2009号台风“美莎克”对黑龙江的影响及非对称结构特征

使用常规观测资料及ERA5（0.25°×0.25°）再分析资料,对2009号台风“美莎克”进行分析。结果表明：此次过程,副热带高压异常强大,位置偏北,并与北侧阻高合并形成高压坝阻挡;“美莎克”沿副高外围北上与中纬度低涡及冷空气相互作用,变性后斜压性明显加大,低涡增强;“美莎克”携带大量水汽,同时中低空急流将海上水汽持续向黑龙江输送,并在黑龙江强烈辐合,形成强的水汽辐合区和水汽辐合带;高低空急流耦合构成强的垂直环流,对应非常强的垂直上升速度;副热带高压向西北伸展,高空引导气流和热成风方向转为西北—东南向,促使“美莎克”登陆后向西北移动,穿过黑龙江,是黑龙江出现大暴雨的主要原因。分析台风中心涡度、散度、垂直速度、位温、湿位涡等物理量的三维结构变化,可以很好地认识台风在北上登陆中的变性过程以及降水出现非对称结构的原因。

Influence of Typhoon Maysak (2009) on Heilongjiang Province and its asymmetric structure characteristics

Using conventional observation data and ERA5 (0.25° × 0.25°) reanalyzed data to analyze "Maysak". The results show that in this process, the subtropical anticyclone was unusually strong, combined with the blocking high on the north side to form a high-pressure dam. "Maysak" moved northward along the periphery of the subtropical anticyclone and interacted with the middle latitude vortex and cold air, and then the baroclinic property obviously increased and the vortex enhanced. "Maysak" carried a large amount of water vapor, and at the same time, the middle and low-level jet stream continuously transported water vapor to Heilongjiang, and strongly converged in Heilongjiang, forming a strong water vapor convergence area and water vapor convergence belt. The coupling of high and low level jet flow formed a strong vertical circulation, which corresponded to a very strong vertical ascending velocity. The subtropical anticyclone extended to the northwest, and the direction of the steering flow and thermal wind turned to the northwest-southeast direction, prompting the "Maysak" to move to the northwest and pass through Heilongjiang after landing, which was the main reason for the heavy rain in Heilongjiang Province. By analyzing the three-dimensional structural changes of the physical quantities such as the vorticity, divergence, vertical velocity, potential temperature and wet potential vorticity of the Typhoon center, we can understand the variability process of the Typhoon during its northward landing and the cause of the asymmetric structure of precipitation.