The Impact Of Dry Intrusion On The Precipitation Of Northeast Cold Vortex

For understanding the influences of dry intrusion on the precipitation of northeast cold vortex. A typical cold vortex over northeastern China on July2011was simulated by WRF model. The results show that:Westerly trough deepened as the driving force of the northeast cold votex, The western Pacific subtropical high and East Asia blocking high have a great influence on northeast cold votex:the stability of East Asia blocking high makes the westerly trough deepened to form a cold votex.; Then the cold voltex gradually grow into maturity as the west Pacific subtropical high weakens; Finally, due to the strengthening of the western Pacific subtropical high and The healing of westerlies, the northeast cold voltex dying off.Higher values and wider coverage of500hPa positive vorticity indicates stronger intensity and wider sphere of influence of cold vortex;850hPa moisture flux divergence has a good corresponding relation with bright temperature of cloud top, they could be indicative for the precipitation of cold vortex. The precipitation mainly concentrates under the center of cold voltex rain clouds, and under the edge of it is relatively scarce.Dry intrusion has the following two aspects to affect the precipitation of cold vortex:on the one hand, it makes the rain cloud narrower and expanding to a funnel shape, as a result, precipitation mainly concentrated under the central of rain cloud. On the other hand, it increases the positive vorticity of rain cloud and strengthen the water vapor convergence uplift movement, eventually promotes the precipitation of cold vortex. The dense air from upper-level lift the warm moist air ahead of dry intrusion, it will also promotes the precipitation of cold vortex.High CAPE area has a good instruction on the precipitation of cold voltex, high value of CAPE With plenty of water vapor can result in cold voltex precipitation. High CAPE value Generally appears in the low humidity area, it will be reduced along with the precipitation process. Moreover, due to the intense radiation of sun, high CAPE area prones to appear in the low humidity area behind the dry intrusion of cold voltex. Regenerative precipitation of cold voltex is less than the last one, because of lacking of water vapor and instability is weaker.