A Comparison between the 3/4DVAR and Hybrid Ensemble-VAR Techniques for Radar Data Assimilation

The three/four-dimensional variational data assimilation (3/4DVAR) algorithm is compared with a hybrid ensemble-3DVAR algorithm for the assimilation of radar radial velocity observations at the convective scale in the context of the Weather Research and Forecasting (WRF) model's data assimilation (WRFDA) system. The performance of the 3/4DVAR and the Hybrid Ensemble-3DVAR algorithms is being evaluated by conducting idealized single observation experiments and real data assimilation experiments. The impact of the real radar data assimilation with the two algorithms on analyses and forecasts of the 21 July 2012 Beijing extreme rainfall event will be presented.