Abstract

The results of the numerical simulation of intense convection that caused the tornado in the city of Blagoveshchensk on July 31, 2011 are presented. The WRF-ARW nonhydrostatic mesoscale model on the nested grids with the spacing to 500 m is used for simulations. It is found that the tornado was initiated by the meso-γ vortex associated with a quasilinear convective system at the height of 700–900 m. The mesovortex was generated when the wind shear in the lower 2-km layer was 21–27 m/s and convective available potential energy was to 1800 J/kg. The position and center of the mesovortex were specified by the values of vorticity and the Okubo–Weiss number. The simulated tornado was formed close to this mesovortex. The main contribution to the intensification of vertical velocity in the tornado was made by the perturbations of pressure and buoyancy and that to vorticity was made by the horizontal advection. The simulated time of occurrence, location, and duration of the event slightly differ from the real ones.

中文翻译：

---

2011年7月31日在布拉戈维申斯克造成强烈龙卷风的强对流数值研究

摘要

给出了2011年7月31日在布拉戈维申斯克市引起龙卷风的强对流数值模拟的结果。嵌套网格上WRF-ARW非静水中尺度模型的间距为500 m，用于仿真。发现龙卷风是由与准线性对流系统有关的中γ涡旋在700–900 m高度引发的。当下部2 km层的风切变为21–27 m / s，对流可用势能为1800 J / kg时，产生了中涡。中涡的位置和中心由涡度值和Okubo-Weiss数确定。模拟龙卷风在靠近该中涡形成。对龙卷风垂直速度的增强的主要贡献是由压力和浮力的扰动引起的，而对涡旋的影响则是由水平对流引起的。事件的模拟发生时间，位置和持续时间与实际时间略有不同。