我国南方降水集中期年际变化特征及机制分析

利用国家气象信息中心提供的我国南方1961—2012年逐日降水观测资料、NCEP/NCAR再分析资料和Hadley中心海温资料,定义了一种新的降水集中期计算方法,识别出了我国南方存在于华南和江淮两个地区的降水集中期,分析了两类集中期的年际变化特征,并且通过典型旱涝年特征分析及广义平衡反馈方法(GEFA)初步诊断了其物理机制。结果发现:华南降水集中期的年际变化主要受到衰减的混合型厄尔尼诺的调制,其主要通过激发出菲律宾地区异常反气旋而产生影响;江淮降水集中期则受到东部型厄尔尼诺衰减过程、印度洋海盆一致偏暖和北大西洋海温三极子的共同影响,它们主要通过激发出菲律宾地区异常反气旋及相联系的EAP遥相关型以及欧亚中高纬遥相关波列来影响江淮降水集中期的年际变率,对于短期气候预测具有较好的指示意义。

Interannual variation characteristics and mechanism of precipitation concentration period in southern China

Based on daily precipitation data of Southern China from 1961 to 2012 provided by National Meteorological Information Center of China, NCEP/NCAR reanalysis data and Hadley center sea surface temperature data, a new method for calculating the Precipitation Concentration Period (PCP) was defined. As a result, the PCP in South China and the Yangtze-Huaihe River region were recognized; the interannual variation and its possible mechanism was analyzed for the two PCPs, respectively, and its physical mechanism was initialy diagnosed through the analysis of typical drought-flood years'' characteristics and the Generalized Equilibrium Feedback Assessment (GEFA). The results show that the PCP in South China is mainly modulated by attenuated mixed-type El Niño, which influence the precipitation concentration in South China by stimulating the anomalous anticyclone in the vicinity of the Philippines; the PCP in the Yangtze-Huaihe River region is affected by decay process of eastern-type El Niño, the consistent warmer Indian Ocean and the North Atlantic SST Tripod, which influence the interannual variation of PCP in Yangtze-Huaihe River region by stimulating the anomalous anticyclone near the Philippines, the related EAP teleconnection pattern and the teleconnection wave train over the Eurasian middle and high latitudes. This has a good indication for short-term climate prediction.