance region include confluent geostrophic flow at upper levels and a strong poleward component of the horizontal ageostrophic flow directed toward lower geopotential height. This ageostrophic flow is one component of the thermodynamically direct, transverse ageostrophic circulation typical of any midlatitude jet entrance region (Palmen and Newton 1969, sections 1.5 and 8.3; Hoskins et al. 1978, Keyser and Shapiro 1986), and produces the required westerly momentum and kinetic energy increases that air parcels experience as they approach the jet core.
Farther downstream, the jet exit region is normally found between the date line and approximately 125°W, and is characterized by a local maximum in along-stream decreases in geostrophic wind speed. Characteristic features of this exit region include diffluent geostrophic flow at upper levels and a strong equatorward component of the ageostrophic flow directed toward higher geopotential height. This ageostrophic flow is one component of the required thermodynamically indirect, transverse ageostrophic circulation typical of any midlatitude jet exit region, and produces the required westerly momentum and kinetic energy decreases that air parcels experience as they exit the jet.
The July-September 1997 period featured an eastward extension of the jet stream across the entire South Pacific (Fig. 29b), and an extension of the jet core to 105°W (nearly 45° east of normal). This extension was accompanied by a pronounced eastward shift in the regions of along-stream decreases in geostrophic wind speed and strong diffluent geostrophic flow, and by a nearly complete elimination of these features in the vicinity of the climatological mean jet exit region. Collectively, these conditions reflected an eastward shift in the location of the jet exit region to between 130°-90°W. This dramatic structural change in the jet stream was accompanied by a dynamically consistent eastward shift in the primary region of equatorward-directed ageostrophic flow at upper levels to the observed jet exit region, indicating a corresponding shift in the entire thermodynamically indirect, transverse ageostrophic circulation that characterizes the jet exit region.
This jet extension and eastward shift of the jet exit region were intimately related to an eastward extension of the subtropical ridge to well east of the date line, which is identified by a well-defined anticyclonic circulation anomaly across the entire eastern subtropical South Pacific during JJA and SON (Figs. 27c, d). Additional aspects of this link between the two features are revealed by examining their common attributes. One common feature is the region of enhanced westerlies over the eastern South Pacific, which comprises both the poleward flank of the anticyclonic circulation anomaly and the extended South Pacific jet stream (compare Figs. 27c, and 29b, c). Two additional common features are the poleward flow and equatorward flow along the western and eastern flanks of the anticyclonic anomaly, respectively, which contain important dynamical information regarding links between the anomalous subtropical ridge and changes in the jet entrance and exit regions.
[Editor's Note: Here is a better look at the current Western Pacific.]
[Editor's Note: But this is the North Pacific not the South Pacific. Below is the South Pacific but I am not sufficiently familiar with that graphic to fit it into the discussion but it is amusing to see low pressure areas spinning clockwise. But I was expecting to see a giant anti-cyclone and I do not see it. I do see westerlies. I have more work to do!]
The anomalous poleward flow comprises several important structural changes occurring in the exit region of the climatological mean Pacific jet. First, it contributes to anomalous geostrophic confluence throughout the region (Fig. 29c), which also coincides with the entrance region of the anomalous westerly wind maximum. Second, it comprises a dynamically consistent pattern of anomalous ageostrophic flow at upper-levels, directed toward lower geopotential heights at an angle nearly orthogonal to the jet axis. This ageostrophic flow reflects an anomalous thermodynamically direct, transverse ageostrophic circulation, and results in abnormally strong Lagrangian increases in kinetic energy throughout the region (Fig. 30a). In this particular case, both the rotational (Fig. 30b) and divergent (Fig. 30c) components of the ageostrophic flow contributed strongly to these kinetic energy tendencies. Collectively, these anomalies are consistent with an almost complete elimination of the normal jet exit region in the vicinity of the date line, and with a reduced strength of its attendant transverse ageostrophic circulation.
