| 南海、孟加拉湾不对称环流变化对2009年西南特大秋旱的影响 |
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| 引用本文： | 艾永智,金少华,郑建萌,周泓.南海、孟加拉湾不对称环流变化对2009年西南特大秋旱的影响[J].热带气象学报,2012,28(4):594-602. |
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| 作者姓名： | 艾永智 金少华 郑建萌 周泓 |
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| 作者单位： | 1. 玉溪市气象局,云南玉溪,653100
2. 云南省气候中心,云南昆明,650034 |
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| 摘 要： | 利用NCEP再分析资料及我国160站降水资料,分析了2009年秋季东亚中、低纬环流特征和水汽输送特征及其对西南干旱的影响。同时讨论了秋季不同ENSO状态下东亚地区水汽输送差异,并与2009年进行比较。结果表明:孟加拉湾(简称孟湾)和南海之间环流形势在2009年秋季发生不对称变化,造成两地上空气压梯度减小,孟湾和南海上空分别出现一个反气旋式和气旋式距平环流中心,我国西南至中南半岛处于两距平环流中心之间偏北距平风控制之下,使得进入我国的西南气流异常减弱。水汽输送随之出现变化,南海南部季风低压水汽环流圈异常偏强,孟湾和南海水汽主体经中南半岛重回南海而未进入我国,最终造成我国西南降水异常偏少,出现干旱。这段时间内,西南地区上空出现异常下沉运动,对流活动受到抑制,加剧了干旱程度。在El Ni o年,我国西南及江南地区秋季水汽通量比La Ni a年明显增大,西北及华北则减少。2009年秋季我国的降水分布及南海一带水汽输送特征与普通El Ni o年特征不符,甚至出现相反状态,经对2009年秋季东亚El Ni o影响特征作简单模拟还原和分析,认为上述差异可能与El Ni o反气旋环流影响位置偏北有关。
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| 关 键 词： | 气候学 西南干旱 环流变化 水汽输送 南海 孟加拉湾 ENSO |
ASYMMETRIC VARIATION OF THE CIRCULATION OVER THE SOUTH CHINA SEA AND THE BAY OF BENGAL AND ITS IMPACTS ON THE SERIOUS DROUGHT IN SOUTHWEST CHINA IN AUTUMN OF 2009 |
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| AI Yong-zhi
,
JIN Shao-hua
,
ZHENG Jian-meng
,
ZHOU Hong.ASYMMETRIC VARIATION OF THE CIRCULATION OVER THE SOUTH CHINA SEA AND THE BAY OF BENGAL AND ITS IMPACTS ON THE SERIOUS DROUGHT IN SOUTHWEST CHINA IN AUTUMN OF 2009[J].Journal of Tropical Meteorology,2012,28(4):594-602. |
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| Authors: | AI Yong-zhi JIN Shao-hua ZHENG Jian-meng ZHOU Hong |
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| Institution: | 1(1.Yuxi Meteorological Bureau,Yuxi 653100,China;2.Climate Center of Yunnan Province,Kunming 650034,China) |
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| Abstract: | Based on reanalysis data of NCEP and the monthly precipitation data of 160 stations in China during 1971～2009,the characteristics of circulation and water vapor transport at the middle and low latitudes of East Asia in the autumn of 2009,as well as the impact of circulation and water vapor transport features on a drought of the southwest China,were analyzed.Furthermore,the differences of the water vapor transport in autumn over East Asia in different ENSO state were discussed,and the situation in 2009 was compared.The result shows that the circulation situation between the Bay of Bengal and the South China Sea showed asymmetric variation in the autumn of 2009,causing pressure gradients to decrease between the two regions,and anomalously anti-cyclonic circulation and cyclonic circulation appeared over the Bay of Bengal and the South China Sea separately.The southwest China and the Indo-China Peninsula were lying between two centers of anomalous circulation,causing the southwest air current to move into China to weaken anomalouslly and changing water vapor transport accordingly.The water vapor circulation cell of a monsoon depression in the south of the South China Sea was anomalously strong,and the water vapor from the Bay of Bengal and the South China Sea returned to the South China Sea through the Indo-China Peninsula,without re-entry into China,decreasing the precipitation in the southwest China and resulting in the drought eventually.During this period,descending motion was abnormal,convective activity was inhibited,and the degree of drought was increasing over the southwest China.The water vapor flux increased more significantly in the El Nino year than in the La Nina year in autumn over the southwest region and the southern part of the middle and lower reaches of Yangtze River basin,while decreasing over the areas of north and northwest China.The distribution of precipitation in China and the water vapor transport feature of South China Sea in the autumn of 2009 were different from that of normal El Ni o years and even opposite to it.After simple simulation reduction and analysis of the characteristics of El Ni o effect in East Asia in the autumn of 2009,it is considered that the difference mentioned above may be related to the relatively northward location of El Ni o anti-cyclonic circulation. |
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| Keywords: | climatology drought in the southwest china variation of circulation water vapor transport South China Sea the Bay of Bengal ENSO |
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