陕西暖季雷暴的主模态及其可能的影响机制  

The Major Mode of the Shaanxi Thunderstorm and Possible Influence Mechanism

作　　者：张宏芳 潘留杰[2] 侯建忠[2] 李明娟[2] 

机构地区：[1]陕西省气象服务中心,陕西西安710014 [2]陕西省气象台,陕西西安710014

出　　处：《地球科学进展》2013年第9期1025-1035,共11页Advances in Earth Science

基　　金：陕西省气象局预报员专项"弱天气系统强迫下黄土高原强对流云的初生及演变"(编号:2013Y-7);公益性行业(气象)科研专项"西北地区复杂地形下雷暴及短时强降水预报预警关键技术研究"(编号:GYHY201306006)资助

摘　　要：利用1960--2010年陕西76个台站雷暴、闪电观测数据和NCEP／NCAR再分析资料，基于EOF、小波等方法分析陕西暖季（5～9月）雷暴的主模态及可能的影响机制。主要结论如下：①近51年陕西雷暴日数总体呈下降趋势，月际上雷暴日数7月达到峰值，暖季雷暴日数占全年的70％以上；②雷暴日数空间型主要表现为东西向的反位相振荡（EOF1）与陕北、关中南部负异常及延安地区、陕西南部正异常（EOF2），分别解释了总方差的53．1％和13．6％；③Morlet小波分析显示EOF1，EOF2分别存在3～6年和15年左右的年代际变化周期；④EOF1空间模态的时间系数回归显示暖季大陆上气压减弱，西太平洋副热带高压584线位于30°N附近，西南暖湿气流向北输送增强，陕西西部雷暴增多；EOF2时间系数回归表明当北半球极涡偏弱，蒙古国附近气压偏强，导致北风分量增强，有利于EOF2空间型分布；⑤西太平洋副热带高压位置、强度是影响EOF1的重要因子，同样，北半球极涡可能对陕西雷暴空间模态EOF2有显著影响。Based on observational data of thunderstorm and lightening of 76 stations in Shaanxi, the National Centers for Environmental Prediction / National Centers for Atmospheric Research （NCEP/NCAR） reanalysis dataset from 1960 to 2010, the major modes of thunderstorm in warm seasons （ May to September） of Shaanxi province and mechanism of its possible influence are studied . The results show that ： （1）the thunderstorms show an obvious decreasing trend in the past 51 years, the average thunderstorm days reaching the peak in July, of which 70% oc- curred in warm season. （2）There are two dominant modes： EOF1 mode depicting a thunderstorm phase oscillation between the East and the West of Shaanxi province and EOF2 mode describing negative anomaly oscillation between the North and the middle of Shaanxi province and positive anomaly oscillation between Yan＇ an area and some areas of Southern Shaanxi province. These two modes account for 53.1% and 13.6% of total variance respectively. （3）A- nalysis with Morlet wavelet method indicates that EOF1 mode has an inter-annual changing cycle of 3 to 6 years and EOF2 has an interdecadal change cycle of about 15 years. （4）The meteorological field regression of EOF1 time coefficient shows the West Pacific subtropical high 584 line is located near 30°N ,the flowing of the southwest warm wet airflow to the north increases and the thunderstorms increase in the west of Shaanxi province; the time coefficient regression of EOF2 shows that the Northern Hemisphere polar vortex is weaker and the pressure over Mongolia area is stronger than usual result in the north wind component＇ s increasing , which contributes to the formation EOF2. （5）The important factors influencing Shaanxi thunderstorm spatial mode EOF1 include the location and the strength of Northwest Pacific subtropical high. In the same way, the Northern Hemisphere polar vortex possibly has a close connection with Shaanxi thunderstorm.

关 键 词：雷暴 主模态 西太平洋副热带高压 极涡 

分 类 号：P446[天文地球—大气科学及气象学]