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 satellite-observed rainfall and water vapor measurements from the Defense 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 (formerly Air Force Geophysics Laboratory) data assimilation system. Simulated SSM radiances are used directly in a radiance retrieval step following the conventional optimum interpolation analysis. Simulated rainfall rates in the tropics are used in a moist initilization procedure to improve the initial specification of divergence, moisture, and temperature. Results show improved analyses and forecasts of relative humidity 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.