辽宁地区一次暴雪过程低涡增强机制分析
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摘要
利用常规气象观测资料和NCEP/NCAR再分析资料,对2015年2月15—17日辽宁省东北部地区一次暴雪天气过程的低涡增强机制进行了分析。结果表明:辽宁地区此次暴雪过程中850 h Pa低涡增强最明显,绝对涡度平流项是高层正涡度变率的主要强迫项,散度项则是低层正涡度变率的主要强迫项;500 h Pa冷平流增强强迫高层正涡度变率发展,造成涡度在垂直方向上分布不均匀,差动涡度平流增大,垂直上升运动加强,低层辐合加强,使低层涡度增强,低层低涡系统发展,低层低涡系统发展使干冷的西北气流、东北气流和来自黄海北部的东南暖湿气流在辽宁中部地区汇合,降雪加强。
Based on conventional meteorological observational data and NCEP/NCAR( National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data,the enhancement mechanism of the lowvortex in a snowstorm from February 15 to 17,2015 over the northeast of Liaoning province is analyzed.The results showthe enhancement of lowvortex at 850 h Pa is the most obvious during the snowstorm event. The absolute vorticity advection term is the major forcing source for the positive vorticity tendency in the upper levels,and the divergence term is the main forcing source for the positive vorticity variability in the lower levels. The enhancement of cold advection at 500 h Pa forces the development of positive vorticity variability in the upper levels,resulting in the heterogeneous vertical distribution of vorticity,the increasing differential vorticity advection,the enhancement of vertical ascending motion,and the strong convergence in lower levels. The development of lowvortex system in the lower levels results in the convergence of dry and cold northwesterly and northeasterly flows and warm and wet southeasterly flows from the north YellowSea over the central region of Liaoning province,which strengthens the snowfall.
Based on conventional meteorological observational data and NCEP/NCAR( National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data,the enhancement mechanism of the lowvortex in a snowstorm from February 15 to 17,2015 over the northeast of Liaoning province is analyzed.The results showthe enhancement of lowvortex at 850 h Pa is the most obvious during the snowstorm event. The absolute vorticity advection term is the major forcing source for the positive vorticity tendency in the upper levels,and the divergence term is the main forcing source for the positive vorticity variability in the lower levels. The enhancement of cold advection at 500 h Pa forces the development of positive vorticity variability in the upper levels,resulting in the heterogeneous vertical distribution of vorticity,the increasing differential vorticity advection,the enhancement of vertical ascending motion,and the strong convergence in lower levels. The development of lowvortex system in the lower levels results in the convergence of dry and cold northwesterly and northeasterly flows and warm and wet southeasterly flows from the north YellowSea over the central region of Liaoning province,which strengthens the snowfall.
引文
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[3]Ninomiya K.Polar low development over the east coast of Asian continent on 9-11 December 1985[J].Journal of the M eteorological Society of Japan,1991,69(6):669-685.
[4]Sanders F,Bosart L F.Mesoscale structure in the Megalopolitan Snow storm of 11-12 February 1983.Part I:Frontogenetical forcing and symmetric instability[J].Journal of the Atmospheric Sciences,1985,42(10):1050-1061.
[5]张楠,易笑园,朱丽娟,等.地面气旋影响下两次华北暴雪(雨)过程分析[J].气象与环境学报,2014,30(5):7-14.
[6]吴振玲,汪靖,赵刚,等.天津地区一次大到暴雪天气的诊断分析[J].气象与环境学报,2012,28(6):8-13.
[7]张小玲,程麟生.“96.1”暴雪期中尺度切变线发生发展的动力诊断I:涡度和涡度变率诊断[J].高原气象,2000,19(3):285-294.
[8]张小玲,程麟生.“96.1”暴雪期中尺度切变线发生发展的动力诊断Ⅱ:散度和散度变率诊断[J].高原气象,2000,19(4):459-466.
[9]王文,程麟生.“96.1”高原暴雪过程湿对称不稳定的数值研究[J].高原气象,2000,19(5):129-140.
[10]王文,程麟生.“96.1”高原暴雪过程三维条件性对称不稳定的数值研究[J].高原气象,2002,21(3):225-232.
[11]阎琦,蒋大凯,陈传雷,等.1960—2009年辽宁区域性暴雪气候特征[J].气象与环境学报,2012,28(4):43-48.
[12]蒋大凯,乔小湜,张宁娜,等.2009年2月辽宁一次暴雪过程动力条件诊断[J].气象与环境学报,2012,28(1):17-23.
[13]陈传雷,蒋大凯,陈艳秋,等.2007年3月3—5日辽宁特大暴雪过程物理量诊断分析[J].气象与环境学报,2007,23(5):17-25.
[14]孙欣,蔡芗宁,陈传雷,等.“070304”东北特大暴雪的分析[J].气象,2011,37(7):863-870.
[15]朱乾根,林锦瑞,寿绍文,等.天气学原理和方法(3版)[M].北京:气象出版社,2000:113-116,123-126.