March 2020 Seasonal Forecasts. Part II, NOAA Comparison with JAMSTEC

Written by Sig Silber

We published the NOAA Long-Term Forecast Friday Night. Here we compare the NOAA forecast for Alaska and CONUS with the JAMSTEC forecast. Also provided are the JAMSTEC World Forecasts with special emphasis on Europe. As usual, the two forecasts are not in agreement especially in terms of Spring and Fall temperature and Summer and Fall Precipitation. JAMSTEC seems to be calling for a decent Monsoon and also a wet Central Plains and even the Northern Plains.

Please share this article – Go to the very top of the page, right-hand side for social media buttons. Please feel free to send this article to anyone who you think might find it interesting and or useful.

Comparison of the NOAA and JAMSTEC Forecasts Plus the Extracted JAMSTEC Europe Forecast.

Below (in what I call the “Summary”) is the comparison of the NOAA and JAMSTEC temperature and precipitation forecasts for three time-periods and from left to right the NOAA forecast for Alaska and CONUS (the contiguous mid-latitude U.S), then JAMSTEC for North America (which includes Canada and Mexico), and then we also provide JAMSTEC for Europe and surrounding areas which this week seems to include most of Eurasia. The NOAA forecasts can be clicked on to enlarge*. The JAMSTEC graphics in the Summary Table are not set up to be clicked on to enlarge (because we have no larger version of them). We have concluded that these smaller images work fine for comparison purposes. Later in the article, we show the World Forecasts.

* If for some reason that does not work, right-click and then click on view image and that should work. I checked it for all the NOAA images and four work by clicking on them and the other two will work if you right-click and then click view image. There are many mysteries to the Internet.

JAMSTEC works with three-month seasons as they view Spring as MAM (meteorological Spring) so from their perspective, it is time to focus on Spring MAM, Summer JJA, and Fall SON. Out of each three months, there is one where the months in the two forecasts for the first time period align perfectly but this is not that month. The Spring maps for JAMSTEC are MAM and March is almost over. For NOAA we have the more appropriate AMJ maps so for Spring we are comparing the MAM JAMSTEC maps with the NOAA AMJ maps. It is not ideal but probably workable. Two of the three months are the same.

Here is the Summary of our findings. Note that we took a large snip for Europe and later realized we had almost all of Eurasia in that snip. The benefit of this is that you see most of Eurasia. The bad part is that you do not see the British Isles or Spain. I address that later but remember the full World maps are in his article so you can scroll down and find anything that is missing. We hope that what was gained exceeds what was lost.

Temperature

	NOAA Alaska Plus CONUS	JAMSTEC North America	JAMSTEC Europe
Spring MAM 2020 for JAMSTEC AMJ for NOAA
Summer JJA 2020
Fall SON 2020

Precipitation

	NOAA Alaska Plus CONUS	JAMSTEC North America	JAMSTEC Europe
Spring MAM 2020 for JAMSTEC AMJ for NOAA
Summer JJA 2020
Fall SON 2020

We provided the full NOAA Discussion in Part I. The much shorter JAMSTEC Discussion was published on March 12, 2020, and we included it in Part I but we are repeating it here also. Here we mostly highlight points that do not impact Alaska or CONUS as we have discussed them above.

ENSO forecast:

As predicted earlier, the El Nino Modoki-like state has started to decay. The SINTEX-F predicts that the tropical Pacific will return to a neutral-state from summer.

Indian Ocean forecast:

Now, the eastern tropical Indian Ocean is warmer-than-normal. The model predicts the evolution of a moderately positive Indian Ocean Dipole from boreal summer. However, there is a large uncertainty in the prediction (some members actually predict a negative event) at present.

As predicted earlier, the strong negative Indian Ocean Subtropical Dipole still persists although it has been decaying from January.

Regional forecast:

On a seasonal scale, the SINTEX-F predicts that most part of the globe will experience a warmer-than-normal condition in boreal spring. In boreal summer, almost all part of the globe will still experience a hotter-than-normal condition, except for northeastern Russia.

