IMPACTS OF THE ENSEMBLE ASSIMILATION OF RADAR RADIAL VELOCITY ON THE INTENSITY EVOLUTION OF LANDFALLING TYPHOON VICENTE (2012)

doi:10.16032/j.issn.1004-4965.2017.03.006

Abstract：The current study explores the use of a WRF-based ensemble Kalman filter (EnKF) to continuously assimilate the high-resolution Doppler radar data near the peak stage in order to capture the detailed time evolution and the 3-D structure and dynamics of the recent Typhoon Viccntc (2012) that made landfall during 2000 UTC 23 July 2012 near the Pearl River Delta region of Guangdong Province of China.With vortex and dynamics dependent background error covariance estimated by the short-term ensemble forecasts,it is found that the WRF-EnKF can efficiently assimilate the high resolution radar radial velocity to improve the depiction of the typhoon inner-core structure of Vicente which further improves the forecasts of the track,intensity and precipitation associated with this landfalling typhoon.We further use the WRF-EnKF analysis and forecasts along with the ensembles initialized from the EnKF perturbations at different time to examine the dynamics of Vicente with respect to the number of volumes of radar observations being assimilated,different lead time before and during the landfall.We are particularly interested in the heavy rainfall associated with the landfalling Vicente which affects a large area of South China.The results show that assimilating the Doppler Radar data is a very promising way to improve the TC forecasts,which also demonstrate that doing data assimilation near the peak stage of TC also has the ability to improve the forecast.