摘要
利用多种资料对黑龙江省两次由江淮气旋和蒙古气旋合并引发的暴雪过程的水汽、热动力条件和中尺度特征进行了对比分析。结果表明:(1)两次暴雪过程都发生在北支槽和短波槽合并、北支槽北部有冷涡的背景下,850 h Pa上低涡合并促使江淮气旋和蒙古气旋合并;气旋合并后,低空急流为降雪提供了充足水汽,强暖平流使气旋爆发性发展,导致降雪加强。(2)两次降雪过程都表现出逗点云系的合并发展,"1211"暴雪过程中高层形成涡旋偏西,700 h Pa低涡东部偏南风引导气旋北上西折,低空急流和地形共同作用使暖湿空气强烈辐合上升,产生对流云,暴雪发生在A类逗点云系的头部,降雪强度大,范围广;"1412"暴雪过程高空槽低涡位置偏东,700 h Pa低涡东部西南风始终引导气旋向东北方向移动,近地面层具有冷垫,暴雪主要发生在B类气旋逗点云系头部西侧中低云团中,降雪范围和强度较"1211"过程小。(3)低层(0. 3 km)冷空气侵入和中高层(5. 5 km)转为偏北风对判断降雪开始和结束有很好的表征意义。(4)冷涡前部强高压脊使冷涡移动缓慢,从而延长了降水的持续时间,气旋移动路径与高压脊伸展方向密切相关。
Water vapor, thermal and dynamic conditions and mesoscale features of two snowstorm processes in Heilongjiang Province caused by the merger of Jiang-Huai cyclone and the Mongolian cyclone were compared and analyzed by using various data. The results show that:(1) The two snowstorms occurred in the merger of the north branch trough and the shortwave trough, and then a cold vortex formed in the north of the north branch trough, the low vortex combined at 850 hPa, resulting in a merger of the Jiang-Huai cyclone and the Mongolian cyclone;after the cyclone merged, the low-level jet stream provided sufficient water vapor for the snowfall, and the strong warm advection made the cyclone explosively developing and strengthening the snowfall. (2) Comma cloud system developed combinedly in the two snowfalls. A high-level vortex formed by west during the "1211" snowstorm. The southerly wind in the eastern part of the 700 hPa low vortex guided the cyclone northwards and west-northwestwards. The eastward wind of 700 hPa low vortex southerly guided the cyclone north to the west, and the low-level jet stream and the topography worked together to make the warm and humid air rise strongly, resulting in convective clouds. Snowstorm occurred at the head of a A-type comma cloud system, and had a large snowfall intensity and a wide range;in the "1412" snowstorm case, the high-altitude trough low-vortex position was eastwards, and the 700 hPa low-vortex east-west wind always guided the cyclone to move to the northeast. There was a cold wedge in the near ground layer. Snowstorm mainly occurred in the middle and low cloud clusters on the west side of the head of the B-type cyclone comma cloud system, and the snowfall range and intensity were smaller than the "1211" cases. (3) The cold air of the lower layer (0.3 km) invasion and the transition of the upper layer (5.5 km) to the northerly wind had a good representational significance for judging whether the snowfall starts and ends. (4) The strong ridges in the front of the cold vortex moved the cold vortex slowly, which prolonged the duration of precipitation, and the cyclone moving path closely related to its direction.
作者
周显伟
赵宇
祝玉梅
娄德君
ZHOU Xianwei;ZHAO Yu;ZHU Yumei;LOU Dejun(College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China;Qiqihar Meteorological Bureau, Qiqihar 161006, Heilongjiang, China)
出处
《冰川冻土》
CSCD
北大核心
2018年第6期1195-1206,共12页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(41475038
41475090)资助
关键词
暴雪
温带气旋
逗点云系
冷垫
snowstorm
extra-tropical cyclone
comma cloud system
cold pad