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气象:2015,41(7):816-824
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南疆西部持续性暴雨环流背景及天气尺度的动力过程分析
(1.新疆气象台,乌鲁木齐 830002;2.93886部队气象中心,乌鲁木齐 830000)
Analysis of Continuous Rainstorm Circulation Background and the Dynamic Process of Synoptic Scale in West of Southern Xinjiang
(1.Xinjiang Meteorological Observatory, Urumqi 830002;2.Unit of 93886 of People’s Liberation Army, Urumqi 830000)
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投稿时间:2014-06-12    修订日期:2015-04-13
中文摘要: 2013年6月14—19日南疆西部出现了持续性暴雨,使用常规观测资料和NCEP再分析资料在讨论环境大气湿度条件与暴雨关系的基础上,分析了水汽远距离输送到新疆并在南疆上空积累的天气尺度动力过程及其形成的原因。结果表明,暴雨产生在大气异常潮湿的环境中,强降雨时段对流层低层比湿最大值达到16~18 g·kg-1。长时间强降水的重要原因是边界层以上高湿的特征在暴雨产生过程中一直维持,充沛的水汽被一支从阿拉伯海和孟加拉湾的偏南气流向北输送,偏南风持续增速加大了水汽的输送。同时,随着偏南气流向北靠近新疆,对流层低层偏东急流在南疆西部产生强的水汽通量辐合,使得高空强烈辐散与低空辐合之间的耦合不断加强,不仅增加了低层水汽在暴雨区汇集,也通过增强垂直速度将更多的潮湿空气向上输送,使高层大气湿度增加。暴雨的日变化与阿克苏南部中尺度垂直环流圈的间断性建立及低层偏东急流在夜间增强有关。
Abstract:The continuous rainstorm appeared in West of Southern Xinjiang from 14 to 19 June 2013. The convention observation, T639, NCEP reanalysis data are used in the analysis in order to know why the rainfall could be so much. Based on the relation between environmental air humidity conditions and the rainstorm, this paper analyzed the weather scale dynamic process and its forming reasons why the water vapor was transmitted over a long distance to Xinjiang, getting accumulated over the West of Southern Xinjiang. The results showed that rainstorm develops in an abnormal environment. During heavy rainfalls the top value of specific humidity reaches to 16-18 g·kg-1 in the lower troposphere. The extreme humid situation maintains even though the heavy rain appears, which is favorable for the long lasting severe rainstorm. The abundant water vapor is transported from Arabian Sea and Bay of Bengal to West of Southern Xinjiang by a southern flow. The southern wind increased the water vapor transfer. At the same time, with the southern airflow’s approaching Xinjiang, strong water vapor flux convergence is generated by low level troposphere eastern jet stream in West of Southern Xinjiang, making the strong couple between upper level divergence and low level convergence of vapor lower, and also strengthening the ascending velocity and inducing more wet air to higher altitude and then thickening the moisture layer further. The diurnal variation of the heavy rain is related to the vertical discontinuity of mesoscale circulation circle in Aksu southern and the low level easterly jet enhancements at night.
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基金项目:国家科技支撑计划项目(2012BAC23B01)、中国沙漠气象科学研究基金(Sqj2012004)和中国气象局预报员专项(CAMYBY2014 080)共同资助
引用文本:
张云惠,李海燕,蔺喜禄,阿不力米提,于碧馨,2015.南疆西部持续性暴雨环流背景及天气尺度的动力过程分析[J].气象,41(7):816-824.
ZHANG Yunhui,LI Haiyan,LIN Xilu,Abulimiti,YU Bixin,2015.Analysis of Continuous Rainstorm Circulation Background and the Dynamic Process of Synoptic Scale in West of Southern Xinjiang[J].Meteor Mon,41(7):816-824.