Prediction and Error Analysis of a Heavy Rain Process with GRAPES_MESO Model

Using southwest vortxt experiment data,routine radiosonde and surface data,automatic meteorological observing station data and so on,the prediction performance has been analysed with Grapes_meso model run by National Numerical Prediction Center for a heavy rain process happening over Sichuan province from 14 to 19 July.2010.The results show that the precipitation prediction can reflect real precipitation on some certainty.Based on the model error analysis,the article points out the reasons leading to the error of precipitation prediction that may be the lasting lower height fields of prediction,the stronger low systems and the weaker high system,which made the convergence low system maintain over Sichuan.The stronger landing typhoon prediction,whose periphery air linked to the periphery air of subtropical high leaded to southwest low air prediction stronger.Additionally,vapor prediction was more in western and less in eastern over the basin,cold air intensity prediction was weaker,and warm and wet air were active,the jet band moved faster,so,the place of convergence field was more in northern and eastern,which leaded bigger precipitation error with the model integral time increasing,the rainfall was weaken in the northeast,the precipitation areas were more in northern and eastern.The radiodsonde analysis also indicated the temperature deviation in the basin was bigger,which maybe caused by interpolation error under complex terrain condition and observing error.Due to terrain effect on the stations in the basin,the wind analysis occurred greater uncertainty.The results also revealed the basic error characteristics,such as higher negative error possibility of height and surface pressure,positive error possibility of temperature and so on.The error origin will need to be analysed further by the means of numerical experiments or dynamics diagnose.