| 青藏高原中东部夏季降水变化及其与北大西洋涛动的联系 |
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| 引用本文： | 刘晓东,侯萍.青藏高原中东部夏季降水变化及其与北大西洋涛动的联系[J].气象学报,1999,57(5):561-570. |
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| 作者姓名： | 刘晓东 侯萍 |
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| 作者单位： | 中国科学院兰州高原大气物理研究所!兰州，730000 |
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| 基金项目： | 国家与中科院青藏研究项目!KZ951－A1－402，中科院“九五”重大项目!919980408 |
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| 摘 要： | 利用青藏高原中东部地区1961～1990年2000m以上的66个台站夏季（6～8月）降水资料分析了其时空变化特征，发现高原南北降水具有反向变化的特点；结合500hPa高度场及风场资料，讨论了造成高原中东部降水异常的环流特征，指出北大西洋涛动变化可能是影响高原中东部降水的重要原因之一。与北大西洋涛动相联系的中纬度西风异常，通过对高原的西风环流的动力作用的改变，进而引起高原南北槽脊系统的同时加强或减弱，最终造成高原南北部降水的相反变化。
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| 关 键 词： | 青藏高原 夏季降水 经验正交函数 北大西洋涛动 西风环流 |
| 收稿时间： | 4/6/1998 12:00:00 AM |
| 修稿时间： | 1999/1/11 0:00:00 |
VARIATION OF SUMMER RAINFALL OVER QINGHAIXIZANG PLATEAU AND ITS ASSOCIATION WITH THE NORTH ATLANTIC OSCILLATION |
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| Liu Xiaodong and Hou Ping.VARIATION OF SUMMER RAINFALL OVER QINGHAIXIZANG PLATEAU AND ITS ASSOCIATION WITH THE NORTH ATLANTIC OSCILLATION[J].Acta Meteorologica Sinica,1999,57(5):561-570. |
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| Authors: | Liu Xiaodong and Hou Ping |
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| Institution: | Lanzhou Institute of Plateau Atmospheric Physics, Chinese Academy of Sciences, Lanzhou, 730000;Lanzhou Institute of Plateau Atmospheric Physics, Chinese Academy of Sciences, Lanzhou, 730000 |
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| Abstract: | By using 1961 - 1990 summer (June-July-August) rainfall data from 66 stations located at more than 2000m above sea level on the central and eastern Qinghai-Xizang Plateau,the temporal evolutions and spatial structures of the summer rainfall are revealed through theempirical orthogonal function (EOF) analysis. It is found that the dominant spatial patternof the summer rainfall variation over the Plateau is a seesaw between the southern andnorthern parts and the temporal variation of the dominant pattern is closely correlated withthe North Atlantic Oscillation (NAO). A possible mechanism of the correlation is proposedon basis of statistical analyses with the geo-potential height and wind field data over theNorthern Hemisphere. In a summer when the NAO index is low, the westerlies in mid-latitudes from eastern Atlantic to western Europe increases- Enhanced westerlies will bringabout a strong flow around the Plateau when passing the Plateau and so the ridge or anticyclonic vorticity in the northern part and the trough or cyclonic vorticity are strengthened si-multaneously- In this case, the summer rainfall is usually above the normal in the southernPlateau but below the normal in the northern Plateau- In a summer with a high NAO index, the above processes are opposite. |
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| Keywords: | Qinghai-Xizang Plateau Summer rainfall EOF North Atlantic Oscillation Westerly circulation |
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