November 10 Weather and Climate Report - El Nino May be Arriving Soon

November 11th, 2014
in econ_news

Written by

Looks like the Southern Oscillation has decided to cooperate in the development of an El Nino. At this point it looks weak and, of course, late. The big question now is what kind of El Nino and is this a one-year or two-year event. A big chill is coming to the North Central Lower 48 and extending southward.

Follow up:

NOAA has reduced their probability of an El Nino to 58% but this analysis actually appears to me to be more sound than their prior enthusiasm. More on that later.

I think the best way to get started is to take a look at the 6 -14 Day Outlook that was issued today November 10, 2014.

I am only showing the "second week" map namely the day 8 -14 outlook. The first week map can be found in Part II of my report but 8 - 14 days covers most of the 6 - 14 day period and does not vary much from the first part of the outlook issued today.

Here is the Temperature Outlook for November:

Nov 2014 Final Temperature Outlook

And here is the 8- 14 Day Outlook issued today.

Temperature forecast 814

There is not much resemblance other than in the West between the third week of the month outlook and the previously issued monthly outlook. It has been that way all month.

Moving to Precipitation, here is the November Precipitation Outlook:

November 2014 Final Precipitation Outlook

And here is the 8 - 14 Precipitation Outlook Issued today.

Precipitation Forecast 814

There is some similarity here with the previously released Monthly Outlook but not a lot.

Here are excerpts from the NOAA discussion which today is quite long.

6-10 DAY OUTLOOK FOR NOV 16 - 20 2014

TODAY'S MODEL SOLUTIONS ARE IN EXCELLENT AGREEMENT IN PREDICTING A VERY AMPLIFIED 500-HPA FLOW PATTERN OVER MOST OF THE FORECAST DOMAIN. THE MODELS AGREE IN PREDICTING TROUGHS OVER THE BERING SEA/ALEUTIANS AND NEAR HUDSON BAY/THE EASTERN AND CENTRAL CONUS. AN AMPLIFIED RIDGE IS FORECAST ALONG THE WEST COAST OF NORTH AMERICA, EXTENDING NORTHWESTWARD TO EASTERN ALASKA. THE DETERMINISTIC RUNS FROM THE GFS AND ECMWF ARE GENERALLY IN GOOD AGREEMENT WITH THEIR RESPECTIVE ENSEMBLE MEAN SOLUTIONS, ALTHOUGH THE DETERMINISTIC SOLUTIONS DEPICT SOME TROUGH ENERGY UNDERCUTTING THE RIDGE FORECAST OVER THE WESTERN CONUS.

THE ENSEMBLE SPAGHETTI DIAGRAMS GENERALLY INDICATE LOW SPREAD OVER THE EASTERN AND CENTRAL CONUS, AND MODERATE SPREAD OVER THE WESTERN CONUS AND EASTERN PACIFIC. THE SPREAD IN THE SOUTHERN JET STREAM SEEMS RELATED TO HOW MUCH TROUGH ENERGY WILL UNDERCUT THE RIDGE EXPECTED OVER THE WESTERN CONUS. THE PNA INDEX WHICH RECENTLY HAS BEEN POSITIVE IS FORECAST TO REMAIN POSITIVE THROUGH DAY 14. THE NAO INDEX WHICH RECENTLY HAS BEEN CLOSE TO ZERO IS EXPECTED TO BE NEGATIVE BY DAY 7, AND REMAIN SLIGHTLY NEGATIVE THROUGH DAY 14

Editors note: Typically a negative NAO would suggest stormy weather for Northern Europe but at this point in time it seems like more of a North American event.

TODAY'S MANUAL 500-HPA HEIGHT BLEND INDICATES NEAR TO ABOVE NORMAL HEIGHTS OVER ALASKA AND THE PACIFIC NORTHWEST, AND NEAR TO BELOW NORMAL HEIGHTS OVER THE REMAINDER OF THE CONUS AND THE ALEUTIANS.

