【摘要】 利用1961年1月—2014年12月Hadley气候预测研究中心的全球海表温度(SST)资料,NECP/NCAR逐日风场、比湿等再分析资料,国家气象信息中心提供的中国753站逐日降水、160站逐月降水资料,对比分析了东部(EP)型和中部(CP)型两类El Niňo事件次年夏季长江-黄河流域降水(简记为EP型和CP型降水)低频特征,以及与之相关的低频水汽输送差异。结果表明,1)平均而言,EP型降水主要有10～20 d(最显著)以及20～30 d(次显著)低频周期;CP型降水主要有10～20 d的低频显著周期。与之相关的纬、经向水汽通量最显著低频周期也为10～20 d。2)影响EP、CP型低频降水共同的低频水汽环流系统主要有:菲律宾群岛附近的异常反气旋式水汽环流和渤海湾附近(日本东南侧)的异常气旋式(反气旋式)水汽环流。另外,影响EP(CP)型低频降水的还有来自巴尔喀什湖东北部异常气旋式水汽环流(孟加拉湾、苏门答腊岛以西的异常气旋式水汽环流对和贝加尔湖西、东两侧的异常气旋式、反气旋式环流)。3)EP型降水暖湿水汽主要源自南海,冷湿水汽主要源自西北太平洋,冷空气来自巴尔喀什湖东北部和贝加尔湖西北侧。CP型降水暖湿水汽少量来自阿拉伯海和印度洋,大量来自热带西太平洋,冷空气主要来自贝加尔湖西北侧。更多还原

【Abstract】 Using the global monthly sea surface temperature( SST) from the Hadley Climate Prediction and Research Center,NCEP/NCAR daily w ind field and specific humidity,and 753-station daily precipitation and 160-station monthly precipitation data from the National M eteorological Information Center,the differences in the low-frequency characteristics of the precipitation and its related moisture transport paths in the Yangtze River-Yellow River Basin in the follow ing summer of eastern Pacific( EP) and central Pacific( CP) type El Niňo events are analyzed.For the sake of clarity,precipitation is distinguished as EP-type and CP-type precipitation. The results reveal the follow ing: 1) For EP-and CP-type precipitation,the most significant frequency oscillation period is 10—20 d,follow ed by 20—30 d,w hile the w eakest is 30—60 d.For the typical 7-year average time series of precipitation,the most significant is 10—20 d,follow ed by the 20—30 d low-frequency oscillation period for EP-type precipitation,yet for CP precipitation there is only 10—20 d significant low-frequency oscillation period.2) The zonal and meridional vapor flux are of significant 10—20 d,20—30 d and 30—60 d low-frequency oscillation periods,among w hich 10—20 d is the most significant,and this characteristic is more obvious especially for meridional vapor flux.When comparing the tw o types of events,the significance of the 10—20 d and 20—30 d low frequency cycles are equivalent for both the EP-and the CP-type zonal w ater vapor fluxes,and the 30—60 d cycle of EPtype zonal w ater vapor flux is slightly stronger than that of the CP-type. In the meridional w ater vapor flux,the EP-type is slightly w eaker( stronger) than the CP-type in the low frequency period of 20—30 d( 30—60 d).3)The main low-frequency w ater vapor circulation systems w hich affect the low-frequency heavy precipitation over the Yangtze River-Yellow River Basin in the follow ing summer betw een the EP-and CP-type El Niňo events are different.The main and most common 10—20 d vapor circulation systems affecting both the EP-and CP-type low-frequency precipitation include the anomalous anticyclonic moisture circulation around the Philippines,the anomalous cyclonic( anticyclonic) moisture circulation to the Bohai Gulf( southeastern Sea of Japan). In addition,the10—20 d vapor circulation systems w hich affect the EP( CP) type low-frequency precipitation also include the anomalous cyclonic moisture circulation to the northeast of the Balkhash( the anomalous cyclonic moisture circulation pairs around the Bay of Bengal and to the w est of Sumatra,and the anomalous cyclonic and anticyclonic moisture circulation to the w estern and eastern sides of Lake Baikal,respectively).4) The w ater vapor sources of low-frequency strong precipitation for both the EP-and CP-type heavy precipitation in the summer of the follow ing year are also different over the Yangtze River-Yellow River Basin. Warm vapor originates from the South China Sea,cold vapor from the northw est Pacific,and cold air from the northeast of Balkhash and northeast of Lake Baikal for the EP-type precipitation.A small amount of w arm vapor originates from the Arabian Sea and Indian Ocean,w hile a large amount of w arm vapor originates from the tropical Western Pacific,and cold air from the northeast to Lake Baikal for CP-type precipitation.更多还原