Weather and climate research in Taiwan: Potential application of GPS/MET data

Meteorological research in Taiwan mainly includes the East Asian climate, t he heavy rainfall system (Mei-Yu front) and the typhoon research. In additi on to these research components, an operational center on numerical weather prediction is actively run at the Central Weather Bureau. There are strong collaborations between Taiwan and the international meteorology communitie s, The COSMIC program in Taiwan is a new Taiwan-U.S. joint program designed to launch eight low-earth-orbiting satellites in 2004 for GPS/MET sounding s. Accurate profiles of temperature and water vapor in the troposphere are ess ential for the meteorological research in Taiwan, Low-level moisture conver gence is important for the maintenance of the monsoon system. Moisture conv ergence also plays an important role in the formation and maintenance of th e heavy rainfall events in the Mei-Yu frontal system. For an accurate typho on track and intensity prediction, an accurate analysis of atmospheric flow field as well as an accurate representation of heating profile in the typh oon model is required. This means better data on the wind, the temperature and, in particular, the moisture field are needed for improved research. Wi th the potential for providing temperature and moisture information at high vertical resolution, the GPS/MET technique may make a significant contribu tion to meteorological studies in Taiwan, The GPS/MET soundings available from COSMIC provide an excellent opportunit y for meteorological research in Taiwan, Preparation work has to be done in Taiwan to take a full advantage of GPS/MET data associated with the launch ing of COSMIC. A powerful computing facility is required to meet the time c onstraint for the operational data assimilation in numerical weather predic tion (NWP). Procedures for the reception, distribution and archiving of the GPS/MET data, the procedures for quality control of the data flow, as well as the 3D and 4D-variational data assimilation systems for assimilation of GPS/MET data on both regional and global scales, need to be developed at t he Central Weather Bureau. The assimilation schemes should also incorporate the GPS/MET data with other types of remote sensing observations, as well as other conventional observations. The observational and background error covariances need to be developed, It is also important to assess the impact of GPS/MET data on the NWP and to demonstrate the added value relative to other data sets, Carefully designed assimilation experiments need to be per formed to verify the usefulness of GPS/MET soundings. It is intriguing to c onduct a field experiment during the Mei-Yu or typhoon season to validate t he GPS/MET soundings during the initial in-orbit operations of COSMIC. Fina lly, it is crucial to set up a well-equipped COSMIC data center in Taiwan.