THE DEEP TROUGH PREDICTED OVER EAST-CENTRAL NORTH AMERICA STRONGLY FAVORS BELOW NORMAL TEMPERATURES FOR MOST OF THE CENTRAL AND EASTERN CONUS. FORECAST RIDGING ALONG THE WEST COAST FAVORS ABOVE NORMAL TEMPERATURES FOR MUCH OF THE SOUTHWESTERN CONUS. ABOVE NORMAL TEMPERATURES ARE ALSO FAVORED FOR ALASKA UNDERNEATH ANOMALOUS SOUTHERLY FLOW AHEAD OF THE TROUGH PREDICTED OVER THE BERING SEA/ALEUTIANS.

MOIST FLOW AHEAD OF THE PREDICTED BERING SEA TROUGH FAVORS ABOVE MEDIAN PRECIPITATION FOR PARTS OF THE EASTERN ALEUTIANS AND SOUTHWESTERN COASTAL ALASKA. ABOVE MEDIAN PRECIPITATION IS FAVORED FOR PARTS OF THE WESTERN AND WEST-CENTRAL CONUS AS THE DETERMINISTIC MODEL SOLUTIONS INDICATE SHORT WAVE ENERGY UNDERCUTTING THE RIDGE FORECAST OVER WESTERN NORTH AMERICA. PROBABILITIES OF BELOW MEDIAN PRECIPITATION ARE ALSO ENHANCED FOR PARTS OF THE NORTHERN PLAINS, UPPER AND MIDDLE MISSISSIPPI VALLEY, TENNESSEE VALLEY, AND THE INTERIOR NORTHEAST DUE TO SUBSIDENCE ASSOCIATED WITH THE TROUGH PREDICTED OVER THE EAST-CENTRAL CONUS. THERE IS THE POTENTIAL FOR A GULF COAST STORM TRACK AHEAD OF THE TROUGH AXIS RESULTING IN ENHANCED PROBABILITIES OF ABOVE MEDIAN PRECIPITATION ALONG THE GULF COAST AND PARTS OF THE SOUTHEAST CONUS. RIDGING OVER ALASKA FAVORS BELOW MEDIAN PRECIPITATION FOR MUCH OF CENTRAL AND NORTHERN ALASKA. CYCLONIC FLOW AT THE SURFACE AND ALOFT ENHANCES PROBABILITIES FOR ABOVE MEDIAN PRECIPITAION FOR MUCH OF THE GREAT LAKES REGION. RIDGING OVER THE WESTERN CONUS ENHANCES PROBABILITIES FOR BELOW MEDIAN PRECIPITATION FOR PARTS OF THE INTERIOR SOUTHWESTERN CONUS.

FORECAST CONFIDENCE FOR THE 6-10 DAY PERIOD: MUCH ABOVE AVERAGE, 5 OUT OF 5, DUE TO GOOD MODEL AGREEMENT AND A PREDICTED AMPLIFIED PATTERN.

8-14 DAY OUTLOOK FOR NOV 18 - 24 2014

TODAY'S WEEK TWO MODEL SOLUTIONS ARE IN GOOD AGREEMENT ON THE 500-HPA FLOW PATTERN OVER NORTH AMERICA AND ARE SIMILAR TO THAT PREDICTED FOR THE 6 TO 10 DAY PERIOD, ALTHOUGH SOME DEAMPLIFICATION AND PROGRESSION OF THE DEEP TROUGH OVER THE EASTERN AND CENTRAL CONUS IS INDICATED. TROUGHS ARE PREDICTED OVER THE BERING SEA/ALEUTIANS AND OVER EASTERN NORTH AMERICA, WHILE RIDGING IS FORECAST OVER THE PACIFIC NORTHWEST AND EASTERN ALASKA. THE ENSEMBLE SPAGHETTI DIAGRAMS GENERALLY INDICATE LOW SPREAD OVER THE EASTERN AND CENTRAL CONUS, AND MODERATE TO LARGE SPREAD OVER THE WESTERN CONUS AND EASTERN PACIFIC.