A similar examination indicates that the equatorward flow along the eastern flank of the anticyclonic circulation anomaly comprises important structural and dynamical features of the observed jet exit region. For example, this equatorward flow contributes to geostrophic diffluence in the observed jet exit region (Fig. 30c), an area which also coincides with the exit region of the anomalous westerly wind maximum. The equatorward flow also comprises a coherent pattern of ageostrophic flow directed toward higher geopotential heights at upper levels, at an angle nearly orthogonal to the jet axis. This ageostrophic component of the flow reflects the well-defined thermodynamically indirect, transverse ageostrophic circulation previously noted in the jet exit region, and results in Lagrangian decreases in kinetic energy throughout the area (Fig. 30a). In this case, the rotational component of the ageostrophic flow contributes more to these kinetic energy tendencies (Fig. 30b) than does the divergent component (Fig. 30c).
Thus, in this case the anomalous poleward and equatorward flow found respectively along the western and eastern flanks of the anticyclonic circulation anomaly are strongly linked to jet dynamical processes through El Niño-related changes in the subtropical ridge. These flow features also highlight the jet-like character of the anomalous westerly wind maximum found along the poleward flank of the anticyclonic circulation anomaly.
Past History of ENSO Events.
Let's look at the history. It may not be the best index but the Oceanic Nino Index or ONI is the one most used and can be found here. Red is a warm sea surface anomaly along the Equator in the Pacific in an area called Nino 3.4. Blue is a cool anomaly.
Recently Updated but my below analysis is based on the above table which is what I had at the time. This is more uptodate.
Thus El Nino, El Nino Modoki and La Nina as well as ENSO Neutral should be considered normal events and part of the rhythm of Nature and not sensationalized. And yet each phase has positive and negative impacts on different parts of the World or at least half of the World and probably much more than half.
Analysis of the Above ONI Data
Now let us analyze that data. You can follow what I have done as all I have done to get started is look in the above table for five or more consecutive three-month periods where the ONI was 0.5 or greater (El Nino) or -0.5 or less (La Nina) as that is the NOAA definition of an El Nino or La Nina but in theory the synchronization with the Atmosphere must also be present but for now let's ignore that as I have no way of easily going back to see how the atmosphere and ocean were relating.
I need to review this table a couple of times before I draw too many conclusions as I may have made some errors mostly in terms of categorizing the period of time during an ENSO event as being PDO and AMO positive or negative. Those indices vary by month so it is tough to determine what the condition was for the duration of the ENSO event. In the left hand column for El Nino's I have designated them as Traditional (T) or Modoki (M). The literature on which ENSO events were a Modoki is not always clear and since it is a Japanese concept, the ENSO events which were considered by JAMSTEC to have been an El Nino are not 100% the same as those designated by NOAA. But the correlation is pretty close.
By my count (and over the next week I will check my work) we have had 22 El Nino Events and 14 La Nina Events since 1950 so that is about 36 events in 65 years. So ENSO events are not rare. About 15 of those El Nino events were Modokis which could be argued are closer to ENSO Neutral than being an El Nino so if one eliminates some percentage of the El Nino Modokis, you end up with perhaps about an equal number of El Ninos and La Ninas. I will look at the ocean conditions associated with these ENSO events during the week. Some believe the ocean conditions, especially the PDO, impact the ratio of El Ninos to La Ninas. Others believe that Global Warming may be the cause of so many Modokis. The three most powerful El Ninos were all traditional El Ninos as is the current one. But the current El Nino is quite different from any of the prior three champions so drawing conclusions about it is not straightforward.
Here is a list of ENSO events since 1950. The same information is shown earlier but in a different format. Notice the ONI values for a La Nina never exceed absolute value of 2.0. These divisions are arbitrary but convenient. It is not clear that impacts are proportional to the ONI. But it provides a general idea of how many El Ninos and La Ninas there have been and how they measured up on the ONI scale. Most ENSO events are weak and have little impact on weather. There have been 21 ENSO events since 1950 which have been other than weak. That is about a third of the 65 year period. Given that the most recent El Nino was a "wimp" it seems that we have not had a strong ENSO event yet this Century.
So far I have not been able to find a comparable El Nino to compare with our current El Nino which makes it very difficult to really have an opinion as to how this is going to play out.
La Nina Impacts
Focusing on India and Australia.