As regards to the seasonally averaged rainfall in boreal spring, a drier-than-normal condition is predicted for western U.S.A., Brazil, most part of Southeast Asia, Indonesia, Philippines, eastern Australia, and southern Africa. In contrast, eastern U.S.A., northern Brazil, central Africa, India, Sri Lanka, western China, and U.K. will experience a wetter-than-normal condition. In boreal summer, a wetter-than-normal condition is predicted for Mexico, India, some parts of Southeast Asia, Philippines, and eastern China. In contrast, California, northwestern Brazil, southern Australia, northern China, and Indonesia will experience a drier-than-normal condition. Some of them will be partly due to the expected positive Indian Ocean Dipole.

The model predicts most part of Japan will experience warmer and slightly wetter-than-normal condition in the coming spring as a seasonal average. In summer, most part of Japan will be warmer and wetter-than-normal.

JAMSTEC World Forecasts

My comments on these world forecast maps refer to areas other than Europe, Alaska, and CONUS as we have discussed those areas earlier. My comments are limited because we have the JAMSTEC discussion above which in some cases goes into more detail.

Spring which is MAM

Temperature

Not much cool here. but the waters in the Sea of Okhotsk are cool. That is an oddity. I also notice that the waters west of Alaska are cool. NOAA has also talked about a renewal of sea ice in their discussion that we published Friday Night.

Precipitation

Australia is mixed. The Philippines are dry. India is wet. Southern Africa is dry. Notice the ocean pattern in the Equatorial Pacific.

Summer which is JJA

There is not much that is cool except in Eastern Siberia and Northern Canada. There is more EC than in MAM.

Precipitation

Australia is now slightly dry. Eastern Asia is wetter. Northern South American is mostly dry. JAMSTEC does not address this but the Western Caribbean suggests the potential for cyclonic activity there.

And Fall which is SON

Temperature

Much of Asia is EC. So is Northern Africa. Again it is less warm than JJA which is less warm than MAM.

Precipitation

Australia is mixed but on the wet side, Equatorial Africa is wet, The Maritime Continent is wet. Again notice the sea surface temperature pattern in the Equatorial Pacific.

D. Conclusion

As usual, there is substantial disagreement between NOAA and JAMSTEC. It is difficult to relate the differences in the forecast to differences in assumptions on ENSO. Although the difference in the forecasts for CONUS Temperature in MAM/AMJ 2020 may be related to how the Mokoki-like condition phases out.

It may or may not be too early for NOAA to comment on the North American Monsoon but JAMSTEC does although it is difficult now to locate places down to the state level on the JAMSTEC maps. They used to show the state boundaries but no longer. Their forecast for the area that will be wet in JJA 2020 is very suggestive of good news for the western part of the Monsoon area as well as the Central Plains.

E. SINTEX gets an update.

I was surprised last month when I started working on this article to see things looking a lot different.

Here is a summary of the changes to the forecasting model. I have this month printed it out in full. Soon I will just provide the link. In the future, we may be showing not just the present forecasts but also the forecasts three-months earlier and the actual for that three-month period. The details of how we would present that information have yet to be worked out. We are still wrestling with the new JAMSTEC forecasts. We decided to use what they consider their most advanced model but it is not clear yet if the most advanced model is superior everywhere in the World. But we used it this month. The JAMSTEC maps seem to be a bit improved but not as easy to read as the prior version. It would drive me crazy to try to compare the NOAA forecast to three (actually four or soon five) different versions of the JAMSTEC model. So I selected what they consider the best but yet easier to read than the multimode version and we hope that is the most useful. Over time, we will gain more experience with this. Remember NOAA has way more than three or four models and what we see is their preferred amalgamation of all their models. JAMSTEC has that also but it was not available last month and we could have used it and perhaps will in the future. When you amalgamate models, you end up with the models not saying very much other than decadal trends. They tend to cancel each other out. For better or worse, all the JAMSTEC models are by the same agency so they have some internal consistency with each other. The model I selected F2-EDVar might be more useful when the ENSO phase is expected to change or if ocean conditions, in general, are expected to change over the forecast period. The VAR feature (modeling the different layers of the oceans) should play a role mostly in the second and third seasons of the forecast. And the new model is optimized for the Pacific which is where Japan is located. But especially in seasons other than Summer, most CONUS weather comes from the Pacific. So we expect the new model to be an improvement but it is early in its life and models improve with age as they are continually calibrated. But it seemed regressive to just stick with the no-longer maintained FI Version of SINTEX. For those who do not like our choice of model, the full suite of model results can be found here. Have fun!!!

