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气象:2014,40(6):697-705
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卫星水汽通道探测所揭示的高空流场在南亚高压东侧强降水分析中的应用
(国家卫星气象中心,100081)
National Satellite Meteorological Centre, 100081
(National Satellite Meteorological Centre, 100081)
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投稿时间:2013-08-21    修订日期:2014-04-30
中文摘要: 气候平均显示,我国中东部有一类降水和南亚高压脊线的位置有关。逐年资料显示,我国中东部区域平均降水出现在南亚高压脊线的东北侧,在南亚高压东侧脊线北推的过程中呈现两周左右的南北振荡。卫星水汽图可以表征对流层中高层大气运动信息,水汽图像和云导风叠加能够很好描述对流层高层反气旋中心和脊线位置,并且能够追踪对夏季降水非常重要的中高纬度下沉干冷空气活动。中高纬度水汽图上南压的小尺度暗区一般具有正位涡异常,它向雨带的推进可以造成持续降水期间雨量的迅速增强。与南亚高压相关的强降水主要出现在两个区域,一个位于南亚高压的西南侧,另一个位于南亚高压的东北侧,在这两个区域由于气流的发散特征,高层辐散清楚。南亚高压的北侧为副热带西风气流,当西风急流强盛时,高压东北侧的高空为强辐散区,对我国夏季强降水起重要作用。南亚高压的推进和撤退覆盖了我国大部分地区,时间跨度从5月初持续到10月初,因此,针对夏季淮河流域强降水卫星水汽图像特征得出的结论在春秋某些天气过程中也同样具有适用性,并且在比较偏北的西北、华北等地夏季也同样具有某些共同特征。南亚高压位置和形态影响我国降水落区和强度的同时,强降水造成的潜热释放也对南亚高压的非对称不稳定发展起重要作用。
Abstract:In eastern China, there is one kind of rainfall that is related to the upper troposphere anticyclone, i.e., the South Asian High (SAH). The average heavy rainfall of central eastern China in annual cycle happens in the northeastern side of the SAH ridge line and shows a quasi biweekly oscillation in latitude when the SAH ridge line shifts northward or southward. The satellite water vapor (WV) images reveal the atmosphere movement of upper troposphere. The WV image and the derived wind can describe the location of the anticyclone center of upper troposphere and its ridge line and can also trace the downward dry and cold flow from middle high latitude, which is important to heavy rainfall in summer. The small scale dark area extending southward on WV images is usually the strong potential vorticity area in mid high latitude, and it can intensify the rainfall when moving to rainfall belt. There are two severe rainfall areas related to the SAH, one is in the southwest side of the SAH and another is in the northeast side of the SAH where the flow is divergent in the upper troposphere. In the north side of the SAH subtropical westerlies exist when the westerlies are strong, the divergence in the northeast side of the SAH in the upper levels is strong, which can induce strong precipitation in China. The SAH can affect most of China when it advances and withdraws from early May to early October. As a result, the concept model of the satellite image characteristics which is got from the cases over Huaihe River region in summer can also be used in other seasons or places such as Northwest China and North China regions. The location and shape of the SAH can affect the region and intensity of heavy rainfalls and meanwhile severe precipitation also has feedback on the SAH, leading the asymmetric instability development of the SAH.
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基金项目:公益性行业(气象)科研专项(GHYH200906001)和国家自然科学基金项目(41105028)共同资助
引用文本:
任素玲,蒋建莹,许健民,2014.卫星水汽通道探测所揭示的高空流场在南亚高压东侧强降水分析中的应用[J].气象,40(6):697-705.
REN Suling,JIANG Jianying,XU Jianmin,2014.National Satellite Meteorological Centre, 100081[J].Meteor Mon,40(6):697-705.