Both India and Australia are bordered by the Indian Ocean but Australia is bordered by both the Indian and Pacific Oceans. How does his impact their climate?
Think about currents
ndian Ocean Dipole (IOD)
The IOD is defined as the difference between SST anomaly in a western area (60E-80E,10S-10N) and an eastern area (90E-110E,10S-0S).
The Australian Bureau of Meteorology has their own proprietary Model (POAMA) for forecasting the IOD.
It comes with only a very short discussion which can be found here.
To what extent are the ENSO and IOD related? That is discussed here.
And how does the IOD impact Australia? This is discussed here.
And there are variations of IOD. So if one wants to really delve into the subject you could read this article.
Thus it is easy to remember how to interpret the IOD. "+" means warm to the west and "-" means warm to the east.
Here is a discussion of how El Nino Modoli impacts the IOD.
Different impacts of various El Nino events on the Indian Ocean Dipole
Xin Wang and Chunzai Wang
Focusing on China and Japan.
This discussion of how the impacts of El Nino and El Nino Modoki impact China and Japan can be found here.
Much information on a variety of such cycles can be found here.
Attempting to Extrapolate to the Impact of Ocean Cycles Worldwide - a First Attempt at Putting it all Together.
This table is a first attempt at putting it all together. It is just that: a first attempt. Anyone with additional information please provide it to me by sending it to the GEI Publishers.
Attempting to put this into a two-dimensional matrix may not have been a good idea as there are not only impacts among the ocean cycles shown across the top of this matrix but also interactions with the air pressure cycles (which themselves may be related to Ocean Cycles.) So look at this matrix as just a first attempt at showing the interactions. I will be refining it. There may be conflicts not only in the literature but also due to the interaction of so many different forcings including climate change so again this is just a starting point to think about how these different cycles impact our climate. NA perhaps should have been NS as meaning not significant. All the cycles impact everything but some have more impact than others and that is what I am attempting to show.
Atlantic Multidecadal Oscillation (AMO) Index can be found here.
It is useful to understand the Atlantic Meridional Overturning Circulation (AMOC) which if you ignore the wind component is called the Thermohaline Circulation since changes in salinity as the water moves north plays a big role. You can read about that here.
Another way at looking at things is to think about the models of variablity in the North Atlantic. This paper by Iris Grossmann and Philip J. Klotzbach can be found here.
This is a good time to discuss the Atlantic Multidecadal Oscillation or AMO. It has a big impact on CONUS summer weather especially precipitation and we will be discussing this more in the weeks ahead. This graphic is from the paper Variations in North American Summer Precipitation Driven by the Atlantic Multidecadal Oscillation QI HU,SONG FENG, AND ROBERT J. OGLESBY. Here is the link. We will be discussing this and related papers a lot more in the coming weeks.
Pacific Decadal Index (PDO) can be found here. The original research paper describing the PDO (even before it was named) can be found here. This is an index that covers both the north and south Pacific and is called the Interdecadal Pacific Oscillation Index.
At this point it might be useful to discuss the PDO. The below shows the different pattern of where the surface water is warm and where it is cool in the Pacific during two most discussed phase of the PDO. The graphic on the left is PDO+ and notice how well it conforms to where the models say we will be in the second quarter of 2015. Actually that is about where we are today. It is very different from conditions since mid 1998.
The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. And here is a later version but I do not have a link that shows it in color but I believe the maps have not changed from the earlier version.
The key maps are shown below:
Drought frequency (in percent of years) for positive and negative regimes of the PDO and AMO. (A) Positive PDO, negative AMO. (B) Negative PDO, negative AMO. (C) Positive PDO, positive AMO. (D) Negative PDO, positive AMO.
As of the time that I have last updated this document, September 29, 2014, the PDO Index has become positive but slowly declining back towards normal and the AMO Index flirted with going negative but is currently again positive i.e. the situation is currently PDO + (warm)/ AMO + (warm) or consistent with the C regime in the above McCabe et al graphic. Clearly this is a situation that requires close monitoring. The current values of the PDO and AMO may not be nearly as significant as values that generally remain the same sign for a lengthy period of time.
