Relationship between spring continuous rain over the Anhui province and different types of El Niño/La Niña decaying years

It is a great significance to improve the understanding of spring continuous rain and to prevent and reduce disasters by studying the change rule of spring continuous rain over the Anhui province in recent decades and its relationship with El Niño/La Niña events. Based on the daily rainfall and sunshine hours at 77 stations in the Anhui province and the NCEP/NCAR reanalysis dataset,the variation characteristics of spring continuous rain over the Anhui province is studied and the possible impacts from different types of El Niño/La Niña decaying different years is discussed with the methods of EOF,composition analysis,and etc. The days,the frequency,and the longest days of spring continuous rain over the Anhui province during the past 58 years show similar distribution characteristics with less in the north,more in the south,and maximum in the south of Jiangnan. The number of spring continuous rainy days has an obvious decreasing trend and decreases by 1.0 day for every 10 years on average. The spatial distribution of continuous rain days includes two patterns: consistency in all areas and contrary in the north and south. The number of spring continuous rainy days over the Anhui province is more (less) during the years with eastern pattern El Niño (La Niña) decaying,and is less during the years with central pattern El Niño/La Niña decaying. During the years with eastern pattern El Niño (La Niña) decaying,the West Pacific subtropical high (WPSH) is obviously stronger (weaker) and abnormally northward (southward),and the high pressure in the Sea of Japan is obviously stronger. In addition,there is a pattern of two ridges-one trough (one trough-one ridge) for 500 hPa geopotential height at the mid-high latitudes of Eurasia. The high ridge (low trough) over the Ural mountains and the low trough over the Lake Baykal are evident. In the meantime,the cold air from the bottom (front) of the trough (ridge) continues flowing southward,converging continuously with the southwest warm (northeast cold) air low from the Western North Pacific anomalous anticyclone (cyclone) over the Jianghui area,which leads to more (less) spring continuous rain over Anhui province. During the years with central pattern El Niño decaying,the WPSH is abnormally stronger and southwestward,and the low trough over the outer Xing' an Mountain is evident. During the years with central pattern La Niña decaying,there is anomalous cyclonic circulation over the West Pacific and the Lake Baykal,and northerly wind prevails over the Jianghuai area,which leads to less spring continuous rain over the Anhui province.