1. An Overview of New Developments with the NCEP Climate Forecast System SURANJANA SAHA Environmental Modeling Center NCEP/NWS/NOAA 20 th Annual Climate Diagnostics and Prediction Workshop State College, PA 24 October 2005

2. ACKNOWLEDGEMENTS SCIENTISTS AND STAFF OF THE : THE GLOBAL CLIMATE AND WEATHER MODELING BRANCH ENVIRONMENTAL MODELING CENTER (EMC) AND THE CONSIDERABLE HELP AND SUPPORT OF CLIMATE PREDICTION CENTER (CPC) AND GEOPHYSICAL FLUID DYNAMICS LABORATORY (GFDL)

3. The NCEP Climate Forecast System (CFS) was made operational in August 2004 Currently, two fully-coupled nine-month forecasts are made every day The present CFS operational system at T62L64 resolution is frozen Development work is underway at EMC to improve the CFS We anticipate a new CFS implementation will take place in a few years

4. For a new CFS implementation : New upgrades to the CFS must lead to better performance Retrospective forecasts with the new CFS, covering a period of nearly 30 years, will then have to be made A global reanalysis of the atmosphere, land and ocean will have to be made, prior to that, to provide the initial conditions consistent with the new version of the CFS This is indeed an enormous challenge !!!

5. TESTING CHANGES IN THE OCEAN PART OF THE CFS

6. NEW OCEAN MODEL MOM4 (GFDL) Jiande Wang Ocean-Only Simulation Run with MOM4 1981-2004 R-2 Daily Forcing (heat flux, E-P). Same Resolution as operational MOM3, which has the following configuration : 1/3 degree at equator, gradually decreasing to 1 degree at 30N and 30S. Northern boundary is at 65N and southern boundary is at 75S 40 Vertical layers, 10 meter interval in the top 220 m Depth to 5.5 Km

7. Indonesian through flow is completely open in a larger area and the surrounding marginal seas are fully resolved as ocean (not land) points Use runoff data from NCAR (Dai and Trenberth) Use real fresh water flux, instead of “virtual salt flux”. This method gives more accuracy in the simulation of sea surface height

8. The bias everywhere is considerably less than with MOM3

9. NEW SEA ICE MODEL Xingren Wu 1.Thermodynamics : 3-layer (Winton, 2000) 2.Dynamics : EVP Model (Hunke and Dukowicz, 1997) 3.The sea ice model was coupled to MOM4. 4.The model was forced using R-2 climatology Sample results was for Year-20, March

10. Modeled sea ice thickness (Year-20, March) The simulated sea ice distribution is reasonable, but sea ice thickness may be not thick enough

11. Sea ice concentration (Year-20, March) Sea ice concentration is just a little bit too high relative to the satellite observations Model Simulation Observations

12. Ocean Developmental work for the future MOM4 1.Test higher horizontal resolution everywhere for MOM4 ( ¼ degree globally, or ¼ degree in the tropics decreasing to ½ degree at 30N and 30S) 2.Increased number of vertical levels in the ocean mixed layer, from 40 to 50 3.Use new, more efficient, coupler, with more frequent coupling to the ocean (than the present once a day) 4.Include river (fresh water) runoff from climatology or NOAH land model

13. Global Ocean Data Assimilation (GODAS) : Explicit bias correction Geostrophic balance in the assimilation Altimetry and Argo salinity added to GODAS

14. TESTING CHANGES IN ATMOSPHERIC PART OF THE CFS

15. NOAH Land Model : 4 soil levels. Improved treatment of snow and frozen soil Sea Ice Model : Prediction of ice concentration and ice fraction Sub grid scale mountain blocking Reduced vertical diffusion RRTM long wave radiation TEST THE CURRENT OPERATIONAL VERSION OF THE GFS (USED FOR WEATHER PREDICTION) UPGRADES

16. GFS Developmental work for the future 1.Test higher horizontal resolution (T126) 2.Test new convection scheme (RAS) 3.Test hybrid vertical coordinate (sigma-pressure, sigma-theta) 4.Test improved boundary layer physics 5.Test convectively forced gravity wave drag 6.Test new short wave radiation parameterization

17. TWO KINDS OF STUDIES CFS MONTHLY RETROSPECTIVE FORECASTS CFS FREE COUPLED SIMULATIONS (CMIP)

18. CFS WEEKLY AND MONTHLY FORECASTS Higher resolution, both spatial and temporal. Spatial : T126L64 GFS Atmospheric model (as in operational CFS) coupled to MOM3 Ocean Model Temporal : 4 CFS runs daily : from 0Z,6Z,12Z and 18Z Atmospheric R2 initial conditions coupled to the same Ocean GODAS initial condition Period : 2000 – 2004 (5 years) Summer : 7 May – 15 July (70 days) Winter : 7 Nov – 15 Jan (70 days) Integrations out to 65 days or more (covers the last full calendar month)

19. POSTER OF AUGUSTIN VINTZILEOS : WEDNESDAY, 9-10:30 AM THE CFS 126 : A DYNAMICAL SYSTEM FOR SUBSEASONAL FORECASTS – CHALLENGES IN PREDICTION THE MJO U200 hPa forecasts averaged 20°S-20°N and projected to the MJO EOFs obtained from R2

20. SUMMER WINTER 13 days 25 days Conclusions: Good skill and for the reasons that is shown in the poster, we expect improvements....

