Validation of Global Soil Moisture Products from SMAP Radiometer Observations and their Application in NCEP Global Forecast System

With the launch of NASA Soil Moisture Active/Passive mission, new global soil moisture data products become available for applications in numerical weather predictions (NWP). Although the latency of NASA official soil moisture data products may not meet the latency requirement of operational NWP models at NOAA NCEP, a good portion of the level 1 SMAP radiometer brightness temperature (TB) observations acquired in the past up to 6 hours may arrive before an operational NWP model run. Since a direct TB assimilation capability of the NCEP NWP models has not been obtained or tested yet, a soil moisture data assimilation algorithm has been implemented for NCEP Global Forecast System (GFS) and may be tested with the soil moisture retrievals from the SMAP TB observations. The SMAP soil moisture retrievals can be obtained from NESDIS Soil Moisture Operational Product System (SMOPS) a few minutes after SMAP TB data arrive at NOAA. This study compares the SMOPS retrieved SMAP soil moisture data products with the NASA official soil moisture data products and corresponding in situ soil moisture measurements, and then attempts to assimilate both SMAP soil moisture data products into NCEP GFS through the implemented data assimilation algorithm. The impacts of the soil moisture data products on GFS forecasts will be assessed. Preliminary validation results of the global soil moisture data products and the GFS impact assessment through the verification of GFS forecasts against surface and sounding observations will be presented and discussed.