Characteristics of atmospheric circulationforspring precipitation anomalies in Jiangxi Province and its response to ENSO Events

Based on the daily precipitation data at the 83 national automatic weather stations over Jiangxi Province in spring (March to May) from 1961 to 2018 and the diurnal reanalysis data from NCEP/NCAR, we have performed an analysis on the characteristics of atmospheric circulation for the spring precipitation anomalies in Jiangxi and its response to ENSO events. The results show that in the years with abnormally more precipitation in spring in Jiangxi, as the mid-and high-latitudes in the middle layer 500 hPa is affected by the Eurasian circulation (EU type), the blocking high near the Ural Mountains is active, and both the low trough in the Baikal Lake area and the Western Pacific subtropical high (hereinafter referred to as WPSH) are stronger than the climatic mean state, which is conductive to the writhe of cold air from the north to south and southerly warm and wet airflow in Jiangxi. In addition, the western Pacific region in east of the Philippines in the low-level 850 hPa is controlled by the anomalous anticyclone circulation, causing the enhancement of water vapor transport from the South China Sea to Jiangxi. While the atmospheric circulation characteristics in the years with abnormally less precipitation in spring in Jiangxi are opposite to those in the above years with abnormally more precipitation. Moreover, ENSO is an important forcing signal affecting the spring precipitation in Jiangxi. In the year of El Niño (La Niña) decay, the WPSH at low level 850 hPa in East Asia in spring is stronger (weaker), which is (isn' t) favorable for the transportation of water vapor from the South China Sea to Jiangxi. More (less) precipitation in Jiangxi is due to the dynamic uplift formed by convergence (divergence) in the low-level and divergence (convergence) in the upper level 200 hPa.