气象2017，Vol.43Issue(6)：665-674,10.DOI:10.7519/j.issn.1000-0526.2017.06.003
低层温度平流对华北雨雪天气过程的降水相态影响分析
Impacts of Low-Level Temperature Advection on the Precipitation Type of Heavy Rain-Snow Process in North China
摘要
Abstract
By using the data of conventional surface and sounding observations as well as the associated NCEP FNL and GFS reanalysis data,the features of precipitation type of heavy rain-snow process in North China during 3-4 November 2012 are studied in this paper.It is found that in the periphery of low-level vortex,the rain and snow separatrix is identical with the 0℃ isotherm and streamline convergence zone between northerly and southerly wind at 925 hPa.However,near the center of low-level vortex,the rain and snow separatrix takes on a feature of anticlockwise revolving from the northwest quadrant to the center of the vortex.In the early stage of cyclone developing,snow is located at the north-northeast quadarant to northwest quadrant of the 850 hPa vortex while the precipitation type at southeast quadrant is rain.As the extratropical cyclone intensifies,temperature at the southwest quadrant of low-level vortex drops quickly due to the low-level cold advection.Therefore,the snow area gradually expands southward along the wind flow of the west side of low-level vortex and takes on a cyclonic-shaped distribution ultimately.The tem-poral evolution of precipitation type depends on the temperature advection of the whole low-level tropo-sphere (850-950 hPa).When there is warm temperature advection in either 900-850 hPa or 950-900 hPa level,the precipitation type may still be rain even if cold advection exists in other levels.The coldtemperature advection of northwest wind at the west side of low-level vortex is very important to snow. When the low-level wind transforms to eastly wind,the low-level cold advection disappears,and finally, the precipitation type involves to rain.关键词
降水相态/低层涡旋/雨雪分界/温度平流Key words
precipitation type/low-level vortex/rain and snow separatrix/temperature advection分类
天文与地球科学引用本文复制引用
杨舒楠,徐珺,何立富,于超..低层温度平流对华北雨雪天气过程的降水相态影响分析[J].气象,2017,43(6):665-674,10.基金项目
北京市自然科学基金(重点)项目(8171002)资助 （重点）
