郭楠楠,周玉淑,邓国. 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, 77(4):686-700, 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 the background of the Central Asian Vortex
投稿时间:2018-10-09  修订日期:2019-01-05
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)、国家重点研发计划项目(2018YFC1507104)、中国气象局乌鲁木齐沙漠气象研究所专项资金项目(IDM2019007)。
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, 北京, 100029
中国科学院大学, 北京, 100049 
 
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, 北京, 100029
中国科学院大学, 北京, 100049 
zys@mail.iap.ac.cn 
邓国 国家气象中心, 北京, 100081  
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全文下载次数: 135
中文摘要:
      为了加强对新疆暴雨过程的中尺度系统发展机理的认识,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气象站观测资料、中国国家卫星气象中心提供的卫星辐射亮温(TBB)资料及WRF高分辨率数值模拟对2013年6月17—18日发生在新疆阿克苏地区的一次暴雨天气过程进行分析。结果表明,此次降水过程是发生在中高纬度“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天气尺度动力及水汽条件;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,山谷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 deepen our understanding of the development mechanism for mesoscale systems that are conductive to torrential rain in Xinjiang Uygur Autonomous Region, this paper analyzes a rainstorm process occurred over the Aksu region in the western Tianshan Mountains during 17-18 June 2013. Various data including the FNL analysis of the U.S. Environmental Prediction Center, the global reanalysis data from the European Center for Medium-range Weather Forecast, the ground automatic weather station data provided by the China Meteorological Administration, the satellite equivalent blackbody brightness temperature data and the WRF high-resolution numerical simulation data are used in the present study. The results show that the precipitation occurred under the background of synoptic circulation with "two-ridge and one-trough" pattern over the middle and high latitudes, and the Central Asian Vortex provided favorable synoptic-scale dynamical and water vapor conditions for this heavy rain event. The convergence line was the most important mesoscale system for this heavy rainfall event, which was formed by the superposition of the Central Asian Vortex circulation and the flow around the special topography of the western Tianshan Mountains. Due to the thermal contrast between the mountains and valley, the downslope wind drove the convergence line to move and strong convection developed along the convergence line, triggering heavy precipitation in Aksu region. The WRF model is able to well simulate not only the location and intensity of the heavy rain, but also the evolution of the wind field. Preliminary analysis of observations and simulation data show that due to the blocking effect of the western Tianshan Mountains, southerly winds converged near the valley. As a result, a local convergence line formed. Meanwhile, following the adjustment of large-scale circulation, especially after the Central Asian Vortex moved to the vicinity of Aksu area, part of the westerly flow in the south of the vortex crossed the western Tianshan Mountains and turned to northwesterly flow, while the remaining part of the westerly flow passed through the Yili Valley and turned to northeasterly winds. These two flows further aggravated northerly winds in Aksu region, and subsequently promoted the formation of mesoscale convergence line. Water vapor brought in by easterly winds in the east of the convergence line accumulated in front of the southern foothill of the Tianshan Mountains. As the valley wind enhanced in the nighttime, the convergence line moved southeastward and continued to intensify. Accompanied with the uplifting of airmass and accumulation of water vapor at the foothill of the mountains, unstable energy was released and heavy precipitation occurred in Aksu region.
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