湿位涡在云南冰雹天气分析中的应用

应用湿位涡理论, 对1997年3月云南南部频繁发生的几次冰雹天气进行了诊断分析.结果表明:在θ_e陡立密集区, 湿斜压涡度发展, 密集区内冰雹容易发生; 在降雹区低层为对流稳定的层结下 (MPV1 > 0), 有MPV2 < 0, 使湿斜压不稳定增强, 倾斜涡度得以发展; 冰雹易在MPV2负值区南侧或MPV2正值区北侧发生.

Diagnostic Analysis of Moist Potential Vorticity for Hail in Southern Yunnan

By using the concept of moist potential vorticity, the characteristics of moist potential vorticity are analyzed in several hail events over southern Yunnan on March, 1997. The results show that very stiff moist isentropes could lead to the development of moist slantwise vorticity and the initiation of hails. The lower atmosphere has convective stability ( MPV 1>0) in hail area, but the development of moist slantwise vorticity ( MPV 2<0) could be a favorable condition to the severe convection there.Moreover, it is a good environment for hail weather to develop on the north side of areas where MPV 2>0 and the south side of areas where MPV 2<0.