Here is another approach that is worldwide in nature but only focuses on the Pacific Ocean.
Currently an issue of great importance is whether or not the pattern of warmer areas versus colder areas in the Pacific has changed. Such changes are often referred to as a Pacific Climate Shift. There is some discussion that we may be either in a Pacific Climate Shift now or that one may be imminent.
Recently I referenced this article and this article which address this subject but did not discuss them. I thought I would need to discuss both but it turns out that the first link covers both the 1977 - 1998 Positive Phase of the PDO and the 1947 - 1976 Negative Phase of the PDO. So I will focus on just that first paper: "Tropical Pacific Forcing of a 1998–1999 Climate Shift: Observational Analysis and Climate Model Results for the Boreal Spring Season Bradfield Lyon, Anthony G. Barnston, David G. DeWitt". What is very unusual is that these authors are addressing the Northern Hemisphere Spring/Southern Hemisphere Fall while most climate researchers focus on winter or summer. So this is unusual and thus to me especially interesting.
One complication in presenting this material is that I am most comfortable characterizing the condition of the Pacific using a particular index the Pacific Decadal Oscillation or PDO. The PDO refers to the Northern Hemisphere but there is a related index called the Interdecadal Pacific Oscillation (IPO) that covers both Hemispheres. As I discuss the Lyon et al. paper you will see that the authors do not rely on any of these indices to aggregate data for their graphics since basically their methodology recreates them. I am using the terms PDO and IPO in my discussion as do the authors in their article to provide a frame of reference that fits with other information I have presented.
Most of the findings in that paper that I want to discuss show up in the below graphic. Unfortunately, unless you have a color printer you need to view this on the screen. It is a very simple graphic really. The authors have removed the impact of Global Warming and the ENSO cycle. So they really are attempting to capture the impact on precipitation of the changes from one Pacific Ocean configuration to another. For purposes of relating the discussion to the U.S. I have taken the liberty in my comments to refer to the periods of time they are comparing as being periods which are considered to have been PDO Positive or PDO Negative. For certain readers a reference to the IPO would be perhaps more recognizable but the PDO and IPO are highly correlated. In the graphic the authors just display their data in terms of periods of time but those periods can be described by the PDO index and (as well as the IPO index) I have done that.
With respect to the below graphic,
Figure 4a compares precipitation since the PDO went Negative to the period of time (1977 - 1998) when it was Positive.
Figure 4b compares 1977-1998 with 1947-1976 the prior negative configuration of the Pacific.
So in both cases the goal is to compare a period of PDO positive with a period of PDO negative and since it is looking at the entire world, the IPO is used not the PDO. The IPO covers the entire Pacific not just the Northern Hemisphere. Again, the authors discuss the IPO but do not use it as part of their methodology as their methodology is the methodology used to define the IPO.
Figure 4c shows the part of the results which are statistically significant at the 10% level.
A value of this analysis is that it not unreasonable to anticipate the reversal of the colors on the chart 4c if the PDO has indeed gone positive. Recently, there have been very high readings of this index but I am not at all convinced that the climate shift has taken place and in fact I think it is too soon and that the recent high readings are a result of the near El Nino Modoki Type II in the Pacific. But that is speculation on my part since I think that most people who are knowledgeable about oceans cycles are fairly convinced that they are easier to identify after they occur than to predict. But a switch to PDO+ will occur sooner rather than later. Later in this report, there is a discussion where I discuss the logical conclusion as to when the PDO will shift based on the work of some other researchers. I have also made my own assessment of when the Pacific will shift. My analysis is purely statistical and I arrive at an estimate of 5 - 20 years with perhaps 10 to 15 years being the most likely time for the next peak of the PDO Index. Some believe the shift has already begun.
It is important to remember that the PDO and IPO are oscillations not regular cycles and most likely represent three or more separate phenomena. The Aleutian Low may have its own cycle. The Kuroshio-Oyashio Extension (KOE) may exhibit cyclical behavior. ENSO is a well known cycle. Some of these cycles may be impacted by the AMO. There is a South Atlantic version of the AMO also. So the PDO and IPO may be a combination of cycles with different wavelengths. So a change in the Pacific may take many different forms and occur in an irregular manner. The below graphic shows the differences over a multi-year period. One could view the analysis by year and see how it is impacted by the ebb and flow of the situation in the Pacific but it would be difficult to interpret that amount of data so this approach is easier to interpret but we should recognize that the conditions in the Pacific are not binary but vary and not in a totally regular way.
