1 / 51

An Overview of New Developments with the NCEP Climate Forecast System

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. ACKNOWLEDGEMENTS SCIENTISTS AND STAFF OF THE :

blula
Download Presentation

An Overview of New Developments with the NCEP Climate Forecast System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. An Overview of New Developments with the NCEP Climate Forecast System SURANJANA SAHA Environmental Modeling Center NCEP/NWS/NOAA 20th 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 • Thermodynamics : 3-layer (Winton, 2000) • Dynamics : EVP Model (Hunke and Dukowicz, 1997) • The sea ice model was coupled to MOM4. • 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) Observations Model Simulation Sea ice concentration is just a little bit too high relative to the satellite observations

  12. Ocean Developmental work for the future • MOM4 • Test higher horizontal resolution everywhere for MOM4 (¼ degree globally, or ¼ degree in the tropics decreasing to ½ degree at 30N and 30S) • Increased number of vertical levels in the ocean mixed layer, from 40 to 50 • Use new, more efficient, coupler, with more frequent coupling to the ocean (than the present once a day) • 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. TEST THE CURRENT OPERATIONAL VERSION OF THE GFS (USED FOR WEATHER PREDICTION) UPGRADES • 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

  16. GFS Developmental work for the future • Test higher horizontal resolution (T126) • Test new convection scheme (RAS) • Test hybrid vertical coordinate (sigma-pressure, sigma-theta) • Test improved boundary layer physics • Test convectively forced gravity wave drag • 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 25 days WINTER 13 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. PNA NAO 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

  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. WIND 850 hPa (m/s) CLIMATOLOGY (1981-2004) SOMALI JET AREA BAY OF BENGAL ALL INDIA RAINFALL (mm/day) CLIMATOLOGY 15 DAYS (3 Pentads) 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 - CMAP DIFF 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

  33. Good variability ; Good amplitude

  34. CDAS2 Amplitude CHI 200 hPa [107 m2/s] T62 too strong T126 better

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

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

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

  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. LAYOUTSEASONAL MEANS AVERAGED OVER 24 YEARS[2007-2031] CFS T126 CFS 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

More Related