| On August 5 ,2004(040805) , an abrupt extraordinary heavy rainfall occurred in the eastern part of Shandong Peninsula, which was a typical meso-β scale process. Observational analyses indicate this event was in close relationship with the shear line at 850hPa at the west side of west Pacific Ocean subtropical high . And the scale feature and spread process of the meso-scale convective system are gotten by analyzing time-space layout of precipitation , satellite imagery and Doppler radar data . In this study , the event has successfully simulated for 36 hours using the MM5v3.6 with two-way-interact ion and triple nested grid .The numerical simulation is made using a 38-level and MRF high resolution PBL scheme ,etc. The main results include : (1) The structural features of the meso-β scale convective system provided necessary conditions for the heavy rainfall, including instability, the intense convergence and divergence , intense vorticity .moist potential temperature center .etc .The features of the "dry-line" stored the necessary instable energy of the convective instability in Shandong Peninsula . (2) The process of the gravity wave dispersion plays an important role in trigger, transmission and enhancement of convective systems in Shandong Peninsula . (3) The simulation shows the extremely heavy rainfall and meso-β scale low vortex are well simulated .It is found that precipitation occurred earlier than meso-β scale low vortex .There is positive feedback mechanism between precipitation and meso-β scale low vortex . (4) The the dynamic influence of the complex topography in Shandong Peninsula is analyzed .The warm air current is forced to move around Shandong Peninsula and strengthened the convergence.
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