气象与环境学报Issue(6)：8-14,7.DOI:10.3969/j.issn.1673-503X.2013.06.002
新疆中天山一次城市暴雪过程诊断分析
Diagnostic analysis of an urban snowstorm process in the middle of Tianshan mountains of Xinjiang
摘要
Abstract
Based on the daily NCEP reanalysis data(1°×1°)in four times and the MICAPS conventionally obser-vational data,an urban snowstorm process on March of 2011 in the middle of Tianshan mountains of Xinjiang was diagnosed.The diagnostic study includes a mesoscale analysis,calculations of moisture flux and its divergence,hor-izontal divergence,vertical speed,upper and lower wind fields,helicity and pseudo-equivalent potential tempera-ture.The results indicate that the snowstorm is caused by the eastward movement of the north and south frontal zones after joining up in the central Asia region.The strong southeast wind occurs before snowfall at the urban area of Urumqi.The sharp decompression and warming on the ground provide thermodynamic conditions for the insta-bility energy.There is the southwesterly jet whose wind speed is greater than 30 m·s -1 at 500 hPa,and there exists low-level shear lines at 700 hPa.The vertical distribution of divergence and vertical velocity presents obvious sym-metrical structure of lower-level convergence and upper-level divergence.In the period of heavy snowstorm,it shows a couple of vertical helicity with upper negative and lower positive.The low energy tongue of θse extends upward to 200 hPa,while the high energy tongue of θse maintains from 700 hPa to 400 hPa.The deep moist layer reaches to 300 hPa.This kind of configuration of the physical quantity field accelerates the convergence of wet air in low level and their lifting movement upwards,which provides the necessary conditions for generation of snow-storm.The cold air influences the urban area of Urumqi along a western path.Under the cold air condition,the strong snowstorm usually occurs at the central urban areas with higher temperature due to the effect of urban heat island.Meanwhile,the rainfall center is prone to form in the location of frontal zone.关键词
暴雪/螺旋度/水汽通量Key words
Snowstorm/Helicity/Water vapor flux分类
天文与地球科学引用本文复制引用
万瑜,窦新英..新疆中天山一次城市暴雪过程诊断分析[J].气象与环境学报,2013,(6):8-14,7.基金项目
乌鲁木齐市科技重大项目（Y101330001）、中国沙漠气象科学研究基金（Sqj2009003）和新疆维吾尔自治区气象局青年基金项目（201234）共同资助。 （）
