2019年6月西太平洋副热带高压脊线位置异常的机制分析  

Mechanism analysis on the abnormal ridge line position of the Western Pacific Subtropical High in June 2019

作　　者：钟中 王天驹 胡轶佳 ZHONG Zhong;WANG Tianju;HU Yijia(College of Meteorology and Oceanography,National University of Defense Technology,Nanjing 211101,China)

机构地区：[1]国防科技大学气象海洋学院,南京211101

出　　处：《气象科学》2020年第5期639-648,共10页Journal of the Meteorological Sciences

基　　金：国家自然科学基金资助项目(41430426,41675077)。

摘　　要：以2019年6月为例,采用统计和诊断分析方法研究了夏季西太平洋副热带高压脊线位置的变化特征,并分析了其位置较6月气候平均状态偏南的可能机制。结果表明:虽然2019年6月西太平洋副热带高压脊线位置总体偏南,但其经向位置异常存在纬向差异,在150°E以西区域,西太平洋副热带高压脊线平均位置偏南,而在150°~160°E区域内,脊线位置反而偏北。西太平洋副热带高压脊线位置变化与其附近异常涡度的经向分布有很好的对应关系,2019年6月西太平洋副热带高压脊线位置出现异常的原因在于其附近出现的异常扰动引起的异常涡度,而由于异常涡度分布存在纬向差异,造成西太平洋副热带高压脊线经向位置异常也出现了纬向差异。经过尺度分析简化的全型涡度方程的诊断发现,异常非绝热加热在导致2019年6月西太平洋副热带高压位置总体偏南的过程中起到了关键作用,而动力因子则对150°E以东的西太平洋副热带高压脊线向北偏移的贡献更大。Statistical method and diagnostic analysis were used to study the Western Pacific Subtropical High(WPSH)ridge position characteristics by taking June 2019 as an example,and the possible mechanism for the southerly position of the WPSH comparing with climate mean state was also investigated.Results show that though the position of WPSH ridge line is generally southerly in June 2019,there are latitudinal differences in its meridional position.Specifically,to the west of 150°E,the position of WPSH ridge line is more southerly than that of the climate mean state,but the opposite is in area between 150°-160°E.Besides,there is a good correspondence between the change of the meridional position of WPSH ridge line and the meridional distribution of the vorticity anomalies nearby.Therefore,the abnormal position of WPSH in June 2019 is attributed to the vorticity anomalies caused by the abnormal perturbations nearby.Additionally,the latitudinal distribution difference of the vorticity anomalies contributes to latitudinal difference of the abnormal position of WPSH.Furthermore,with the complete form of vorticity equation simplified by scale analysis,it is found that the abnormal diabatic heating plays an important role in making the WPSH position southernly in June 2019,while the dynamic factor contributes more to the northward movement of WPSH ridge line to the east of 150°E.

关 键 词：西太平洋副热带高压 脊线 异常涡度 全型涡度方程 

分 类 号：P434.4[天文地球—大气科学及气象学]