湖南省雷暴大风的时空分布和变化特征

Study of Temporal-Spatial Distribution and Variation Characteristics of Thunderstorm Gales in Hunan

利用1971-2010年湖南94个地面气象观测站雷暴大风观测资料,采用气候倾斜率、M-K突变检验、小波分析等统计方法分析了雷暴大风事件的变化趋势和振荡周期,并初步探讨了其成因。此外,利用2001-2010年NCEP再分析资料,选取典型站点对其不同区域动力、热力参数进行了对比统计分析,对于正确认识湖南地区雷暴大风的形成机制及其预报预测具有重要意义。结果表明:近40年来出现雷暴大风事件次数总体呈减少趋势,特别是20世纪90年代后雷暴大风次数显著下降;雷暴大风主要出现在夏季,且大部分地区雷暴大风主要集中出现在午后到傍晚时段;湖南省雷暴大风次数在1990年前后出现突变,小波分析表明存在着2~3年、3~5年、6~7年的短周期和11~12年的长周期,其中2~3年和3~5年的变化周期具有相对稳定和全域性特点。分析雷暴大风发生时表征大气热力不稳定的参数发现,不同区域的雷暴大风发生的热力不稳定条件东西向之间存在一定差异,且湘西高于湘东;动力不稳定条件南北向之间存在一定差异,湘南高于湘北;上下层水汽差存在山区高于湖区的特点。

The climate characteristics of the thunderstorm gales and its possible cause were analyzed with the data of thunderstorm gales in Hunan province from 1971 to 2010 using the climate slope,Mann-Kendall test,wavelet analysis and correlation analysis. Moreover,the paper compared and analyzed the parameters in different stations based on the NECP reanalysis data from 2001 to 2010. It＇s meaningful to understand the formation mechanism of thunderstorm gale in Hunan. The results showthat the overall amount of thunderstorm gales was decreasing continuously in Hunan over the last four decades,and the thunderstorm gales decreased significantly,especially after the 1990 s. Thunderstorm gales mainly occurred appeared primarily in the afternoon to evening in summer,and there was an abrupt change of its occurrences in 1990. It was found that there existed short oscillating periods（ 2~3,3~5 and 6~7 years） and long periods（ 11~12 years） in the occurrence of thunderstorm gales by using the wavelet analysis,besides,the short oscillating periods of 2 ~ 3,3 ~ 5 years were the main characters. Furthermore,the differences of thermal instability in different regions were analyzed,the result indicated that the west area was higher than east in Hunan. The differences of the dynamic instability suggests that the south area is higher than north in Hunan. The characteristic of upper and lower water vapor difference demonstrates that mountain area is higher than lake area.