Journal of Arid Meteorology ›› 2021, Vol. 39 ›› Issue (1): 65-75.
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REN Li1,2, YANG Yanmin1#br# #br#
Online:
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任丽1,2,杨艳敏1
作者简介:
基金资助:
Abstract: Based on the meteorological conventional observation data, observational precipitation from automatic weather stations and NCEP reanalysis data, the causes and mesoscale characteristics of the heavy rain occurring on July 16, 2019 in Heilongjiang Province under the background of northeast cold vortex were analyzed. The results show that there were two rainstorm areas in the western and eastern Heilongjiang Province affected by MCS and MCC activities, respectively. Both MCS and MCC clouds generated in Inner Mongolia and moved to Heilongjiang Province. Due to the enhanced convective instability and frontal generation, the MCC and MCS clouds developed, strengthened and moved from west to east along the convergence line. In the upper troposphere over the bottom of the cold vortex during the precipitation, there existed a dry intruding airflow with high momentum from the high latitude area. During the process of heavy rain caused by MCC, it presented strong convection instability in the lower atmosphere and moisture symmetry instability in the middle layer. The uplift of ground convergence line and frontal formation promoted the release of unstable energy. MCC was shown as a wide range of mixed cloud precipitation echo on the radar reflectivity products images. One of them was a supercell with hook echo structure, deep cyclone convergence and mesocyclone in middle and lower layers. Compared with MCS, the environmental field of MCC developing had greater vorticity in the middle and lower layers and stronger divergence in the upper layers. The upper levels had stronger pumping action, leading to a stronger upward movement. During the development of MCC, the environmental wind in the middle and lower levels increased significantly. There was greater vertical shear of horizontal wind resulting in stronger organization of mesoscale convective clouds.
Key words: Key words: northeast cold vortex, mesoscale convective complexes, mesoscale convective system, convergence line, convective instability
摘要: 利用常规气象观测资料、自动气象站降水量以及NCEP再分析资料,对东北冷涡背景下黑龙江省2019年7月16日暴雨过程成因及中尺度特征进行诊断。结果表明:2019年7月16日黑龙江省先后受中尺度对流系统(MCS)和中尺度对流复合体(MCC)活动影响,形成2个暴雨区。MCS和MCC云团均在内蒙古生成后移入黑龙江省,由于对流不稳定性增强及锋生作用而发展增强,并沿辐合线自西向东移动。降水期间冷涡底部的对流层高层存在一支源于高纬地区高动量的干侵入气流。MCC引发的暴雨过程中,大气低层强对流不稳定,中层湿对称不稳定,地面辐合线及锋面锋生的抬升作用,促使不稳定能量释放。在雷达反射率因子图上MCC表现为大范围混合云降水回波,其中有超级单体活动。MCC发展的环境场较MCS而言,中低层气旋涡度更大,高层辐散更强,即高层具有更强抽吸作用,导致更强的上升运动。MCC发展过程中中低层环境风显著增大,具有更大的水平风垂直切变,中尺度对流云团更具组织性。
关键词: 关键词:东北冷涡, MCC, MCS, 辐合线, 对流不稳定
REN Li, YANG Yanmin. Dynamic and Thermal Characteristics of a Heavy Rain Caused by MCC at Bottom of Northeast Cold Vortex[J]. Journal of Arid Meteorology, 2021, 39(1): 65-75.
任丽, 杨艳敏. 东北冷涡底部一次MCC暴雨动力热力特征分析[J]. 干旱气象, 2021, 39(1): 65-75.
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