Doppler Radar Data Assimilation and High Resolution Quantitative Precipitation Forecasting: IHOP Retrospective Studies

In this research, the IHOP retrospective studies using WRF 3D-Var Doppler radar data assimilation are conducted to evaluate its impact on high resolution quantitative precipitation forecasting (QPF). Firstly, we processed Doppler radar observations in the IHOP domain with 3-hour interval for 6 days from 10 June through 15 June 2002. The Doppler radar data from 35 radar stations went quality control and preprocessed into the WRF 3D-Var data format. Secondly, we conducted background error statistics using NMC method with the 12-km resolution WRF forecasts from 5 through 19 June 2002, and interpolated to the 3-km resolution IHOP domain for WRF 3D-Var. The background error statistics were tuned for the high-resolution data assimilation. Thirdly, numerical experiments were designed for the 6-day IHOP retrospective studies. The results from case studies using WRF 3D-Var Doppler radar data assimilation as well the 6-day statistics of the QPF skills will be presented. We will also discuss the capability and limitation of WRF 3D-Var Doppler radar data assimilation in high resolution.