衡阳年雷暴日数异常特征及环流背景初探

The Anomalous Characteristics of Annual Thunderstorm Days and Initially Search on Circulation Setting in Hengyang

摘要: 根据衡阳市9个气象观测站1971~2010年的逐日雷暴观测资料和美国NCEP/NCAR再分析资料，应用数理统计、Mann-Kendall、合成分析等方法分析了衡阳雷暴活动异常特征及环流背景。结果表明：1) 1971~2010年间，衡阳市年雷暴日数异常比例达42.5%，气候倾向值为−5.3 d/10a，下降趋势明显，年雷暴日数在1994年发生了气候突变。2) 雷暴异常多年副高偏弱，南支槽活跃，冷空气活动偏强，850 hPa偏东风明显强于常年；雷暴异常少年副高偏强，冷空气活动偏弱，西南季风弱于常年。3) 雷暴日数异常多年，西太平洋南北两支正距平水汽输送交汇加强后影响衡阳，孟加拉湾水汽输送强于常年；雷暴日数异常少年，来自南海、孟加拉湾的水汽输送偏弱，西太平正距平水汽输送带位置偏东。

Abstract: Based on the daily thunderstorm observational data of 9 stations from 1971 to 2010 in Hengyang and the NCEP/NCAR reanalysis data, the thunderstorm climate characteristics were analyzed by using the trend analysis, M-K test. And on this basis, the anomalous characteristics of atmospheric circulation were studied by using composite analysis. The results are as follows: 1) the rate of exceptional value of thunderstorm days is 42.5%, and the number of thunderstorm showed a down-ward trend that the possible jump points in 1994 and the speed of which is −5.3 d/10a from 1970 to 2010. 2) The intensity of the subtropical high and cold air is weaker than that in former years in the anomaly frequent year of thunderstorm day, and southern trough is weak which is stronger in the anomaly less year, the intensity of water-vapor transfer of east wind in 850 hPa is obviously stronger than that in former years in the anomaly frequent year of thunderstorm day, and the in-tensity of water-vapor transfer of south wind in 850 hPa is obviously weaker than that in former years. 3) In abnormally more thunderstorm days years, Hengyang area was influenced by two water vapors from west Pacific intersection to flow together. Meanwhile, rich moisture transported from the Bay of Bengal. But, in abnormally less thunderstorm days years, the water vapors from the South China Sea and the Bay of Bengal were weaker, and the vapor conveyor was eastward in western Pacific pleion.