利用中国气象局逐小时区域站、 高空站、 逐小时风云2E卫星、 NCEP再分析数据资料以及WRF数值模式, 选取2018年8月1 -3日降水天气过程, 分析高原切变线形态演变对发生在高原边坡降水的影响。结果表明: （1）8月1 -3日降水过程主要影响系统为高原切变线, 1日和2日分别为此次降水过程的两个不同阶段, 两个降水阶段期间高原切变线由横切变线转为竖切变线; （2）在高原边坡, 与横切变线引起的降水相比, 竖切变线更容易产生强对流天气; （3）强降水发生时, 竖切变线激发的TBB值比横切变线的TBB值低10~20 K, 且TBB低值刚好与短时强降水发生的时间段相对应; （4）数值模式模拟结果表明在强降水发生阶段, 竖切变线的垂直速度、 水汽含量、 不稳定能量垂直梯度均表现为快速增强, 且增强的幅度明显大于横切变线的对应物理量; 此外, 降水强度的变化与垂直速度上升高度、 不稳定能量垂直梯度有很好的对应关系。
Based on hourly regional stations data, upper-air stations data and FY2E satellite data from China meteorological administration, NCEP reanalysis data and WRF model, the precipitation weather process on August 1-3, 2018 was selected to analyze the influence of the evolution of plateau shear line on the plateau slope, The results indicates that: (1) The plateau shear line is the main influence system in this process, days 1 and 2 are two different stages of the precipitation process, during which the plateau shear line changes from a transverse shear line to a vertical shear line.(2) Compared with the precipitation caused by transverse shear, Vertical shear is likely to cause strong convective precipitation.(3) When heavy precipitation occurs, the TBB value excited by the Vertical shear is 10~20 K lower than that of the transverse shear, and the low value of TBB is consistent with the time period of short-time heavy precipitation.(4) The model simulation results of these two processes generally show better skill.During the period of heavy precipitation, the vertical velocity, water vapor content and the vertical gradient of unstable energy of the vertical shear show rapid enhancement, and the amplitude of enhancement is obviously larger than that of the transverse shear, in addition, the change of precipitation intensity has a good correspondence with vertical velocity rising height and unstable energy vertical gradient.
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