西北太平洋SST季内振荡及其与中国东部夏季降水季内振荡的关系

利用NOAA逐日海表面温度(sea surface temperature,SST)资料、NCEP/NCAR逐日风场和比湿资料以及中国国家气象信息中心提供的逐日降水资料,研究了西北太平洋气候SST的低频周期,进一步分析了夏季西北太平洋SST季节内振荡与中国东部同期降水异常的关系。结果表明:夏季西北太平洋季节内SST异常影响中国东部同期季节内降水最显著的三个区域为:长江中游及华南沿海;江淮流域;华北大部。其影响途径主要是通过西北太平洋季节内海温与850 h Pa环流场之间相互作用,在东亚沿岸自南向北逐渐形成气旋—反气旋—气旋(反气旋—气旋—反气旋)的波列结构,引起东亚沿海局地水汽的辐合辐散,使得中国东部夏季季节内雨带从江淮流域向华北推进(从华北南撤到长江中游及华南沿海地区)。

Intraseasonal oscillation of SST over northwest Pacific and its relationship with summer intraseasonal rainfall in eastern China

Based on NOAA daily sea surface temperature(SST) data, NCEP/NCAR daily wind and specific humidity field data, and the daily rainfall data from National Meteorological Information Center of China, the low frequency cycle of climatological SST over the northwest Pacific is discussed, and the relationship between ISO(intraseasonal oscillation) SST over the northwest Pacific and ISO rainfall anomaly in eastern China in summer is also investigated.Results show that the most significant regions of ISO precipitation anomaly in eastern China affected by ISO SST anomaly over the northwest Pacific in summer are the middle reach of Yangtze River and the coastal areas of South China, the Yangtze-Huaihe regions, and most of North China.The wave train with the structure of cyclone-anticyclone-cyclone(anticyclone-cyclone-anticyclone) from south to north along East Asia coast is caused by the interaction between ISO SST over the northwest Pacific and 850 hPa circulation field, which leads to vapor convergence or divergence over East Asia coast and induces the summer ISO rain belt advancing from Yangtze-Huaihe regions to North China(retreating from North China to the middle reach of Yangtze River and the coastal areas of South China).