The following is from the Summary and Conclusions Section of their paper:
How Might we Predict the Future State of the PDO and AMO and other Ocean Cycles?
A new paper is out. Unfortunately I can only access the abstract. Some with subscriptions may find the full paper here.
Klöwer et al. (2014) Atlantic meridional overturning circulation and the prediction of North Atlantic sea surface temperature.
The conclusions of this paper are more or less in line with the recent IPCC AR5 WG1 Report which failed to detect appreciable slowing of the North Atlantic Meridional Overturning Circulation (NAMOC). Most believe that this means that we have not yet seen the lengthening of the AMO. At this point it is useful to mention that most refer to these ocean cycles as oscillations as they are not as regular as the shape of a true cycle but the choice of terminology is a matter of style as the "business cycle" is also not very regular but we use the term cycle to describe it. I believe that if we become more comfortable that the AMO and PDO are regular occurrences they will increasingly be referred to as cycles.
And then there is this paper.
On the observed relationship between the Pacific Decadal Oscillation and the Atlantic Multi-decadal Oscillation Department of Atmospheric and Oceanic Sciences, University of Wisconsin-Madison, Madison, USA; Laboratory of Climate, Ocean-Atmosphere Studies, Department of Atmospheric and Oceanic Science, Peking University, Beijing, China
Another cycle of interest is the East Asian Surface Air Temperature (EATS). This paper is of interest.
And here is a similar paper published in 2007.
A third paper brings the East Asian Surface Air Temperatures (EATS) into the equation. It is not just about the U.S. This paper can be found here.
From the Abstract:
Also of interest.
The top of this Figure 1 show the three ocean cycles. It may not be easy to find another such graphic. The bottom shows the results of the correlation of the various lags. I added to the Legend at the top (the bold type) to make it clearer and hopefully I did this correctly. I will provide what I did to the Author and if I got it wrong I assume I will be so informed. This is easier to undertand by looking at the following table.
I said it would be easier. I did not say it would be easy. But you can see that these are pretty hefty correlation coefficients. So one has a fighting chance at figuring out what the climate is going to be like over the next 100 years by region. The major problem is the limited amount of data that was available to do this correlation analysis and you can see that from Figure 1 above. It is the reason that the leads and lags computed in this paper for the AMO and PDO different slightly from those computed in the papers I presented two weeks ago. It is also quite possibly the reason that the IPCC has not yet included these low frequency ocean cycles in their climate models. There really is not enough data to do so. Thus the IPCC climate models are essentially useless for predicting climate for periods of time less than 100 years and yet many do so and then are surprised when the projected and observed levels of temperature and precipitation diverge. If you do not include ocean cycles in a forecasting model it will not incorporated "internal variability".
Now I attempt to put the information from the three papers together and this is what I came up with. This table relates the AMO to the PDO. So "Lead" means the AMO reaches a peak or minimum and begins to trend in the other direction in advance of the PDO beginning to change its direction (if it is positive begin to become less positive and then become negative or vice versa)."Lag" means the AMO chances direction later than the PDO which could be expressed as the PDO leads the AMO. So yes this is a difficult concept to grasp when looking at a table of numbers. For me it is more understandable when I look at a graph of the time series of the amplitudes of the surface temperature anomalies of the AMO and PDO.
* This paper decomposes the PDO into a high Frequency 20 year cycle and a low frequency presumably 60 year cycle. The above data is for the Low-Frequency Cycle and in this paper the authors also report a high correlation for the PDO lagging the AMO by 1 - 3 years. Although I show a positive correlation for this paper in the above table in regards to the AMO leading the PDO it may well be that I have not read the paper carefully enough and that the correct sign of that correlation is also negative. So I would not conclude that this paper is inconsistent with the other two.
