ANALYSIS AND FORECAST IMPROVEMENTS FROM SIMULATED SATELLITE WATER-VAPOR PROFILES AND RAINFALL USING A GLOBAL DATA ASSIMILATION SYSTEM

The potential improvements of analyses and forecasts from the use of s atellite-observed rainfall and water vapor measurements from the Defen se Meteorological Satellite Program Special Sensor Microwave (SSM) T- 1 and T-2 instruments are investigated in a series of observing system simulation experiments using the Air Force Phillips Laboratory (forme rly Air Force Geophysics Laboratory) data assimilation system. Simulat ed SSM radiances are used directly in a radiance retrieval step follow ing the conventional optimum interpolation analysis. Simulated rainfal l rates in the tropics are used in a moist initilization procedure to improve the initial specification of divergence, moisture, and tempera ture. Results show improved analyses and forecasts of relative humidit y and winds compared to the control experiment in the tropics and the Southern Hemisphere. Forecast improvements are generally restricted to the first 1-3 days of the forecast.