100 Regional downscaling of NCEP CFS seasonal forecasts by NCEP RSM

Monday, 24 January 2011
Yunfei Zhang, NOAA/NWS/EMC, Camp Springs, MD; and H. M. H. Juang

The NCEP Regional Spectral Model (RSM) is used to downscaling the NCEP Climate Forecast System (CFS) seasonal forecasts which is a part of Multi-Regional Climate Model (RCM) ensemble downscaling of global seasonal forecasts (MRED) project. The model covers the conterminous US (CONUS) at approximately 32 km resolution. The forecast time are about five months from December to the end of April of the following year for the years 1982-2008 and the initial conditions are from Nov.29-Dec. 3, Nov. 21-25, Nov. 11-15. We verified boundary condition for RSM in mean of all upper air fields and compare it for 15 members between RSM and CFS forecasts. The RSM forecasts is close to the CFS result in large scale features due to the mean bias correction scheme. But the additional regional details can be found in hydrologic variables including precipitation, surface temperature etc. It is attributed to finer terrain resolution in the regional model. We also got higher anomaly correlation score from the regional model forecasts and additional analysis results for Multi-RCMs ensemble forecasts will be reported.
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