In all cases where both low frequency and high frequency cycles were studied and reported on, I have tabulated the results with respect to the low- frequency long component of the cycle. Note that similar decompositions into sub-cycles within the most familiar duration of these cycles are done by most researchers and not just for the PDO but many believe the PDO has both a high frequency approximately 20 year cycle (possibly ENSO related) and a low frequency approximately 60 year cycle. This is possibly the reason the correlation coefficients are not totally impressive.
To better understand "leads" and "lags" I now present another graphic from the Li et al paper.
Here the authors plotted the AMO versus the PDO which was shifted back by 17 years. Notice when you do this the AMO and PDO are always in a different phase. On the other hand if you had moved the PDO ahead by 20 years they would be in the same phase. Thus the sign of the correlation coefficient may be a function of how the relationship is described e.g. if A leads B by N years, B lags A by the same N years. So the choice of terminology may be somewhat arbitrary.
Much more important if the two cycles are 74 years in duration (as seems to be indicated by the calculations performed by the Li and Luo paper), or if you prefer, 17 years is not very different than 20 years, it would appear that the four conditions:
occur approximately an equal percentage of the time i.e. 25% for each combination.This is a very important conclusion, if correct, and I believe it is supported by all three papers. This makes the McCabe et al (and I do not want to not mention Julio Betancourt who was instrumental in that work) analyis of drought probability shown above that much more valuable.
Predicting the State of Ocean Cycles Going Forward and the Impact on the Climate of the Lower 48 States.
The paper I want to discuss can be found here.
Joint statistical-dynamical approach to decadal prediction
First I want to begin with some information from this paper which explains the three most important ocean cycles.
Notice that each of the three ocean cycles tend to also influence sea surface temperatures (SST) in the other two oceans. Thus it is reasonable to conclude that the combination of the phases of the three ocean cycles impact the climate of various parts of the World.
Recently I Ialked about North America. Although the climate of North American may be influenced by all three ocean cycles as far as I know only the impact of the North Atlantic and the North Pacific has been carefully studied. So that is what I will focus on in this weekly report. But we should not forget that some of the variance observed by McCabe et al in their work might have been explained by the IOBD if it had been included.
The following Graphic from the Luo and Li paper is very interesting.
Now I have modified the above to line up some key dates in the graphics namely the beginning of decades starting from the one we are in and looking forward. The decades are numbered across the top as "1", "2", "3", "4".
The seminal work on the impact of the PDO and AMO on U.S. climate can be found here. The key maps which were presented earlier are repeated below:
You may have to squint but the drought probabilities are shown on the map and also indicated by the color coding with shades of red indicating higher than 25% of the years are drought years (25% or less of average precipitation for that area) and shades of blue indicating less than 25% of the years are drought years. Thus drought is defined as the condition that occurs 25% of the time and this ties in nicely with two combinations of AMO and PDO phases i.e. four combinations.
In reality there are more than four combinations since for example AMO positive can cover years where the index is just barely positive to the years where the index is most positive. That may be possible to deal with using a software package but working with maps averaging the years where the indicated combination occurred makes for a more convenient way to display information but does not reflect that there is a continuum of combinations of two indices.
So combining the work of McCabe et al with the work of Lou and Li , what can we say about these beginning years in the decade which started in 2014 and subsequent decades out into our future?
This was clearly AMO+/PDO-. This is McCabe Condition D and full explains the approximately twice a century severe drought in the Southwest and also in the Great Lakes area.
This might be PDO+/AMO+ to AMO Neutral. This might be somewhere between McCabe A and McCabe C but closer to McCabe C. McCabe C is associated with extreme drought in the Northern Tier west of the Great Lakes. McCabe C also is associated with a high probability of drought in the South Atlantic Coast states extending into the Mid-West.
PDO-/AMO Neutral. This might be somewhere between McCabe B and McCabe D. Note the IPO (which I am using as a surrogate for the PDO) is forecast by Lou and Li to be less negative at its low point presumably due to the combination of subcycles with different amplitudes within the IPO. Also notice the significant difference between McCabe B and McCabe D. This illustrates the importance of the Atlantic SST's
PDO+/AMO Neutral. This might be somewhere between McCabe A and McCabe C. McCabe C seems to flip drought in the West from south to north. So McCabe A and McCabe B both spare the Southwest but the condition of the Atlantic may have a big impact on the Northern Tier west of the Great Lakes. McCabe C also is associated with a high probability of drought in the South Atlantic Coast states extending into the Mid-West.
