In the past decades, with the increasing frequency of extreme weather and climate events, the world has suffered huge losses. Based on NCEP/NCAR reanalysis data and China regional precipitation data provided by China Meteorological Administration, the extreme precipitation events in eastern China are defined by relative threshold method, and the temporal and spatial characteristics of summer extreme precipitation in eastern China from 1961 to 2016 are analyzed by empirical orthogonal function (EOF), and the reverse distribution of extreme precipitation in the middle and lower reaches of the Yangtze River and south China by Indian Ocean warm pool is revealed influence. The results show that the total amount and frequency of extreme precipitation in summer are concentrated in the Yangtze River Basin and south China. EOF1 decomposition of extreme precipitation reflects the interannual oscillation characteristics of reverse spatial distribution in the Yangtze River Basin and south China. The time series corresponding to EOF1 has significant interannual characteristics. The Pacific-Japan (PJ) teleconnection pattern is a circulation system that significantly affects the spatial-temporal pattern of extreme precipitation in southern China. When the PJ pattern is in the positive phase, the anticyclone controls the south China region, and restrains the convective activity, which results in the decrease of extreme precipitation. The anomalous southwest wind to the south of 30˚N and the anomalous northerly wind to the north of 30˚N converge in the middle and lower reaches of the Yangtze River. Combining with the sufficient water vapor carried by the anomalous southwest airflow at the edge of anticyclone, it is more conducive to the formation of extreme precipitation. The east propagating Kelvin wave in the warm pool of the Indian Ocean is an important reason for the formation of the PJ pattern and finally the formation of extreme precipi
<div> <p>Using a Lagrangian trajectory model, contributions of moisture from the Indian Ocean (IO), South China Sea (SCS), adjacent land region (LD) and Pacific Ocean (PO) to the interannual summer precipitation variations in Southwest China (SWC) are investigated. Results show that on average, IO, SCS, LD, and PO contribute 46.8%, 25.3%, 21.8% and 2.3% of total moisture release in SWC in summer. In the above-normal precipitation summers, the moisture from IO and LD is increased by 48.2% and 28.8%, whereas that from SCS is decreased by 37.2%. In the below-normal precipitation summers, the moisture from IO and LD is decreased by 34.6% and 25.2%, while that from SCS is increased by 23.7%. In addition, the moisture anomalies from the four source regions can explain 85% of the total variances of the SWC summer precipitation.</p> <p>The variations in the moisture from IO, SCS, and LD to SWC are not independent to one another and strongly influenced by the large-scale atmospheric circulation anomalies in the lower troposphere analogous to the Pacific-Japan (PJ) pattern and further studies showed that the PJ pattern was stimulated by the SST anomaly in the equatorial Atlantic. The anomalous warming in the tropical Atlantic that can modify the Walker circulation and introduce an anomalous descending over the central Pacific, thus inducing the anomalous anticyclone in the western North Pacific as the classical Matsuno-Gill response. The resultant suppressed precipitation in the western North Pacific excites the PJ pattern. The observed impacts of the tropical Atlantic SSTs on the atmospheric circulation can be well reproduced in an atmospheric general circulation model and the ability of the CMIP5 and CMIP6 models to reappear this relationship is verified, which will help the models to improve the simulation performance of summer large-scale circulation anomalies and precipitation in East Asia.</p> </div>
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