Evaluating the Impact of Assimilating Humidity Parameters from Scanning Instruments during Tahope for Storm-Scale Data Assimilation System-Part Ii: Performance of Synoptic Forcing Severe Weather Cases

Collocate with the Taiwan-Area Heavy rain Observation and Prediction experiment (TAHOPE) which is an international field experiment in 2020, this study plans to collect real cases during the field experiment and assimilate the humidity field information retrieved by scanning instruments (including S and Ka band radars), then examine its impact of very short-term forecasts on convective-scale weather systems. Based on the results of previous observation system simulation experiments (OSSE), the second phase of the study focuses on the severe weather system triggered by synoptic forcing (e.g. typhoon or Meiyu frontal system). The ensemble data assimilation system developed by National Central University is used with the high-resolution WRF model. In addition to assimilating radar Doppler wind and reflectivity fields, water vapor information provided and retrieved by NCAR S-PolKa radar is assimilated. With 2-3 cases during the intensive observation period in the field experiment, both horizontal and vertical structures of the convective weather system can be examined after assimilating radar observations. Moreover, very short-term forecast (0-6 h) launched by the optimal analysis fields is further investigated and evaluated.