5. And dare we project out to say 2050? This might be PDO?/AMO-. That might result in conditions intermediate to McCabe A and McCabe B. McCabe B would raise the risk for drought in the Southeast including moderate probability of drought in Florida and small areas of extreme drought in other places.
I have not tried to interpret the implications for each state in the Lower 48. The McCabe et al analysis is a mathematical analysis based on historical data. Underlying the data are climate patterns determined by mountains and interactions with Canada and Mexico. If I better understood all of these patterns I would feel more confident in making predictions state by state. I am hoping that my experiment with combining the emerging information on ocean cycles with the work of McCabe et al and similar will inspire others to undertake more work in this area.
Now let us focus on the AMO.
This is a good time to discuss the Atlantic Decadal Oscillation or AMO. It has big impact on CONUS summer weather especially precipitation and we will be disussing this more in the weeks ahead. This is from the paper Variations in North American Summer Precipitation Driven by the Atlantic Multidecadal Oscillation QI HU,SONG FENG, AND ROBERT J. OGLESBY discussed below. But here is the link if you want to reference it now.
First this paper focusing on winter impacts:
Imprint of the Atlantic multi-decadal oscillation and Pacific decadal oscillation on southwestern US climate: past, present, and future Petr Chylek, Manvendra K. Dubey, Glen Lesins, Jiangnan Li, Nicolas Hengartner
Special Note: This paper by Chylek et al. explains a common error in many climate studies including a recent analysis performed by the U.S. Bureau of Reclamation titled Upper Rio Grande Climate Assessment. It is likely that his sort of error is very prevalent in many reports because the researchers are not sufficiently familiar with what the IPCC calls internal variability. Recent focus on what has been called the Warming Hiatus has called attention for the need of researchers to become familiar with the impact of the major ocean cycles on climate or alternatively at least detrend the temperature data.
The Chylek et al paper is focused primarily on winter climate in the Southwest and to me it in many ways is a redo of the McCabe et al analysis but I do not believe the authors see it that way based on their reference list. I do believe their findings are similar which does not come as a surprise.
There are two theories on what controls summer precipitation. This paper is a good explanation of how summer precipitation is controlled by the Atlantic and in particular the AMO.
Variations in North American Summer Precipitation Driven by the Atlantic Multidecadal Oscillation QI HU,SONG FENG, AND ROBERT J. OGLESBY
Some of the graphics from this paper are extremely interesting so I am showing them. You can enlarge them here and here. The way to look at this graphic is that the situation for the AMO being in its warm phase is shown on the left and the situation for the AMO being in its cool phase is shown on the right. The top graphic represents the upper troposphere and the bottom graphic the lower troposphere.
It is amazing to me that the patterns in the upper and lower troposphere can be so different but the easiest explanation perhaps is that the stronger/larger/and 20 degrees of longitude further west Bermuda High (also known as NASH, Azores High) associated with AMO- results in the jet stream being shifted further north and creating a counter-clockwise/cyclonic curvature which is conducive to storm formation.
The AMO has been positive since the mid nineties and peaked around 2010 or a bit earlier and is now pretty much neutral but we will be in AMO negative soon and for a long time. It might be useful to better understand how the Atlantic Multidecadal Oscillation presents itself and the following table presents some information which comes from an excellent paper by Iris Grossmann and Philip J. Klotzbach which can be found here.
It is only one paper so it may not be correct but it certainly is provocative. Between the two papers it points out the need to be able to either:
A. Forecast the AMO and PDO or
B. Develop a set of reasonable scenarios for how they might vary over time.
I have done that a little earlier in this report so therefor: I DO NOT KNOW HOW TO MAKE IT ANY CLEARER. THE AMO WILL BE BECOMING LESS POSITIVE AND SHIFT TO AMO NEGATIVE AND THE PDO WILL SOON BECOME PDO POSITIVE IF IT HAS NOT ALREADY DONE SO. The AMO has been positive since the mid nineties and peaked around 2010 or a bit earlier and is now pretty much neutral but we will be in AMO negative soon and for a long time. It might be useful to better understand how the Atlantic Multidecadal Oscillation presents itself and the following table presents some information which comes from the Iris Grossmann and Philip J. Klotzbach paper.
