汕头雷暴日异常环流背景特征

Circulation background of thunderstorm day anomaly in Shantou, Guangdong province

利用1951—2010年汕头气候观象台逐日雷暴资料和NCEP/NCAR月平均再分析资料,分析了汕头雷暴日气候特征及雷暴日异常环流背景。结果表明:汕头雷暴日主要集中出现在4—9月,6月雷暴日最多。近60 a,汕头雷暴日呈显著的下降趋势,在1978年发生突变;汕头雷暴日存在多尺度振荡,主周期为25 a;500 hPa上贝加尔湖高脊、北方槽、南支槽和副热带高压的异常变化,是导致中国汕头雷暴日异常的环流系统,并且这些系统在雷暴日偏多、偏少年具有相反的变化特征。850 hPa上,在雷暴日偏多年,副热带西太平洋和孟加拉湾向中国汕头水汽输送明显增加;偏少年基本相反。

Based on the daily thunderstorm data and the monthly NCEP/NCAR reanalysis data from 1951 to 2010 in Shantou,the climate characteristics of thunderstorm day and circulation background of thunderstorm day anomaly were analyzed.The results indicate that the thunderstorm day mainly appears from April to September,especially in June.It is in a decreasing trend in recent 60 years,and there is an abrupt change in 1978.The thunderstorm day has multi-scale oscillations,and the main cycle is 25 years.The anomalies of ridge at the Baikal Lake,northern trough,southern trough and subtropical high at 500 hPa result in the abnormal circulation systems of thunderstorm day,and the changes of these systems are contrary in more and fewer years of thunderstorm days.The vapor transportation to Shantou from the subtropical western Pacific and the Bay of Bengal is strong at 850 hPa in more years of thunderstorm days,while it is contrary in fewer years of thunderstorm days.