TODAY'S WEEK TWO MANUAL 500-HPA BLEND INDICATES NEAR TO ABOVE NORMAL HEIGHTS OVER THE WESTERN QUARTER OF THE CONUS AND ALASKA, AND NEAR TO BELOW NORMAL HEIGHTS OVER THE EASTERN THREE QUARTERS OF THE CONUS AND THE ALEUTIANS.

THE EXPECTED TEMPERATURE AND PRECIPITATION ANOMALY PATTERNS FOR WEEK 2 ARE QUITE SIMILAR TO THOSE FORECAST FOR THE 6-10 DAY PERIOD EXCEPT FOR A SLIGHT EASTWARD PROGRESSION FOR MOST OF THE ANOMALY CENTERS DURING WEEK 2."

Analogs to Current Conditions

Now let us take a more detailed look at the "Analogs" which NOAA provides related to the 5 day period centered on 3 days ago and the 7 day period centered on 4 days ago. "Analog" means that the weather pattern then resembles the recent weather pattern and was used in some way to predict the 6 - 14 day Outlook.

What are they telling us today?

Analog

Centered

Day

ENSO

Phase

PDO AMO Other Comments
1951 October 30
El Nino
- +

1951 November 2
El Nino - +

1957 November 23
El Nino
- + Probably a Modoki
1957 November 24
El Nino
- + Probably a Modoki
1959 November 24
Neutral
-
+
1962 October 22
Neutral
- +
1992 November 13
Neutral
+ - Right after an El Nino
1993 October 25
Neutral
+ -
1995 October 27
Neutral
+ +

The analogs are now providing a somewhat neutral picture and is no longer presenting as La Nina conditions.  They do, however, reflect PDO negative conditions even though the PDO is positive. In fact the majority of the analogs are associated with periods of time when the condition of the oceans was PDO-/AMO+ which is associated with weak El Ninos. 

If we were already in El Nino conditions, the weather patterns around the world would be more like the below. We do see some of that in Australia but not so much in the U.S. but one can argue the point.

El Nino Precipitation


El NinoTemperature

El Nino Discussion

From Australia:

Warm Tropical Pacific Ocean, but ENSO remains neutral

Issued on Wednesday 5 November 2014

Overall, the El Niño–Southern Oscillation (ENSO) remains neutral. Sea surface temperatures in the tropical Pacific Ocean have warmed over the past two months, and the Southern Oscillation Index has remained negative, but indicators generally remain in the neutral range. The existence of warmer-than-average water in the tropical Pacific sub-surface supports a continuation of the current near-El Niño conditions.

International climate models surveyed by the Bureau suggest that warmer-than-average tropical Pacific sea surface temperatures are likely to persist. Three of eight models reach El Niño thresholds in January 2015, and two remain just shy of thresholds. Australian rainfall and temperature patterns show some El Niño-like impacts, with the country generally warmer and drier than usual over recent months. Warmer central tropical Pacific waters late in the year typically result in warmer and drier weather for parts of eastern Australia, an increase in bushfire risk in the south, and average to below-average numbers of tropical cyclones in the Australian region.

The Indian Ocean Dipole (IOD) is neutral. The IOD typically has little influence on the Australian climate from December to April."

But I do note that their proprietary model which is available in Part II of this Report has shown movement much closer to predicting an El Nino. Since that model was run on November 2, I am a bit surprised that this statement is not more positive for an El Nino than it is.

Now let us look at the latest NOAA Hovmollers.

First Sea Surface Temperatures

Nov 10, 2014 SST

Over to the left side of the graphic at 160E at the bottom you can see where there had been some warming surface water. It is now there again and does appear to be moving east. Also you can see what was just hinted at two weeks ago which is some warmer water in the Eastern part of the Equator which is significant for an El Nino. But it is still not enough yet but evolving in a positive direction for an El Nino.

And now the low-level wind anomalies.

Nov 10, 2014 Low Level Wind Anomaliies

We had a westerly anomaly three weeks ago that could do something and apparently it did. Is that enough to actually have an El Nino with enough strength to have an impact? the Hovmoller looks positive for an El Nino but still not very impressive.

