The Diagnosis And Numerical Simulation Of A Rainstorm Event Related To Northeast Cold Vortex

The cold vortex is one of the main weather systems over northeastern China. It is another cut-in and key problem of the heavy rainfall over Northeastern China to probe into the mechanism of the cold vortex rainstorm. The settlements of these problems are very useful to enhance the forecasting level of heavy rainfall especially these related to cold vortex over Northeastern China.This paper conclude four parts: first part gives the review of the heavy rainfall, especially the cold vortex rainfall during recent years and point out the urgent issues to be solved. Basing on the issues mentioned above, the second part shows a circumfluence character and thermo-dynamic structure study on one case of a heavy rainfall of cold vortex system. The discussion on the large-scale background; high-low altitude distribution and possible mechanism are concluded. The third part analyzes the development of meso-scale convective systems (MCSs) under the cold vortex system. By using encrypt ground-observing data, radar and satellite data, the dynamic and thermo conditions of the MCS are discussed. The forth part gives the GRAPES model and MM5 model results, which bring further studies on the structure of the cold vortex system.Three main weather systems affecting the rainfall over Northeastern China, cyclone, typhoon and cold vortex, are firstly discussed and the progresses on the cold vortex in the past decades are especially stated. Then circumfluous features and thermal, dynamical structure of the cold vortex system are discussed, and find that there was mutual configuration of upper-level jet stream, low -level jet stream, cold vortex, ground cyclone and front existing in this heave precipitation process. In The cold vortex precipitation process, two jet streams maintained in the upper troposphere. There was a cold-dry air intrusion to the middle-low layer of troposphere before the precipitation prophase, the fact implied that it is one of the trigger mechanisms when cold-dry air invaded lower troposphere and caused instability energy releasing.In addition, the physical conditions and thermo-dynamic structure of the MCS under the background of cold vortex are analyzed using encrypt observational data. It is found that the heavy precipitation process could be well supervised by combining the satellite and radar data. The radar echo data shows that the distribution of the radar over Northeastern China can well reflect the movement and the intensifying of the cold vortex. Finally, the numerical simulation results show that the rainfall and circulation field simulation results of GRAPES model are good, but the simulated rainfall intensity is some sort of low. The results of MM5 model simulation indicate that the rain belt is west-leaning, while the heavy rainfall area center and whole rainfall belt are reflecting well. The potential heights, as well as high temperature field of Northeast Cold Vortex simulation of both models are satisfying; the results of two models are valuable. The results of MM5 model simulation show that the cold-dry intrusion from the north of cold vortex is obvious during the development state. The cold-dry air intrusion played an important role the development of the cold vortex.