黔西南州冰雹时空分布及春夏冰雹环境条件分析

Analysis of Temporal and Spatial Distribution Characteristics and Environmental Conditions of Hail in Southwest Guizhou

使用1961—2008年48年黔西南州8个县市气象站逐月冰雹日资料以及周边4个探空站资料,分析该州冰雹日数时空分布特征和冰雹天气发生的环境条件。结果表明,近48年来该州冰雹日数总体呈逐年减少趋势,其地区差异较大,大致是北多南少;全州一年12个月均有冰雹出现,春季冰雹日数最多,冬季次之,夏季再次之,秋季最少,4月冰雹最多,9月冰雹日数最少;该州年均冰雹日数与海拔高度呈较好的正相关,相关系数达0.934;通过对2004—2009年春夏冰雹天气发生前的CAPE值和垂直风切变分析发现,春季冰雹发生前,要求700hPa到200hPa垂直风切变达到0.002s-1以上,而对CAPE值要求不高,多在800J·kg-1以下;夏季冰雹发生前,一般要求CAPE值在700～2000J·kg-1之间,而垂直风切变大多在0.002s-1以下。

The temporal and spatial distribution characteristics and the environmental conditions when hail occurred in spring and summer are studied by using the hail daily data from 8 meteorological stations in Southwest Guizhou and the sounding data from 4 weather stations around the Southwest Guizhou from 1961 to 2008 on a monthly basis. The results show that the number of hail-day is decreasing year by year in the latest 48 years in general, and the hail occurred more frequently in the north parts than that in the south parts with a multiplicity of the different hail day number. Hail occurred in each month of the year, and the maximum nmnber of hail-day appears in spring, the second in winter, the third in summer, and the minimum in autumn. Within one year, the maximum of hail-day number appears in April and the minimum appears in September. The average annual number of hail correlates positively with the altitude, and their correlation coefficient is 0.934. According to analysis on CAPE value and the vertical wind shear before hail occurred in spring and summer from 2004 to 2009, the vertical wind shear form 700 hPa to 200 hPa must reach 0.002sI or above and CAPE value is usually below 800 J·kg^-1 before hail occurred in spring; CAPE value generally is between 700-2000 J·kg^-1 and vertical wind shear is usually below 0.002s^-1 before hail occurred in summer.