Study of the “1D+3D var” assimilation of the rain rate retrieved from radar reflectivity and its experiments

The one dimensional variational data assimilation system (1D var), with ability of assimilating the rain rate retrieved from radar reflectivity, is established by utilizing two linearized physical parameterizations of large-scale condensation and convection as the observational operator. A realistic water vapor profile, obtained by 1D var, is assimilated by the three dimensional data assimilation system (3D var) to produce a better quality of water vapor field for high resolution models. To preliminarily estimate the impact of the 1D+3D var assimilation of the rain rate upon short-term precipitation forecast, a case study of the severe rainfall occurred on 9 June 2010 and one month experiment (May 2011) are performed, by applying the “1D+3D var” to get the realistic water vapor profile and a better initial condition for fine resolution models.