华南冬季准静止锋年际变异特征及其对东亚气候的影响

INTERANNUAL VARIATION OF WINTER QUASI-STATIONARY FRONT OVER SOUTH CHINA AND ITS IMPACT ON EAST ASIAN CLIMATE

关键词:  气候准静止锋  年际变异  冬季  东亚气候  海温

Key words:  climate quasi-stationary front  interannual variation  winter  East Asian climate  sea surface temperature

摘要:

基于JRA55再分析资料、观测的降水量和海表温度等数据，利用统计诊断方法分析了华南冬季气候准静止锋的主要变异特征，并探讨了其与环流、海温及东亚气候的联系。华南冬季气候准静止锋的主要变异模态表现为强度变异模态和经向位置变异模态，它们以年际变化为主。类东部型ENSO海温异常及热带中西印度洋海温异常对华南准静止锋强度的年际变异有显著影响；而类中部型ENSO海温异常型显著影响着华南气候准静止锋的南北位置。华南冬季准静止锋的强度变异对东亚副热带地区的降水、以及我国东部内陆地区的近地面气温有显著影响；华南冬季准静止锋南北位置变异则显著影响我国江淮流域降水、以及我国华南至东南沿海一带的近地面气温。华南冬季准静止锋的强度变异模态对东亚的降水和近地面气温的影响范围较位置变异模态都要大。

Abstract:

Based on the JRA55 reanalysis data, observed precipitation and sea surface temperature (SST) data, this study has investigated the spatio-temporal variation features of the winter quasi-stationary front (WQF) over South China, and explored their linkage with circulation, SST and East Asian climate by conducting statistical diagnosis. The first two leading modes of WQF over South China are associated with intensity variation and meridional position variation, respectively, and mainly present interannual variation. The intensity variation mode (IVM) is mainly regulated by the collaboration of the eastern type of ENSO-like SST anomalies and the SST anomalies on the central-western tropical Indian Ocean. The meridional position variation mode (MPVM) is modulated by the central type of ENSO-like SST anomalies. The IVM may lead to abnormal precipitation over subtropical East Asia and abnormal surface air temperature over the inland area of eastern China while the MPVM induces abnormal precipitation over the Yangtze-Huaihe valley and abnormal surface air temperature over South China and the southeast coast of China. Compared with the MPVM, the IVM has greater influence on the precipitation and surface air temperature over East Asia.