Numerical Simulation And Seeding Test On The Stratiform Precipitation Around Beijing

A stratiform precipitation during 20-21 March 2008 is simulated using the mesoscale model MM5V3 coupled with CAMS explicit cloud microphysics scheme. the microphysics features, dynamics features, as well as thermal features are analyzed. Simulation results are very similar with observation. Under this circumstance, seeding tests were taken. In the tests, adding artificial ice particles at different area, different time can lead to different results. Compare time, spatial distribution of microphysical particals in seeding scheme with the biggest rainfall enhancement. Because particle numerical concentration was added, CAMS mesoscale cloud resolving model are suitable for seeding test simulation.It is shown that in this precipitation process, ice and snow particles play a very important role. Seeding tests carried out in Shanxi province had two different seeding heights. Seeding in k=12 level increased graupel and rain water quality, because the seeding height is so low that the graupel can quickly fell below 0℃level and melt into rain water. While seeding in k=13 level could bring more snow, which melt into rain water after all. Rainfall in Beijing area was less than that in Shanxi area, but the seeding results was also good. Cloud water only exited below 600hPa, and in the upper level, ice particles were very few. So when seeding was taken in k=14 level at cloud development phase, the ice particles could collide sufficient cloud water, surface precipitation increased 0.3mm.