IMPACT OF THE INITIALIZATION ON MESOSCALE MODEL PREDICTION IN SOUTH CHINA

Based on the GRAPES 3D-Var system,this paper introduced a method to calculate the temperature increment by geopotential increment using the hydrostatic equilibrium equation.The impact of initialization is studied in the South China area during a course of cold wave by assimilating the sounding data.The control and assimilation experiments of GRAPES regional mesoscale model prediction are verified with observations.Results show that the assimilation of sounding data has positive impact on GRAPES regional mesoscale model.The initial forecast sensitivities are greater than later time and vary fast,the lower levels forecast sensitivity are more complex than the upper levels,and the sounding data assimilation can do little to improve the upper levels forecast while improving the lower and middle levels forecast much better.