* These locations are really associated with the NAO rather than the AMO but I think they are fairly similar and I will continue to research this. But the key point is that both the AMO and NAO tend to show up as a tripole i.e. three different areas of temperature anomalies. At any rate it is more complicated than some presentations that describe it as a uniform warming or cooling of the Atlantic. There is a third cycle called the Atlantic Meridional Mode AMM which relates mostly to the differential strength of the Trade Winds north and south of the Equator. One can understand why Climate Change models have difficulty incorporating these ocean and air pressure cycles. Of course that means these models are not very reliable for forecasting intervals shorter than 100 years.
East Asian Surface Temperature Oscillation (EATs)
Now that I have introduced the topic of the East Asian Surface Temperature Cycle, this paper is of interest.
Is El Nino and the AO or NAO correlated to any significant extent?
Beginning with this article. From the Abstract
And from an article in the American Meteorological Society:
So it would appear that there may be some correlation of an El Nino and negative NAO with the direction of causality being from the ENSO process to the occurence of a negative NAO. It does seem that the development of the El Nino and its intensity and location will impact the intensity and duration of a possible negative NAO but lagged from the initiation of an El Nino or La Nina.That may be important for the U.S. East Coast and Northern Europe
I have been asked why computer models are not perfect. Here are two good reasons:
1. The model is incomplete. This can occur for two reasons:
This article also might be of interest in terms of background on the history of the development of weather forecasting models.
Of course there has been much progress since then but you get the idea that one has to be able to describe the current conditions of the atmosphere (and land and ocean surfaces) to be able to make forecasts.
One approach to deal with lack of data is to extrapolate missing data using equations that estimate the missing data based on the actual observations. That provides a way to initialize a model. An improvement on that is to vary the estimates of the initial conditions (consistent with the distribution of variations in the real world and there is the rub) and run the models to see how sensitive the models are to small changes in the estimates of the initial conditions. This is one version of "ensembles" a fancy word for a collection of related things. You can have an ensemble of different initial conditional assumptions or an ensemble of slightly different models and the "spread" of the solutions is assumed to be a measure of the confidence one should have in the forecasts. I leave it to the reader to decide if that approach is consistent with how they arrive at confidence about the future. I am not saying that there is a better approach, but I am saying that if the model is wrong and "sensitivity" analysis indicates that small changes in assumptions or internal formulae for parametrization do not cast doubt on the forecast, that forecast will still be less than useful if the model itself is incomplete or just plain wrong.
Sufficient computational capacity is also important. Here is a blog post on that topic, which is a little out of date, but purports to describe the situation in the U.S. It is possible that some of the issues discussed in that blog post have been addressed since it was written, but my experience is that other nations lead the U.S. If you do not like the situation, talk to Congress. NOAA needs to be reorganized, streamlined, given new leadership and then provided adequate funding. Part of the situation is a result of the decision to provide opportunities for the private sector and not have the Federal solution so comprehensive that there was no room for the private sector to add value. It is a delicate balancing act.
2. The model is based on historical data but the situation has changed.
Thus the model continues to interpret the inputs as they should be interpreted consistent with the situation at the time the data was collected. Hence my conclusion that computer models essentially "predict the past not the future" which could be reworded to be less inflammatory as models "predict the future in the same way they would have predicted a similar situation in the past and thus their prediction of the future is essentially the same as predicting the past".
From a mathematician's perspective, a relationship is valid only if the domain of samples used in the creation of the model includes the values used in the running of the model. From a practical perspective, you have no way to calibrate and test such a model if you have no data for situations faced that have never been faced before. We run into this problem with Climate Change models. The domain of data does not include carbon dioxide concentrations of 400 PPM or average temperatures greater than what we had for the last thirty years.
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