郭楠楠,周玉淑. 2019. 中亚低涡背景下阿克苏地区一次强降水天气分析[J]. 气象学报, (0):-, doi:10.11676/qxxb2019.040
中亚低涡背景下阿克苏地区一次强降水天气分析
Analysis of a severe precipitation process in Aksu area under background of the Central Asian Vortex
投稿时间:2018-09-27  修订日期:2018-11-05
DOI:10.11676/qxxb2019.040
中文关键词:  暴雨,中亚低涡,地形,数值模拟,辐合线
英文关键词:Rainstorm, Central Asian vortex, Terrain, Numerical simulation, Convergence line
基金项目:国家自然科学基金项目(41661144024、41475054、41475097)共同资助
作者单位E-mail
郭楠楠 中国科学院大气物理研究所云降水物理与强风暴实验室中国科学院大学 guonannan@mail.iap.ac.cn 
周玉淑 中国科学院大气物理研究所云降水物理与强风暴实验室中国科学院大学 zys@mail.iap.ac.cn 
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中文摘要:
      [目的]为了加强对新疆暴雨过程的中尺度系统发展机理的认识,[资料和方法]该文利用美国环境预测中心的FNL、欧洲中期数值预报中心的全球再分析资料、中国气象局提供的地面自动站资料、国家卫星中心提供的卫星相当黑体亮温资料及WRF高分辨率数值模拟对2013 年6月17至18 日发生在西天山的阿克苏地区的一次暴雨天气过程进行分析。[结果和结论]结果表明:此次降水过程是发生在中高纬“两脊一槽”的环流形势下,中亚低涡为这次暴雨的发生提供了有利的大尺度动力水汽条件;中亚低涡环流与天山南脉特殊地形造成的气流绕流相叠加生成的中尺度辐合线是此次强降水的重要中尺度影响系统,山脉和沙漠下垫面的地形热力性质差异造成的下坡风推动辐合线移动,辐合线上发展的强对流引发了阿克苏地区的强降水。WRF模拟结果能够基本再现本次天气过程的降水落区、强度以及风场演变等。结合观测以及模拟资料进行的初步分析显示,西天山的阻挡导致偏南风在西天山南坡山谷附近产生堆积和辐合,山谷附近有局地的地形辐合线形成。同时,随着大尺度环流形势的调整,中亚低涡移动至阿克苏地区附近后,低涡南部的偏西气流一部分直接越过西天山变为西北风,另一部分穿过伊犁河谷之后转为东北风,这两支气流共同加剧了天山南脉阿克苏地区的偏北气流,促进了西天山南坡山谷附近中尺度辐合线的加强。辐合线以东的偏东气流带来的水汽在天山南脉前堆积,随着夜间山谷下坡风的增强作用,中尺度辐合线在向东南方向推进过程中不断发展加强,配合山脚堆积的水汽和辐合抬升,不稳定能量释放,对流发展,为阿克苏地区带来强降水天气。
英文摘要:
      In order to strengthen understanding of the mesoscale system development mechanism in torrential rain over Xinjiang province this paper analyzes a rainstorm process occurred in the Aksu region that is near the west of Tianshan Mountains, during June 17 to 18, 2013 basing on a variety of data that include the FNL data of the US Environmental Prediction Center, the global reanalysis data of the European Interim Numerical Forecast Center, the ground automatic station data provided by the China Meteorological Administration, the satellite''s equivalent blackbody brightness temperature data and WRF high-resolution numerical simulation data. The results show that the precipitation process occurs under the background of the circulation of the two ridges in a trough over the middle and high latitudes, and the Central Asian vortex provides favorable large-scale dynamic and water vapor conditions for this heavy rain. The convergence line is the important mesoscale system of this heavy rainfall which is formed by the superposition of the Central Asian vortex circulation and the flow stream around the special topography of the west Tianshan Mountains. Due to the difference of thermal properties between the mountain and desert, the slope wind drives convergence line to move and the strong convection developed along the convergence line triggers strong precipitation in the Aksu region. The WRF was able to well simulate not only the location and intensity of the heavy rain but also the evolution of wind field. Preliminary analysis combined with observations and simulation data shows that under the blockage of west Tianshan Mountains, the south wind accumulate and convergence near the valley. As a result, a local convergence line is formed. Meanwhile, with the adjustment of the large-scale circulation situation, especially after the Central Asian vortex moved to the vicinity of the Aksu area, one part of the westward flow that came from the south of the vortex turns into northwest wind after crossing the west Tianshan Mountains, and the other part turns into the northeast wind after passing through the Yili Valley, these two flow aggravate the northerly airflow in Aksu region, thereby promote the formation of mesoscale convergence lines and strengthen it. The eastward airflow-induced water vapor accumulates in front of the southern foot of the Tianshan Mountains, and strengthens as the convergence line moves towards southeast with the enhancement of the valley wind at night. Accompanied with the convergence uplift, the accumulation of water vapor at the foot of the mountain promotes the release of unstable energy and brings heavy precipitation to the Aksu region.
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