塔里木盆地东北缘一次强对流天气过程中的阵风锋特征研究

利用地面自动站逐小时观测、多普勒天气雷达及WRF模式高分辨率数值模拟,分析2016年7月塔里木盆地东北缘一次强对流天气过程中的阵风锋特征。结果表明,阵风锋前沿较强的辐合抬升运动不断触发多个对流单体,其中大部分单体与其后方的对流系统合并且进一步发展,使得强对流天气不断发展和维持。在对流系统快速发展阶段,阵风锋前沿水平风的垂直切变造成湿位涡的斜压分量显著增强,从而增强局地的条件对称不稳定,为对流系统的发展和维持提供了重要的不稳定能量。不稳定能量释放需要的锋生强迫作用主要是由阵风锋前方的辐合辐散项和倾斜项决定,而阵风锋前沿附近的水平形变项及其上方的非绝热加热项提供相对较弱的贡献。

Study on the characteristics of a gust front during a severe convective weather process in the northeast margin of the Tarim Basin

The characteristics of a gust front during a severe convective weather process in the northeast margin of the Tarim Basin in July 2016 is investigated based on hourly ground-based automatic weather station data, radar observation data and Weather Research and Forecasting (WRF) model high-resolution simulation data. The results show that the strong convergent lifting effect at the front of the gust front caused the continuous triggering of multiple convective cells at the front of the gust front, most of which merged with the convective system behind it and further developed, resulting in the continuous developed and maintenance of severe convective weather. The analysis of the moist potential vorticity (MPV) characteristics showed that the vertical shear of the horizontal wind at the front of the gust front caused a significant increase in the baroclinic component of the MPV during the rapid development period of the convective system, which enhanced the local conditional symmetric instability (CSI) and provided an important instability condition for the development and maintenance of the convective system. The frontogenetical forcing required for the release of the unstable energy is mainly determined by the convergence and slantwise terms ahead of the gust front, while the horizontal deformation term near the gust front and the diabatic heating term aloft provide relatively weak contributions.