The Southern Oscillation Index (SOI) has definitely this past week been cooperating. You can find the daily and 30 and 90 day averages here. With the SOI there is always a cause and effect issue. Is the SOI a cause of or a result of warm water being to the east? The SOI is an imperfect index as the two reference points are not on the Equator but I will not go into that today. The 30 day average is now indicative of El Nino conditions. Today's reading is -16.86 which is an El Nino reading and the SOI has been very negative (good for El Nino) the entire past week. Of course the SOI can change very quickly.

And then the third part of the equation (there are more than three but I focus on three): Kelvin Waves.

November 10, 2014 Kelvin Waves

And here we do have a signal of warm water moving east but:

  • the prior Kelvin wave has played out and is no longer shown on the Equator. Thus it is no longer contributing to the creation of an El Nino.
  • now NOAA shows an upwelling wave (dotted line) but it was more of a neutral to warming situation rather than a normal cooling upwelling wave. Thus we currently are in a situation with warm water arriving from this sort of activity but it is below the level required for an El Nino.
  • and then there is the newest Kelvin wave. It appears to be about the same intensity or perhaps a bit more than the prior wave which has played out but curiously might be proceeding a bit more slowly (visual analysis of the slope of the lines drawn by NOAA). It is not that this Kelvin Wave could not trigger an El Nino, but it does seem to me that we are not talking about November for this to have a significant effect.

I believe that this Kelvin Wave and the tendency to have repeated Kelvin waves is the reason for continued optimism that we will have an El Nino this year but it will be unusually late arriving if it arrives at all.

I still do not see a traditional El Nino of any significant strength likely to happen this winter, especially the first half of the winter. It appears to be a very complicated situation. There are many possibilities on the table in my opinion:

  • A short weak traditional El Nino which arrives late. That appears to be the NOAA forecast.
  • A weak traditional El Nino arriving late but being reinforced and turning into a long lasting stronger traditional El Nino. (Not forecast by NOAA but not inconsistent either) This would be somewhat like the 1982/1983 Super El Nino.
  • A weak traditional El Nino that turns into a Modoki next year (The Japanese Forecast)
  • Nothing much at all at least until next summer (seems to be where the Australia model was headed but they are now inching towards a more positive outlook - which is actually negative for them as they do not benefit from an El Nino)
  • Other variations of the above all related to warmer water further east than usual in the ENSO cycle but not necessarily translating into the usual El Nino that would normally be here now if it fit the usual mold.

And one more graphic for good measure.

Nov 6 CPC-IRI ENSO Outlook

This is the analysis that NOAA depends on. Notice the probability of an El Nino has been reduced to 58% which I believe is a reasonable estimate unlike their prior estimates. Notice that May is about the point where this set of models suggest that El Nino is more likely than neutral. That might be about a month later than the long term forecast has shown in their maps (my interpretation) so we may see that adjustment in the new Long-Term Outlook that will be issued on November 20. Other models show the potential for El Nino conditions to actually strengthen going into the summer. So there is clearly a difference of opinion within the meteorology community as to how this will evolve.

Oceans.

Two weeks ago, I presented papers that discussed the relationship between the PDO and the AMO. This is important because of the major impact these cycles have on our weather. There is also more information available on the AMO and when it might change phase from positive to negative. In this regard, last week I presented a paper that discussed the progression of the AMO. 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.

Highlights:
• North Atlantic sea surface temperature exhibits high decadal predictability potential.
• Model bias hinders exploiting the decadal predictability potential.
• An innovative method was developed to overcome some of the bias problem.
• North Atlantic sea surface temperature will stay anomalously warm until about 2030.

