Assimilation of multi-time radar observations with WRF-based Ensemble Kalman Filter

Weather Doppler radar can provide high spatial and temporal resolution observations, but most observations are discarded during data assimilation. Only the radar data observed at assimilation time are used in operational prediction. In this paper, the radial velocity observation that not only at the assimilation time but also at some earlier and later time are all assimilated with Ensemble Square Root Kalman Filter (EnSRF) based on WRF model. Result shows that the new scheme produces better analysis than the traditional scheme which only uses radar observations at the assimilation time. The improvement is especially clear in the first several assimilation cycles and then decreases with following assimilation cycles generally.