高原低涡东移出高原的平均环流场分析

Analyses on Mean Circulation Field of the Plateau Low Vortex Moving Out of Tibetan Plateau

利用美国国家环境预测中心（NCEP）再分析资料，挑选出1998-2004年夏季高原涡移出高原多、少的年、月对它们的环流场进行对比分析。对比分析指出，6～8月是高原涡最易移出的月；当500hPa盂湾季风槽偏北，或西太副高明显西伸，高原东部有切变线活动；当200hPa南亚高压东伸明显，高原东部为南亚高压脊前西北气流控制时，有利于高原涡东移出高原。为高原低涡暴雨预报的气候背景提供了科学依据。

Using the NCEP reanalysis data, the activity characteristics of the Plateau low vortex moving out of the Tibetan Plateau in each month in summer from 1998 to 2004 are analyzed. Furthermore, the compared analysis of the monthly mean geopotential height, geopotential height difference distribution, temperature; wind field between the more vortex moving out of the Plateau in June, July and August and less vortex moving out of the Plateau rule is gotten. The different characteristics between the Plateau vortex over the Plateau and the vortex moving out of the Plateau and the mean circulation field characteristics of the Plateau vortex moving out of the Plateau were acquired. All this had offered a scientific background for the prediction of the Plateau vortex which lead to the storm rainfall.