Abstract:
The Atlantic Meridional Overturning Circulation (AMOC), a major current system in the Atlantic Ocean, is thought to be an important driver of climate variability, both regionally and globally and on a large range of time scales from decadal to centennial and even longer. Measurements to monitor the AMOC strength have only started in 2004, which is too short to investigate its link to long-term climate variability. Here the surface heat flux-driven part of the AMOC during 1900–2010 is reconstructed from the history of the North Atlantic Oscillation, the most energetic mode of internal atmospheric variability in the Atlantic sector. The decadal variations of the AMOC obtained in that way are shown to precede the observed decadal variations in basin-wide North Atlantic sea surface temperature (SST), known as the Atlantic Multidecadal Oscillation (AMO) which strongly impacts societally important quantities such as Atlantic hurricane activity and Sahel rainfall. The future evolution of the AMO is forecast using the AMOC reconstructed up to 2010. The present warm phase of the AMO is predicted to continue until the end of the next decade, but with a negative tendency.

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 Journal of Oceanography (Impact Factor: 1.46). 01/2011; 67(1):27-35. DOI: 10.1007/s10872-011-0003-x

ABSTRACT We studied the relationship between the dominant patterns of sea surface temperature (SST) variability in the North Pacific
and the North Atlantic. The patterns are known as the Pacific Decadal Oscillation (PDO) and the Atlantic Multi-decadal Oscillation (AMO). In the analysis we used two different observational data sets for SST. Due to the high degree of serial correlation in the PDO and AMO time series, various tests were carried out to assess the significance of the correlations. The results demonstrated that the correlations are significant when the PDO leads the AMO by 1 year and when the AMO leads the PDO by 11–12 years. The possible physical processes involved are discussed, along with their potential implication for decadal prediction."

Of course the correlation coefficients in the above paper are under 0.5 on an individual lag period basis so although the argument for a somewhat predictable lag is strong the exact number of years is far less certain. The above paper was published in 2010. I am not sure how to integrate the two papers. Figure 1 in the paper is confusing to me so I have to sort that out. Have they plotted the PDO in reverse i.e. negative Phase plotted as a positive number? If so then it makes sense. The PDO would appear to be possibly switching from negative to positive.

And here is a similar paper published in 2007. Both papers are excellent in that they attempt to explain the mechanism for the synchronization not just depend on mathematical analysis. In this paper, the most highly correlated lag is 13 years.

Today I want to present a third paper that 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:

"The authors analyzed the lead-lag connection of the Atlantic Multidecadal Oscillation (AMO) with East Asian surface air temperatures (EATs) using instrumental records, and compared the results with the Pacific Decadal Oscillation (PDO). The maximum correlation was found when EATs led the AMO by five to seven years (with a correlation coefficient of 0.72, whereas the correlation coefficient was −0.91 when the AMO led EATs by 24–28 years). This is different from the PDO, which mostly correlated with EATs when the PDO led EATs by 13–15 years (with a correlation coefficient of 0.67, whereas the correlation coefficient was −0.76 when EATs led the PDO by 24–26 years). The PDO led the AMO by 19–21 years (with a correlation coefficient of 0.71, whereas the correlation coefficient was −0.84 when the AMO led the PDO by 16–18 years). These results support a previous understanding that EATs positively correlate with the AMO, and imply that the observed East Asian warming trend may have been slowing down since the early 2010s."

Also of interest.

EATS Table 1 Revised

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.

EATs Lag Table 1

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.

AMO relationship to the PDO re Leads and Lags
Lead Lag

Sum of Absolute Values of the Lead and Lag

Twice the number in the prior column
Orgeville and Peltier -13 +17 30 60
Wu, Liu, Zhang and Delworth* 12 to 14 12 to 13 26 52
Li and Luo -(16 to 18) 19 to 21 37 74

* 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. 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.

I hope I got the Authors' names correctly. I have difficulty sometimes with Chinese names being sure which is the last name. Figuring out the sign of the correlation was difficult and I may have gotten it wrong. Notice I am reporting that one paper, Wu et al, indicated that the AMO leads the PDO by 12 to 14 years but with a positive correlation. That is different than the other two papers so I am puzzled by it. I may have misinterpreted the paper but note that the sum of the absolute values of the leads and lags are roughly similar for all three papers.