Tropical climate variations such as El Nino/Southern Oscillation (ENSO) and ENSO Modoki in the tropical Pacific and the Indian Ocean Dipole Mode (IOD) have enormous impacts on the global climate and the human societies. Therefore, there is a significant benefit to our societies if these climate events are predicted sufficiently ahead of their occurrences. Since the mid-1980s, many research institutes and operational centers have developed various numerical prediction models for ENSO forecast. Also, the IOD and ENSO Modoki predictions are attempted by some of the leading modeling groups recently. The numerical prediction of weather has been proven to be very useful to us now days because of the superb advancements made in that area of research during last several decades. Such weather forecast systems mostly employ standalone atmospheric models on the assumption that the oceans do not change in the relatively short prediction period (~1 week). However, such standalone atmospheric models are not ideal for predictions of climate phenomena like ENSO, ENSO Modoki and IOD that strongly depend on the ocean-atmosphere interactions. Application of the ocean-atmosphere coupled model is naturally a proven approach to overcome the shortcoming of the standalone atmospheric model and to realistically simulate the climate phenomena. For our climate predictions, we have developed the SINTEX-F1 ocean-atmosphere coupled general circulation model under the EU-Japan research collaboration. Based on this seasonal prediction system (“F1”), we have performed climate predictions at least 1 year ahead and distributed the prediction information on JAMSTEC website since 2005 (LINK). We have achieved great successes in these years and SINTEX-F1 has become one of the leading models of the world for predicting the tropical climate variations, in particular, the IOD, the ENSO and the ENSO Modoki. (publications) To improve prediction of extratropical climate, an upgraded CGCM called SINTEX-F2 has been developed; the new system is a high-resolution version with a dynamical sea-ice model (“F2”). For the tropical climate variations in the Pacific and the Indian Ocean, the SINTEX-F2 preserves the high-prediction skill, and sometimes even shows higher skill especially for strong events, as compared to the SINTEX-F1. In addition, it has turned out that the new system is more skillful in predicting the subtropics, particularly, the Indian Ocean Subtropical Dipole and the Ningaloo Nino. The SINTEX-F1/F2 seasonal prediction systems adopts a relatively simple initialization scheme based on nudging only the sea surface temperature (SST). However, it is to be expected that the system is not sufficient to capture in detail the subsurface oceanic precondition. Therefore, we have introduced a new three-dimensional variational ocean data assimilation (3DVAR) method that takes three-dimensional observed ocean temperature and salinity into account. This system (“F2-3DVAR”) has successfully improved seasonal predictions in the tropical Indian and Atlantic Ocean. “All” shows mean of all ensemble members of the three systems. The 12-member F2-3DVAR system is recently upgraded to increase the ensemble size to 108-members “108mem” SINTEX-F1 system (Luo et al. 2005) We adopt the SINTEX-F1 atmosphere-ocean coupled general circulation model, which was developed under the European Union-Japan research collaboration. The SINTEX-F1 consists of the atmospheric component ECHAM4 and the ocean component OPA8. The ECHAM4 has the horizontal resolution of T106 (~100km) with 19 vertical levels. The OPA8 has the resolution of 2 deg Mercator mesh (enhanced to 0.5 deg in the latitudinal direction near the equator) with 31 vertical levels. The atmosphere and ocean components in the model interact every 2 hours via OASIS2 coupler without any flux corrections. Since atmosphere-ocean coupled system involves the strong nonlinearity, variations in initial conditions and physical schemes lead to diverse solutions. Therefore, as is customary now, we employ many ensemble members to reduce the prediction uncertainties associated with different initial conditions and physical schemes. For creating ensemble members based on initial conditions in our prediction system, model sea surface temperature is nudged toward observed sea surface temperatures by three different negative feedback values to the surface heat flux. In addition, three different atmosphere-ocean coupling schemes are employed to represent other ensemble members. Through this processes, in total 9 ensemble members are employed for our seasonal to interannual climate predictions initiated every month. Luo, J.