雷州半岛夜间△θ(se)时频特性及其与雷雨天气关系分析

Time-Frequency Characteristics of△θse and Weather Relation Analysis in Leizhou Peninsula during the Night

为探究雷州半岛夜间△θ(se)时频特性及其与雷雨天气关系,以达到提高天气预报技术,利用时频分析技术和数理统计方法进行了分析和研究.结果表明:2007年雷州半岛夜间△θ(se)平均值为-2.0,最小值为-37.4,最大值为25.5,变化波动,分布形态属正偏(右偏).1、10、11、12月的夜间△θ(se)平均值为正值,2、3、4、5、6、7、8、9月的夜间△θ(se)平均值为负值.在冷空气频繁活动季节内,雷州半岛夜间△θ(se)值较大,变化波动明显,出现全年最大值和幅值变化明显的峰和谷;在高温炎热季节,变化较为平缓,只存在值较小的弱中心.在雷州半岛,冷空气活动是影响夜间△θ(se)值、振幅和波动频率的主要因素之一.雷州半岛出现雷暴、大暴雨、暴雨和大雨天气时,必须当天或近三天的夜间△θ(se)至少有一天为负值,大气不稳定是必要条件;但有时在夜间△θ(se)很小条件下,层结变性过快或不具备触发条件,也不产生雷暴、大暴雨、暴雨和大雨天气.冷空气影响后的中雨及以下的低温阴雨天气,多数为正值,对应的夜间△θ(se)值较大.

In order to improve the forecasting technique of thunderstorm and rain weather,Time-Frequency characteristics of△θse and weather relation in Leizhou Peninsula during the night were analyzed by means of numerical statistic method and time-frequency analysis,including short time discrete Fourier transform,wavelet composition,smoothing pseudorange Wigner-Ville distribution and so on.The results showed that in 2007,average value of△θse was-2.0 in Leizhou Peninsula during the night,minimum value was-37.4,maximum value was 25.5,the discrepancy was comparatively large day by day,variations fluctuation,distributional pattern classified forward bias(right avertence)distribution,decline level was not too large,distribution was not craggedness.In 1、10、11、12 months average value of△θse was positive value during the night,In 2、3、4、5、6、7、8、9 months average value of△θse was negative value.During the frequently activity seasons of cold air,variations characteristics of△θse was comparatively large in Leizhou Peninsula at night.radius-changing was large,variations fluctuation was obvious,the maximum and value variations arose obvious peak and vale all the year around,had multiple huge value center;During the blistering hot seasons of high temperature,extreme value,variations was comparative drop off,only was value lesser weak center.In Leizhou Peninsula,the cold air activity influenced value,amplitude and fluctuate frequency,it was one of principal factors.when the Leizhou Peninsula turned up thunderstorm、gully washer、rainstorm、downfall weather,at night that day and the past 3 days of△θse must be negative value,the instability atmosphere was an essential condition;but sometime△θse was very smaller at night,though not probable,caused thunderstorm、gully washer、rainstorm、downfall weather.After the cold air influencing moderate rain and subaltern precipitation weather,the value of corresponding△θse at night was comparatively large,sometimes was positive value.