THE BEIJING AREA MESOSCALE NWP SYSTEM AND ITS APPLICATION

Significant progress has been made on the development of mesoscale numerical weather prediction (NWP)system for Beijing area,as a joint project of the National Meteorological Center(NMC)and the Beijing Meteorological Bureau(BMB).On the basis of the non-hydrostatic mesoscale model PSU/NCAR MM5,a mesoscale NWP system for Beijing area(BJ-MM5V.1)has been developed on the computer IBM/SP2 MPP with 24 nodes at NMC.As a two-way nested grid model two grids are chosen with 45 and 15km grid length respectively,and 23 levels in the vertical.It takes 2 hours and 20 minutes to make a 36h forecast,which satisfies the time requirement for the operational use.In addition to the routine data received from GTS at NMC,the enhanced observations over Beijing region are used for the objective analyses.This system was put into semi-operational use during the summer of 1997 to test its performance.The forecast products,hourly rainfalls and all of the meteorological elements needed,are provided to the forecasters at BMB for use.It is identified from the test results that the system is robust and has pretty good ability to forecast the spatial and temporal distribution of the precipitation for the local heavy rainfalls.