Study of the Impact of Simulated 183 GHZ Water Vapor Retrievals on Numerical Weather Prediction

摘要

Observing system simulation experiments (OSSEs) are conducted to assess the impact of the Special Sensor Microwave 183 GHz (SSM/T-2) water vapor sounder and the associated SSM/T-1 temperature sounder. Analyzed and forecast meteorological fields are improved by the addition of the SSM/T-1,2 temperature and humidity profiles. The greatest impacts occur in the Southern Hemisphere in the scenario when the civilian infrared sounder data are not available, i.e., when TOVS data are not assimilated. To calibrate the OSSE results, comparisons are made with real data observing system experiments (OSEs). These comparisons indicate that the expected impact of adding actual SSM/T-1,2 data with the stated geographic coverage and error characteristics, in the absence of TOVS data, would improve 500 mb height forecasts by approximately 12 hours in the Southern Hemisphere. However adding SSM/T-1,2 would have smaller impacts (8 h or less) in the Southern Hemisphere if added to the available TOVS data. Improvements for 200 mb wind forecasts in the tropics are: 36 hours for SSM/T-1,2 alone and 12 hours for SSM/T-1,2 and TOVS together. Little impact was seen in moisture forecasts from the addition of the SSM data, but moisture and cloud analysis were clearly improved when the SSM data was assimilated; a decrease in global root mean square error of about 5% was indicated. Keywords: Meteorological data processing; Atmospheric temperature sounding; Weather forecasting data assimilation; Meteorological satellite observations. (edc)