-J., S. Masson, S. Behera, S. Shingu, and T. Yamagata (2005), Seasonal climate predictability in a coupled OAGCM using a different approach for ensemble forecasts, J. Clim., 18, 4474-4494 SINTEX-F2 system (Doi et al. 2016) The SINTEX-F2 coupled model has been developed for better representation of several physical processes and to resolve relatively small-scale phenomena in the ocean. The atmospheric component, ECHAM5, has a horizontal resolution of 1.125 deg (T106) with 31 vertical levels. The horizontal grid used for the oceanic component, OPA9, is on the ORCA05 configuration, which has a horizontal resolution of about 0.5 deg x 0.5 deg with 31 vertical levels and without any further refinement over the tropics. The Louvain-la-Neuve Sea Ice Model, version 2 (LIM2) is embedded. As similar to the SINTEX-F1 system, the SST-nudging semicoupled initialization scheme is adopted; model SSTs are strongly nudged toward observations by applying three large negative feedback values to the surface heat flux. We used two kinds of daily SST observational dates; one is interpolated from the weekly OISSTv2 data with 1.0 deg latitude x 1.0 deg longitude global grid, and the other is the high-resolution daily NOAA OISST analysis with 0.25 deg latitude x 0.25 deg longitude global grid. In addition, considering large uncertainties in ocean vertical mixing estimations, ocean physics is perturbed in two different ways for the ocean vertical mixing induced by small vertical scale structures within and above the equatorial thermocline. Doi, T., S. K. Behera, and T. Yamagata (2016), Improved seasonal prediction using the SINTEX-F2 coupled model, J. Adv. Model. Earth Syst., 8, 1847-1867, doi:10.1002/2016MS000744. SINTEX-F2-3DVAR system (Doi et al. 2017) This system is a upgrade version of the SINTEX-F2 ystem in terms of the ocean initialization. In this system, OGCM SSTs are strongly nudged toward the observations in the coupled run continuously from January 1982, which is similar to the simple SST-nudging scheme used in the F2-system. In addition, 3DVAR correction is conducted every 1st day of each month using subsurface ocean temperature and salinity observation. The set of in situ observations consists of all types of ocean profiling instruments that provide temperature and salinity (when available) from the expandable bathythermographs (XBTs), mooring buoys, sea stations, Argo floats, etc. The details of the 3DVAR scheme used here such as formulation and specification of observation and background error covariances are shown in Storto et al. (2014) Doi, T., A. Storto, S. K. Behera, A. Navarra, and T. Yamagata (2017), Improved prediction of the Indian Ocean Dipole Mode by use of subsurface ocean observations. Journal of Climate, 30, 7953-7970. Storto, A., Masina, S. and Dobricic, S., 2014: Estimation and Impact of Non-Uniform Horizontal Correlation Length-Scales for Global Ocean Physical Analyses. Journal of Atmospheric ad Ocean Technology. 31, 2330-2349. SINTEX-F2-3DVAR 108-members ensemble system (Doi et al. 2019) The 12-member F2-3DVAR system is recently upgraded to increase the ensemble size to 108-members using the Lagged Average Forecasting (LAF) method. Based on this new system, we have conducted the prediction runs with a four-month lead-time from the eight initialized dates (1st-9th) of each month during the period from 1983 to 2019 (6-month lead time forecast is also available from some key months). Doi, T., S. K. Behera, and T. Yamagata (2019), Merits of a 108-Member Ensemble System in ENSO and IOD Predictions. J. Climate, 32, 957-972, https://doi.org/10.1175/JCLI-D-18-0193.1