摘要:主要利用1961~2014年中国东部地区438个台站的逐日降水资料和NCEP/NCAR的再分析资料，从大气内部动力角度对夏季不同极端降水情况下的环境场进行分析，结果表明：对长江中下游地区而言，在极端降水频次偏多年时，850 hPa风场及整层水汽输送距平场均表明东亚夏季风偏弱，有利于更多的水汽输送到长江中下游地区，500 hPa鄂霍次克海阻塞高压持续日数偏多，有利于冷空气南下，200 hPa东亚副热带急流偏南，且30°N以南偏西风异常有利于辐散，而在斜压波包从西北东南向传播为极端降水事件分发生集聚了能量；对华北地区极端降水频次偏多年而言，850 hPa风场及整层的水汽输送距平场均表明东亚夏季风偏强，有利于更多的水汽输送到华北地区，500 hPa高度距平场日本海正距平，贝加尔湖蒙古地区为负距平，华北地区东高西低，200 hPa东亚副热带急流偏北，从而导致我国华北地区极端降水频次偏多，能量传播也为西北东南向。这些结果表明极端降水的变化，与大气内部的动力作用和能量的传播有密切的关系。
关键词:极端降水事件/
环流异常/
波作用通量
Abstract:Anomalous circulations associated with various extreme precipitation events in summer are investigated from the perspective of atmosphere dynamics using daily precipitation data collected at 438 stations from 1961 to 2014 in eastern China and the NCEP/NCAR reanalysis data. The results demonstrate that in the middle and lower reaches of the Yangtze River, increases in the frequency of extreme precipitation always correspond to weaker than normal East Asian summer monsoon, which is reflected in abnormal 850-hPa wind field and water vapor flux that are favorable for more water vapor transport to the middle and lower reaches of Yangtze River. At 500 hPa, a blocking high persists over the Okhotsk Sea, which is conductive to the cold air moving southward. The East Asian subtropical westerly jet anomalously moves southward at 200 hPa, while the westerly wind anomalies to the south of 30°N promotes divergence development, and the wave activity fluxes are favorable for generating and maintaining wave perturbations in this region. In North China, corresponding to increases in the frequency of extreme precipitation, anomalies of 850-hPa wind field and water vapor flux indicate that the East Asian summer monsoon is stronger than normal, which strengths the water vapor transport to North China. The positive anomaly is located over the Sea of Japan and the negative anomalies are located over Mongolia, Baikal and their vicinity at 500 hPa. East Asian subtropical westerly jet abnormally shifts northward at 200 hPa, while the wave activity fluxes are also favorable for generating and maintaining wave perturbations in this region. All the above results suggest that the occurrence of extreme summer precipitation in East China is closely associated with atmospheric dynamics and energy transmission.
Key words:Extreme precipitation events/
Anomalous circulation/
Wave activity flux
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