A Sand Storm Weather Characteristic Analysis In Northern Area Of China

The genesis and development of a severe dust storm occurred in the area ofnorth-east china, north china and Mongolia during 18-22 March,2002 are analyzed,and the cause of severe dust storm is diagnosed and simulated respectively. In thefirst part, the circulation background of the Mongolia cyclone is analyzed. Then, thisprocess is simulated using MM5 non-static pattern, and the sand storm process isdiagnostic analysed by the pattern output various physical quantities from the aspectsof the helicity, upper air jet stream and so on, the results show:(1) The Mongolian cyclone is a major effective system of the sand stormweather. The cyclone occurring in the slanting pressure area is phased by thetemperature advection function primarily. The slanting function is noticeable. Thesand storm process is mainly triggered by surface gale after the cyclone cold frontand the front. On back of the ground gale formation and the cyclone development,the cold front advection as well as under the upper air jet stream momentum is themostly concerns.(2) Through the center criterion characteristic analysis, it is discovered thatthis process is following the small criterion system occurrence development, whichindicated that the small criterion system has a very vital role to strong sand stormstrengthened with the development.(3) The spiral is introduced into the sand storm research, it is discovered thatthe sand storm has the convection weather of some typical characteristics, and thelocal vertical spiral helicity has some reference value to the sand storm intensityforecast. (4) Upper air jet stream is main therm-dynamics center. The severe sand-duststorm happened at the south side of high jet exit area and downwind of vorticitycenter of 300hPa and ascending area of sub-circulation. When the variation isoccurred in the upper air jet stream, it causes the enhance of the frontal zone in thetroposphere lower part, which has provided the powerful great criterion circuiationbackground to the center criterion system occurrence, the development, and the sandstorm production.