21. POSTER OF HUA-LU PAN : MONDAY, 9-10:30 AM CLIMATE MODEL DIAGNOSES FROM A WEATHER MODELER’S POINT OF VIEW V850 hPa forecasts and PRECIPITATION in the tropics from CFS retrospective forecasts and free coupled runs are examined

22. Conclusions: Episodic nature of easterly waves are well captured. Tropical disturbances in the T126 are better simulated

23. POSTER OF ÅKE JOHANSSON : TUESDAY, 9-10:30 AM PREDICTION SKILL OF NAO AND PNA FROM DAILY TO SEASONAL TIME SCALES Skill in predicting NAO and PNA indices (as deduced from geopotential at 500 hPa) from daily T126 and T62 retrospective forecasts for 5 winters (DJF 2000-2004) are examined, as well as the 24 winters of operational T62 CFS

24. Conclusions: There is lingering skill in both NAO and PNA out to 45 days, albeit small. PNA has higher skill than NAO in the short/medium range while NAO has higher skill than PNA in the intraseasonal time range PNA NAO

25. POSTER OF CATHERINE THIAW : MONDAY, 9-10:30 AM INDIAN SUMMER MONSOON PREDICTION IN THE NCEP CLIMATE MODEL Using retrospective forecasts from 9-13 May, the CFS prediction of the onset of the Indian summer monsoon is examined, using the wind at 850 hPa, Precipitation and SST.

26. SOMALI JET AREABAY OF BENGAL WIND 850 hPa (m/s) CLIMATOLOGY (1981-2004) 15 DAYS (3 Pentads) ALL INDIA RAINFALL (mm/day) CLIMATOLOGY Conclusions: The overall prediction of the Indian monsoon rainfall is reasonable. The onset is a little late and the rainfall is a little weak. Higher horizontal resolution and better physics may lead to improvements

27. PRECIPITATION (mm/day) JULY 2000-2004 XIE-ARKIN CMAP DIFF T126 - CMAPDIFF T62 - CMAP

28. FREE COUPLED [CMIP] RUNS ATMOSPHERIC MODEL 1. T62L64 CURRENT OPERATIONAL CFS 49 years (2002-2050) 2. T126L64 CFS OPERATIONAL VERSION 85 years (2002-2084) 3. T126L64 GFS OPERATIONAL VERSION 30 years (2002-2031) OCEAN MODEL CFS OPERATIONAL MOM3 VERSION

29. T62 very regular ; T126 better variability, weaker amplitude

30. POSTER OF CÉCILE PENLAND : MONDAY, 9-10:30 AM EL NIÑO IN THE CLIMATE FORECAST SYSTEM : T62 vs T126 Prepare CFS output as we do COADS data : project SSTs onto a 4° x 10° grid, subject to a 3-month running mean, and then project onto 20 leading EOFs

31. Conclusions: The resolution of the atmospheric component of the model matters a lot! The T126 does get the El Niño spectrum about right

32. Good variability ; Good amplitude

34. CDAS2 Amplitude CHI 200 hPa [10 7 m 2 /s] T62 too strong T126 better

35. Phase Speed CHI 200 hPa [m/s] Eastward speed : T62 too slow T126 better Westward speed : T62 too strong T126 better CDAS2 Westward propagating Easterly waves MJO

36. CDAS2 Phase Speed CHI 200 hPa [m/s] At the Equator Eastward speed : T62 too slow T126 better Westward speed : T62 too strong T126 better Semi-annual cycle in the observations not well simulated in any run

37. AnomaliesClimatology T126new has much reduced bias Illinois 2m column soil moisture from CMIP runs [ Courtesy: Fan and van den Dool, Thursday 10.30 AM ]

38. POSTER OF SUDHIR NADIGA : MONDAY, 9-10:30 AM ENSO-RELATED SALINITY VARIABILITY IN CFS Salinity simulation from a free coupled run of the T62L64 operational CFS is compared to salinity estimates from GODAS as well as synthetic salinity dataset (Maes, 2000)

39. RED = WARM EVENTS BLUE = COLD EVENTS Different water masses, caused by zonal advection Conclusions: Salinity contributes significantly to the density variability in the global oceans. The sub surface salinity shows a strong ENSO-related signal in the western equatorial Pacific Ocean

40. LAYOUT SEASONAL MEANS AVERAGED OVER 24 YEARS [2007-2031] CFS T126CFS T126 NEW CFS T62 OBS

41. PRATE [mm/day] JJA

42. PRATE [mm/day] BIAS JJA

43. PRATE [mm/day] DJF

44. PRATE [mm/day] BIAS DJF

45. PRATE [mm/day] BIAS JJA

46. PRATE [mm/day] BIAS DJF

47. PRATE [mm/day] BIAS JJA

48. PRATE [mm/day] BIAS DJF

49. PRATE [mm/day] BIAS JJA

50. PRATE [mm/day] BIAS DJF

51. CONCLUSIONS A LOT MORE WORK NEEDS TO BE DONE TO IMPROVE THE CFS. ACTIVITIES ARE IN PROGRESS IN THE FOLLOWING AREAS : INCREASED HORIZONTAL RESOLUTION OF THE ATMOSPHERIC MODEL IMPROVED PHYSICS AND NUMERICS IN THE ATMOSPHERIC MODEL NEW OCEAN MODEL WITH INCREASED HORIZONTAL AND VERTICAL RESOLUTION NEW COUPLER NEW LAND SURFACE MODEL NEW ICE MODEL ESMF COMPATIBLE GLOBAL ATMOSPHERE-LAND-OCEAN COUPLED REANALYSIS