阿克苏北部绿洲强对流暴雨与冰雹对比分析

阿克苏北部绿洲是强对流天气的高发区,虽然强对流暴雨和冰雹均为强对流天气,研究表明它们均发生在副热带锋区上,而影响系统、物理量特征均有显著不同:(1)暴雨的影响系统主要以西方路径的锋区小槽和中亚低槽为多,北支槽最少,冷空气弱且湿;冰雹以锋区小槽和北支槽为主,中亚低槽为少,冷空气相对强且干;(2)强对流暴雨的高空急流比冰雹弱,且存在一支低空偏东急流,冰雹不存在;(3)均位于湿舌区,但暴雨区湿度从低层到中层比雹区大,暴雨区850～500hPa均有明显的水汽输送,尤其低空急流输送充沛的水汽。雹区水汽输送较弱,且以天山山区向雹区的局地水汽输送为主。二者均有强的水汽辐合,暴雨区的水汽辐合比雹区强;(4)均有强的上升运动,冰雹850hPa的上升运动比暴雨强,700hPa二者相当,500hPa暴雨比冰雹略强。(5)均有强的不稳定性,暴雨的不稳定性强于冰雹。

Comparative Analysis of Severe Convective Rainstorm and Hail in North Oasis of AKESU

Severe convective weather is more frequent in north oasis of AKSU. Thought both rainstorm and hail are severe convective weather, their effect systems , features of physics quantities are remarkable different. (1) Cold air impacting on rainstorm is wet and weak, but it is strong and dry which impacts on hail; (2) The upper troposphere jet is weaker under rainstorm condition than that under hail condition, and there is an east lower troposphere jet where there is a rainstorm; (3) They are both in wet tongue, but the humidity in rainstorm area is higher than that in hail area, and there is obvious water vapor transmission from 850hPa to 500hPa, especially lower jet transports adequate water vapor to rainstorm area. There are strong moisture convergence in rainstorm and hail area, and it is stronger in rainstorm area; (4) There are strong ascending motion and severe instability, the ascending motion is stronger at 850hPa in hail area, but it is stronger at 500hPa in rainstorm area, and the instability is more severe in rainstorm area.