喀什地区北部短时强降水环境参数和雷达特征分析

摘要:

利用欧洲中心ERA5（0.25°×0.25°）再分析资料、探空资料、自动站小时降水资料、雷达风暴结构产品等，对2019—2023年新疆喀什地区北部短时强降水的时空分布、环流形势、环境参数、回波结构开展统计分析，并根据风暴初始位置及移动路径，将风暴划分为外部移入型、内部移动型、内部少动型。结果表明：喀什地区北部短时强降水发生在4—9月，浅山区多于平原。中亚低槽（涡）型短时强降水最多，占68.6%，西风带短波型次之。以25%百分位作为环境参数最低阈值，对流有效位能、大气可降水量、沙氏指数、K指数、抬升指数和风暴强度指数最低阈值分别为90.7 J·kg-1、16.1 mm、-1.8℃、27.0℃、-2.5℃、223.4，与中国中东部相比偏弱。内部移动型风暴次数最多，占37.9%，内部少动型次之，外部移入型最少。三类风暴的风暴顶高、垂直液态水含量、最大反射率因子、质心高度差异较为明显。

Abstract:

Using hourly precipitation data, ERA5 (0.25°×0.25°) reanalysis data, atmospheric sounding data and storm structure products, the temporal and spatial distribution, circulation situation, sounding parameters and storm structure of short-term heavy precipitation in Kashgar from 2019 to 2023 were statistically analyzed. The storms were divided into external moving storm, internal moving storm and internal less moving storm according to their initial position and moving path.The results show that the short-term heavy precipitation in Kashgar is concentrated from April to September, with more precipitation in the shallow mountainous areas than in the plains.The Central Asian trough (vortex) circulation pattern has the highest amount of short-term heavy precipitation, which accounting for 68.6%, followed by westerly shortwave pattern. Taking the 25% percentile as the minimum threshold of sounding parameters, the minimum thresholds of convective available potential energy, precipitable water, showalter index, K index, uplift index and storm intensity index are 90.7 J·kg-1, 16.1 mm, -1.8°C, 27.0°C, -2.5°C and 223.4, which are weaker than those in central and eastern China. The internal moving storms are the most, accounting for 37.9%, followed by internal less moving storms. There are obvious differences in storm top, vertical integral liquid, maximum reflectance factor and centroid height among the three types of storms.