| A synthetic analysis of heavy rainfall event of typhoon Tailim depression inJiangxi Province during 2-4 Sep. 2005 are made with the routine observational dataand NCEP re-analysis data. It found that the heavy rainfall is resulted in thestagnated typhoon low pressure in northwestern Jiangxi, easterly airstream adequatemoisture supplies and favorable geographic conditions. The main synoptic systemsare the typhoon depression, westerlies northeast and southeast wind flow.An analysis of this event is performed by using the potential vorticity(PV),themoist PV(MPV) and the isentropic PV(IPV). The results show that PV canaccurately reflect system evolution in the baroclinic atmosphere. The correspondenceof the region where PV＞1.0(pvu) on 500hPa surface and the heavy precipitationdistrict has some reference value on the forecast of the heavy rainfall. The isentropicpotential vorticity analysis will more clearly describe the three-dimensional evolution.The matching of middle troposphere positive MPV center and lower negative MPVcenter is consistent with the Strong and persistent precipitation.The rainstorm caused by the Typhoon depression simulated with a mesoscalemodel MM5V3.7, and an analysis of the mesoscale systems separated from themodel output data shows clearly that the complex interaction of the stagnatedtyphoon depression circulation and the embedding mesoscale system created theheavy rainstorm, coupling of the high-low mesoscale system configure issignificance for the precipitation district.The terrain sensitive experiments of changing terrain height of DabieMountains shows that the physical fields will also be corresponding changesignificantly as the variation of the geographic conditions; and leading to change ofthe precipitation district and center position. The main affected areas are DabieMountains and the surrounding region; the rainstorm intensity and region are still determined by the large and mesoscale circulation system. |
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