Unusual Rainfall in Southern China in Decaying August during Extreme El Nino 2015/16: Role of the Western Indian Ocean and North Tropical Atlantic SST
Unusual Rainfall in Southern China in Decaying August during Extreme El Nino 2015/16: Role of the Western Indian Ocean and North Tropical Atlantic SST
复制标题
2015/16极端厄尔尼诺现象期间中国南方8月异常降雨：西印度洋和北热带大西洋海温的作用
DOI：
10.1175/jcli-d-17-0827.1
复制
发表时间：
2018-09-01
影响因子：
4.9
通讯作者：
Chen, Sheng
中科院分区：
文献类型：
--
作者：
Chen, Jiepeng;Wang, Xin;Chen, Sheng
以往的研究表明，异常的西北太平洋反气旋（WNPAC）一般可以从厄尔尼诺成熟冬季持续到随后的夏季，并对中国南方（包括长江流域和华南）的降水产生显著影响。自20世纪70年代末以来，已经记录了三次极端厄尔尼诺事件：1982/83，1997/98和2015/16。2015/16年极端厄尔尼诺事件与前两次极端厄尔尼诺事件之间，华南降水和相应大气环流的变化在衰减的8月份形成了鲜明的对比。1983年8月和1998年8月极端厄尔尼诺事件导致的热带印度洋海盆增暖导致了长江中上游地区降水的增加和华南地区降水的减少，这与前人的研究结果一致。然而，2016年8月，一个异常的西北太平洋气旋出现，随后导致华南地区出现正降水异常，长江至黄河中下游地区出现负降水异常。在不考虑长期全球变暖趋势影响的情况下，2016年8月西印度洋海温负距平和北热带大西洋降温导致西北太平洋气旋异常，华南和长江流域降水异常型与之相反。利用CAM 5模式进行数值试验，证实西印度洋海温偏冷对西北太平洋气旋和华南降水异常的贡献大于北热带大西洋海温偏冷。
Previous research has suggested that the anomalous western North Pacific anticyclone (WNPAC) can generally persist from an El Nino mature winter to the subsequent summer, influencing southern China precipitation significantly, where southern China includes the Yangtze River valley and South China. Since the late 1970s, three extreme El Nino events have been recorded: 1982/83, 1997/98, and 2015/16. There was a sharp contrast in the change in southern China rainfall and corresponding atmospheric circulations in the decaying August between the 2015/16 extreme El Nino event and the earlier two extreme El Nino events. Enhanced rainfall in the middle and upper reaches of the Yangtze River and suppressed rainfall over South China resulted from basinwide warming in the tropical Indian Ocean induced by the extreme El Nino in August 1983 and 1998, which was consistent with previous studies. However, an anomalous western North Pacific cyclone emerged in August 2016 and then caused positive rainfall anomalies over South China and negative rainfall anomalies from the Yangtze River to the middle and lower reaches of the Yellow River. Without considering the effect of the long-term global warming trend, in August 2016 the negative SST anomalies over the western Indian Ocean and cooling in the north tropical Atlantic contributed to the anomalous western North Pacific cyclone and a rainfall anomaly pattern with opposite anomalies in South China and the Yangtze River region. Numerical experiments with the CAM5 model are conducted to confirm that cooler SST in the western Indian Ocean contributed more than cooler SST in the north tropical Atlantic to the anomalous western North Pacific cyclone and anomalous South China rainfall.