Journal of Arid Meteorology

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Mechanism of Two β Scale Rain Belts in the MCS

LUO Juan1, FENG Jiaxiong2, CHEN Muxi3   

  1. 1. Chongqing Meteorological Bureau, Chongqing 401147, China;
    2. Wuxi Meteorological Station of Chongqing, Wuxi 405800, Chongqin, China;
    3. Chengkou Meteorological Station of Chongqing, Chengkou 405900, Chongqin, China
  • Online:2018-06-30 Published:2018-06-30

中尺度对流系统内β尺度双雨带不稳定机制及锋生对比分析

罗娟1冯家兄2陈沐希3   

  1. 1. 重庆市气象局,重庆401147;2. 重庆巫溪县气象局,重庆巫溪405800;
    3. 重庆城口县气象局,重庆城口405900

Abstract:

Based on the conventional observation data,TBB data of FY-2G satellite and the NCEP reanalysis data with 1°×1°spatial resolution, the evolution of the two meso-β scale rain belts in the meso-scale convective systems (MCS) during a heavy rain process in Chongqing on 1-2 June 2016 was analyzed, and on this basis, the differences of frontal zone, frontogenesis and unstable mechanism between the two rain belts were compared emphatically. The results are as follows: (1) This heavy rain process was caused by MCS, and there were two meso-β scale rain belts in the MCS, they were located separately in the south and north sides of the maximum TBB gradient zone. (2) The north rain belt was located in the lower front area, and it was a meso-scale rain band and nearly being parallel to the front, while the south rain belt was located in front of the frontal zone with high humidity and energy, and thus it had stronger convective precipitation compared to that of the north rain belt. (3) The frontogenesis function contributed differently to the two rain belts. The north rain belt was characterised with horizontal divergence movement of strong frontogenesis, while the south rain belt was focused on the vertical motion. And these differences were related to the atmospheric stratification stability. (4) It was significantly different instability mechanism between the north and the south rain belt. The south rain belt was caused by convective instability mechanism. However, for the north rain belt, along the frontal surface the oblique updraft developed towards cold zone, which was as a result of symmetric instability mechanism.

Key words:  MCS, meso-&beta, mesoscale rain belt, frontogenesis, convective instability, symmetric instability

摘要:

利用常规观测资料、FY-2G卫星TBB资料和NCEP(1°×1°)再分析资料,分析造成2016年6月1—2日重庆地区暴雨天气过程的MCS及内部2条β中尺度雨带的演变特征,并着重对比分析2条雨带锋区、锋生及不稳定机制的差异。结果表明:(1)此次暴雨天气过程由MCS造成,其内部有南、北2条β中尺度雨带,分别位于MCS南、北两侧TBB梯度大值区;(2)北雨带位于低层锋区内,是一条与锋面近于平行的中尺度雨带,而南雨带位于锋区前缘的高湿区和高能区中,对流性降水更强;(3)锋生函数各项对南北雨带锋生贡献有显著不同,北雨带以水平运动作用锋生为主,而南雨带则以垂直运动作用锋生为主,南北雨带锋生各项这种差异,与大气层结稳定度有关;(4)南北雨带不稳定机制有显著不同,南雨带为对流性不稳定机制,北雨带沿着锋面有向冷区倾斜的斜升气流发展,为对称不稳定机制。

关键词: MCS, &beta, 中尺度雨带, 锋生, 对流不稳定, 对称不稳定