To better understand "leads" and "lags" I now present another graphic from the Li et al paper.

AMO and PDO shifted back by 17 years

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:

  • AMO+/PDO+
  • AMO+/PDO-
  • AMO-/PDO+
  • AMO-/PDO-

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, even the one that appears to show both the leads and lags positively correlated (because the reported leads and lags are roughly of the same magnitude). 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 that much more valuable.

Their key maps are shown below:

-McCabe Drought AMO/PDO

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.

A caveat of all of this is that this lead/lag correlation analysis approach forces the PDO and AMO to have the same duration (for the leads and lags to remain consistent over time). Most but not all researchers report the AMO as having a longer duration than the PDO. But if you look at one of the graphics above you can see that we do not have a lot of data to work from. Also the definition of the AMO and PDO by different researchers can be different. The main (but not the only) difference is that some use annual data and others use averaging to smooth the annual data. So the peaks and valleys might differ a bit from research team to research team. It is likely that this does not create a big difference in the results.

Based on these three papers and by simply looking at the graphics when the AMO and PDO and EATS are plotted, it seems to me that these cycles are fairly highly correlated and this can be used to predict the future. I am also fairly convinced that the AMO drives the PDO the theory being that the AMO is mostly North Atlantic Meridional Overturning Circulation (the Thermohaline Circulation is one part of the NAMOC). When you have such a phenomenon in the North Atlantic, it is reasonable that all other oceans have to adjust to balance things out.

The following graphic from the Wu et al paper showing the principle component of the PDO (Blue line) and the AMO (red line) shows how different methodologies can arrive at different conclusions on the sign of correlation.

We et al Figure 1e.

As you can see in this case the author has done less filtering and smoothing and you can see periods where the two cycles are in sync and periods where they are out of phase. That is why the correlation analysis does not produce correlation coefficients close to 1.0. So the lead and lag analyses should not be looked at as a way to make 100% valid projections but rather as a way of prediction the most likely timing of the changes in phase of these cycles. Its use in scenario planning may actually be the better approach for a number of reasons that I will not go into now as this report is already much longer than usual.

At this point this type of information is not yet built into the IPCC models nor is it often used. The Bureau of Reclamation (BOR) Upper Rio Grande Report Impact Assessment issued fairly recently suffers from the authors not understanding internal variability and how to deal with it. I imagine there are many climate studies out there that suffer from this deficiency. It is about time that those working in this field brought themselves up to date on the literature which really is simply analysing the data that is readily available. There is no excuse for those who have ignored this. I certainly have not fully figured this out as of yet as is clear from this discussion but at least I am trying to do so.

Click Here for the Econointersect Weather and Climate Page where you will find:

  • NOAA and other agency graphics (including international agencies) that auto update. So this includes both short term- and seasonal "updates". It will ALWAYS be up to date even if my commentary on the graphics is not. I update my commentary when it seems necessary and certainly every Monday but some of these graphics auto update every six hours. This section of the report has been reorganized to make it easier to follow.
  • Economic and other Impacts of major weather events. Not sure there is any other place to obtain this information consistently other than very specialized subscription services.
  • Information on Climate Cycles both those which are fairly short term i.e. less than a decade in duration and multi-decadal cycles.
  • Economic and other Impacts of those Climate Cycles which are referred to by the IPCC as Internal Variability as opposed to secular Climate Change which is always in the same direction. Again I am not sure if there is another source for this information where it is pulled together in one place as I have.
  • Information on Anthropogenic Global Warming science i.e. the secular change in our climate that overlays both short term weather and historical climate cycles as well as black swan events like volcanic eruptions. I prefer to call this Global Warming as it is the warming that triggers the other changes.
  • Economic and other Impacts of Global Warming. The IPCC AR5 WG2 attempts to describe and quantify these and I have some excerpts from their report. Over time I will go beyond their report.

For now this is all in one article which may be a little difficult to navigate but that will soon change and the information will be accessed easily by topic. Towards that end I have added a Table of Contents.

 









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