摘要
以NCEP资料为初始场和侧边界条件,利用WRF模式对东、西天山地形对2015年12月9—12日大暴雪影响进行敏感性试验,从降水强度和分布等方面对比分析模拟结果,探讨地形在暴雪过程中的作用,对成因进行初步研究分析,结果表明:(1)此次强降雪发生是高空西南急流抽吸、低层风切变及风速辐合、偏北风与地形强迫抬升、地面冷锋移动缓慢等共同造成的。(2)此次暴雪天气过程,地形对强降雪的落区、强度影响很大,东、西天山高度与强降雪强度正相关,东、西天山高度降低、强降雪落区沿环流方向移动。(3)地形动力强迫整体上增强次级环流圈。近地面上升速度中心出现在迎风坡山脚至山腰区域,并向两侧递减,与此次大暴雪中心落区以及乌鲁木齐附近测站降雪量分布吻合,东、西天山地形高度降低50%,近地面上升速度中心值减少30%。地形强迫东、西天山峡谷近地面生成辐合中心和辐合线,辐合中心强度与地形高度正相关。(4)地形强迫抬升有加强水汽辐合汇聚的作用,东、西天山地形高度降低50%,水汽通量与水汽通量散度减少30%。
Using NCEP data as initial field and lateral boundary conditions,sensitivity experiments on the impact of terrain on the East and West Tianshan mountains during an extreme blizzard are performed with the WRF model.Comparing precipitation intensity,distribution and other aspects,results show that:(1)the occurrence of extreme blizzard is caused by upper southwest jet pumping,low-level wind shear,wind speed convergence,north wind,orographic forced uplift and slow movement of cold front.(2)The topography has a great influence on the falling area and intensity of heavy snowfall.The altitude of the East and West Tianshan Mountains is positively related to the intensity of heavy snowfall.The altitude of the East and West Tianshan Mountains decreases and the falling area of heavy snowfall move along the circulation direction.(3)The orographic forcing enhances the secondary circulation.The center of rising velocity near ground is on the windward slope from the foot of mountain to the mountainside,it coincides with the extreme blizzard center and the snowfall distribution nearby Urumqi station.The altitude of the East and West Tianshan Mountains decreases by50%,the strength of rising velocity center near ground decreases by30%.The terrain force produces the convergence center and convergence line near the ground in the Tianshan valley,and the intensity of convergence center is positively related to the terrain height.(4)The orographic forcing enhances the convergence of water vapor convergence.The altitude of the East and West Tianshan Mountains decreases by50%,the water vapor flux and water vapor flux divergence decrease by30%.
作者
朱雯娜
张茜
谭艳梅
ZHU Wenna;ZHANG Qian;TAN Yanmei(Meteorological Center of Xinjiang Air Traffic Management Bureau,Urumqi 830016,China;School of Atmospheric Sciences,Nanjing University,Nanjing 210093,China)
出处
《沙漠与绿洲气象》
2017年第4期62-69,共8页
Desert and Oasis Meteorology
基金
中央级公益性科研院所基本科研业务费专项(IDM2016001)
关键词
暴雪
地形敏感性
次级环流
extreme blizzard
terrain sensitivity
secondary circulation
作者简介
朱雯娜（1983-），女，工程师，从事航空气象和数值模拟研究。E-mail:juju8343@163.com
