用Zwack-Okossi方程对一次爆发性气旋的诊断分析

DIAGNOSIS OF AN EXPLOSIVE CYCLONE WITH ZWACK-OKOSSI EQUATION

利用ＥＣＭＷＦ资料作初始场，ＭＭ４模式输出的结果和Ｚｗ ａｃｋ－ Ｏｋｏｓｓｉ方程作诊断工具，对１９８１年１２月２０～２１日生成在西北太平洋的一次爆发性气旋进行了数值试验和诊断分析。得到：气旋的爆发性发展主要是由正涡度平流和非地转场激发，其中涡度平流对气旋发展贡献最大，温度平流的影响则较小，两者主要是在对流层高层起作用，而非地转场则在对流层低层起主要作用。由水汽造成的非绝热加热对本次爆发性气旋的生成影响不大，积云对流潜热的反馈作用更小。

In terms of ECMWF data as initial fields,by the MM4 model and the Zwack-Okossi equation, numerical experiment and diagnosis were carried out for an explosive cyclone occurred in the northwest Pacific on 20th to 21st Dec.1981 and the following conclusions arrived. The diabatic heating caused by moisture, especially by the cumulus convection feedback, plays a minor role in this explosive cyclogenesis. The explosive cyclogenesis is initiated by the positive vorticity advection and ageostrophic fields. The vorticity advection makes the most contribution to the development of the cyclone, while the impact of temperature advection is minor. Both mainly act on the high troposphere level, and the ageostrophic vorticity tendency principally affects the low level. In addition, The analysis of the synoptic-subsynoptic scale exchange of temperature, shows that the subsynoptic system is not in favor of the explosive cyclone, due to the weakly conversion of the synoptic scale energy to the subsynoptic scale energy in the course of the explosive cyclone development.