Interdecaldal Variations of Drought and Flooding Disasters in China and Their Association with the East Asian Climate System
Interdecaldal Variations of Drought and Flooding Disasters in China and Their Association with the East Asian Climate System
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发表时间：
2006
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通讯作者：
Huang Rong
中科院分区：
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作者：
Huang Rong
利用观测资料，分析了中国旱涝灾害的年代际变化特征。结果表明，1976年至今，中国北部地区持续干旱，严重影响了该地区水资源和经济的可持续发展；夏季风降水明显增多，长江、淮河流域洪涝灾害频发。此外，该地区夏季风降水明显增多，洪涝灾害频发。从东亚气候系统的年代际变化特征出发，分析了中国旱涝灾害年代际变化的物理机制。分析结果表明，20世纪70年代末至今，热带中东太平洋海温升高，出现了类似于El Nio的年代际海温距平型。这不仅导致东亚和西太平洋环流异常分布的年代际变化，进而导致东亚夏季风减弱，西太平洋副高南移和西移。结果还表明，1970年代末至今，热带Walker环流的年代际变化导致北非下沉气流的加强，从而导致萨赫勒地区和北非东部的反气旋异常环流的加强。由于准定常行星波的传播，萨赫勒地区的反气旋异常环流的加强导致了从1970年代末开始在南中国上空出现的反气旋异常环流。此外，从20世纪70年代末开始，萨赫勒地区的反气旋异常环流的加强导致南中国上空出现了反气旋异常环流由于20世纪70年代末欧亚(EU)型遥相关型环流异常分布在20世纪70年代末也发生了年代际变化，1976年后在中国北部引发了反气旋环流异常分布，导致到达中国北部的南风气流减弱，长江流域和淮河流域水汽输送辐合，从而导致了20世纪70年代末中国旱涝的年代际变化。分析结果还表明，青藏高原冬春积雪的日数和厚度增加，从20世纪70年代末开始，中国西北干旱半干旱地区春季地面温度与地面气温之差变大，这有利于长江、淮河流域夏季风降水增多，中国北部夏季降水减少。
The characteristics of the interdecadal variations of drought and flooding disasters in China are analyzed by using the observed data.The results show that the persistent droughts occurred in North China from 1976 to now,which seriously affected water resources and sustainable development of economy in this region.And the summer monsoon rainfall obviously increased and flooding disasters frequently occurred in the Yangtze River valley and the Huaihe River valley in this period.Moreover,the physical mechanism of the interdecadal variations of drought and flooding disasters occurring in China is analyzed from the interdecadal variability of the East Asian climate system.The analyzed results show that the SST increased and an interdecadal SST anomaly pattern which is similar to El Nio appeared in the tropical central and eastern Pacific from the late 1970s to now.This has caused not only the interdecadal variation of circulation anomaly distributions of the East AsiaPacific(EAP) pattern teleconnection over East Asia and the the western Pacific,which has led to the weakening of the East Asian summer monsoon and the southward and westward shifts of the western Pacific subtropical high,but also the interdecaldal variability of the Walker circulation over the tropics after 1976.And the results also show that the interdecadal variability of the Walker circulation from the late 1970s to now caused the intensification of descending flow in North Africa,which led to the intensification of the anticyclonic anomaly circulation in the Sahelian region and east of North Africa.And due to the propagation of quasi-stationary planetary waves,the intensification of anticyclonic anomaly circulation over the Sahelian region caused the appearance of an anticyclonic anomaly circulation over South China from the late 1970s.Besides,since an interdecadal variation for the circulation anomaly distributions of the Eurasian (EU) pattern teleconnection over middle and high latitudes also occurred in the late 1970s,an anticyclonic circulation anomaly distribution over North China was caused after 1976.These led to the weakening of the southerly monsoon flow reaching North China and the convergence of water vapor transport in the Yangtze River valley and the Huaihe River valley,thus,the interdecadal variation of droughts and floods was caused in China in the late 1970s.The analyzed results also indicate that the days and thickness of winter and spring snow cover in the Tibetan Plateau increased,and the difference between the ground surface temperature and surface air-temperature in spring in the arid and semi-arid areas of Northwest China became large from the late 1970s.These are helpful to the increase of summer monsoon rainfall in the Yangtze River valley and the Huaihe River valley and the decrease of summer rainfall in North China.