西藏高原两次历史性暴雪天气过程对比分析

Comparative analysis of two historic snowstorm weather processes in Tibet plateau

利用TRMM 3B42降水资料和ERA-Interim再分析资料,对西藏高原2008年10月26—29日和2013年10月13—14日两次暴雪天气过程进行了对比分析。结果表明,2008年以错那县为主的藏东南地区暴雪过程属于西太平洋副热带高压型,主要的影响系统是500 hPa上南支槽和西太平洋副热带高压;2013年以聂拉木县为主的藏南地区暴雪过程则属于印度低压型,主要的影响系统是850 hPa上的低压系统及低空急流,500 hPa上印度北部低涡气旋和孟加拉湾北部高压单体;2008年暴雪过程的暴雪区域在水汽通量带左侧,而2013年暴雪区域在水汽通量高值中心前方;2008年暴雪过程的物理量配置比2013年暴雪过程更好。两次暴雪天气过程的暴雪落区和高湿区相对应,湿层厚度也基本一致;暴雪落区与水汽通量辐合区相一致;上升运动区与暴雪落区相对应;暴雪区域都位于能量锋区上,锋区两侧中低层冷暖气流汇合加剧暴雪区域的垂直上升运动。

Using TRMM 3 B42 precipitation data and ERA-Interim reanalysis data,the two snowstorm weather processes on the Tibetan plateau on October 26—29,2008 and October 13—14,2013 were compared and analyzed.The results showed that in 2008,the snowstorm weather process in southeastern Tibet,dominated by Cuona county,belonged to the western Pacific subtropical high type.The main influence systems were the 500 hPa upper southern branch trough and the western Pacific subtropical high;In 2013,the blizzard in southern Tibet,dominated by Nyalam county,which was of the Indian low pressure type;The main impact system was the low-pressure system on 850 hPa and the low-altitude jet stream,500 hPa low vortex cyclone in northern India and high pressure monomer in northern Bay of Bengal;The snowstorm area during the 2008 snowstorm was on the left side of the water vapor flux zone,but the 2013 snowstorm area was in front of the center of high water vapor flux;The physical configuration of the 2008 snowstorm process was better than that of the 2013 snowstorm process.The snowstorm falling area during the two snowstorm corresponds to the high humidity area,the thickness of the wet layer was basically the same;The snowstorm falling area was consistent with the water vapor flux convergence area;The ascending movement zone corresponded to the snowstorm falling zone;Snowstorm areas were all located above the energy front area.The snowstorm areas were all located on the energy front zone,and the confluence of the cold and warm air flows on both sides of the front zone aggravated the vertical upward movement of the snowstorm area.