Comparison between anomalies of summer rainfall in China in decaying years during super El Nio events of 2015/2016 and 1997/1998
GUO Dong;WANG Linwei;LI Zhenkun;SU Yuchen;QIN Hao;HUANG Ying;Key Laboratory of Meteorological Disaster,Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(IL-CEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD) ,Nanjing University of Information Science & Technology;Shanghai Public Meteorological Service Center;Shanghai Climate Center;
The El Nio Southern Oscillation is the most significant interannual scale signal of global tropical air sea systems. It can affect the East Asian monsoon system through the teleconnection form of air-sea interaction,follow-ing w hich it has an impact on climate in China. Therefore,El Nio is one of the most important predictors of short-term climate in China. El Nio events typically begin in the spring and summer,mature in the autumn and w inter,and subside in the spring and summer of the follow ing year. Considering the hysteretic response of the at-mosphere to the ocean,El Nio can have an influence on the atmospheric circulation over East Asia,and even the precipitation in China in decaying years of El Nio.Therefore,the anomalies of summer rainfall in China and atmospheric circulation over East Asia in the decaying years of tw o super El Nino events( 2015/2016 and 1997/1998) w ere compared,in order to improve the understanding of the relationship betw een El Nio events and climate anomalies in China,as w ell as to provide a reference for short-term climate prediction. Specifically speaking,the percentage of precipitation anomaly in China,w ater vapor flux anomaly,anomaly of w ater vapor flux divergence,geopotential height anomaly,w estern end of the ridge and position of the ridge of the subtropical high and sea surface temperature anomaly in the decaying years of tw o super El Nino events w ere analyzed,by means of the monthly mean precipitation data of 160 meteorological observation stations in China,along w ith the circulation index,Indian Ocean Basin-w ide Warming index from the National Climate Center of China M eteorological Administration,monthly mean geopotential height,w ind,specific humidity and surface pressure from the American National Centers for Environmental Prediction,and the Optimum Interpolation Sea Surface Temperature version 2 data from the American National Oceanic and Atmospheric Administration.The results are as follow s. Summer rainfall frequently occurs on a large scaleand flood disaster is serious in2016 and 2008. How ever,summer rainfall anomalies in the tw o years also have different characteristics. The area of summer precipitation positive anomaly in 2016 is more concentrated than that in 1998,but the intensity of precipitation in 2016 is low er than that in 1998. In June and July 2016,the positive anomalous precipitation is maintained in the area to the north of the Yangtze River. By August,the positive anomalous precipitation area is significantly reduced. There is only a small range of rainfall in southern China,w hich is mainly caused by typhoons.Therefore,the seasonal moving features of the rain band are not significant,w hile the area of the rainfall positive anomaly gradually moves from south to north during the summer of 1998,w hich is consistent w ith the traditional process of the precipitation of the monsoon. The difference of summer rainfall in 2016 and 2008 in China is closely related to the difference of the anomaly of w ater vapor flux divergence caused by the anomaly of atmospheric circulation. The Pacific Subtropical High in summer 1998 is more robust and located more to the w est than that of summer 2016,and the ridge of the Pacific Subtropical High in summer 1998 is more to the south than that of2016. M oreover,the Pacific Subtropical Highin June and July is located more to the southw est in 1998 than 2016,w hile the Pacific Subtropical High in August is more to the w est in 2016 than 1998,and more to the north than usual. These differences of the Pacific Subtropical High can partially explain the differences betw een the 2016 and2008 summer rainfall in China. Further more,one possible reason for the difference of the Pacific Sub tropical High in June and July in 1998 and 2016 is that the Western Equatorial Pacific sea surface temperature in 1997/1998 is colder than that in 2015/2016. The difference of the North w estern Equatorial Pacific sea surface temperature may also attribute to the difference of the Subtropical High in August of 1998 and 2016.
【Fund】： 国家自然科学基金资助项目(41641042;41675039;41305039;41375047;41305079;91537213);; 江苏高校优势学科建设工程项目(PAPD)
【CateGory Index】： P426.6;P732
【CateGory Index】： P426.6;P732