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根据地球系统模式(CESM)的千年控制模拟试验结果,以Ni?o3.4区的逐月海表温度变化为指标,辨识了212次El Ni?o事件、226次La Ni?a事件;分析了El Ni?o和La Ni?a事件发生当年及次年中国东部5—9月降水异常的空间格局;探讨了ENSO与华北、江淮、江南和华南4个区域旱涝的关系。结果表明:El Ni?o事件发生的当年5—9月,华北和华南地区降水减少2%~10%,长江中下游地区降水略有增加(0~2%);次年,江南地区转为降水增加(2%~10%),华北北部降水继续减少。在La Ni?a事件发生的当年,华北地区降水偏多(增加2%~10%);次年,江淮地区降水显著减少(2%~5%)。ENSO增强会导致降水变幅加大。在El Ni?o衰减并向La Ni?a快速发展的年份,江南地区出现洪涝灾害的概率较其他年份高1倍以上。这些认识为深入揭示气候系统内部年际变率对中国东部降水格局变化与区域旱涝的影响作用、理解2016年长江中下游发生重大洪涝灾害提供了异常天气气候背景依据。
According to the results of the millennium control simulation of the Earth System Model (CESM), 212 El Niño events and 226 La Niña events were identified based on monthly monthly sea surface temperature variations in the Niño 3.4 region The spatial pattern of precipitation anomaly from May to September in East China and the El Niño and La Niña events in the same year was discussed. The relationship between ENSO and drought and flood in 4 areas of North China, Jianghuai, Jiangnan and South China was also discussed. The results show that during the May-September period of El Niño, the precipitation in North China and South China decreased by 2% -10% and the precipitation in the middle and lower reaches of the Yangtze River slightly increased by 0-2%. In the following year, Precipitation increased (2% ~ 10%), precipitation in northern North China continued to decrease. In the year when La Ni? A occurred, precipitation in North China was more (2% -10% increase); in the following year, precipitation in Jianghuai Area decreased significantly (from 2% to 5%). ENSO increase will lead to increased precipitation amplitude. In the years when El Niño decayed and La Niña developed rapidly, the probability of flooding in the southern part of the Yangtze River was more than double that of other years. These understandings provide insight into the effects of interannual variability in the climate system on changes in precipitation pattern and drought and flood in the eastern part of China, and provide a basis for understanding abnormal weather and climate in major floods in the middle and lower reaches of the Yangtze River in 2016.