Structure and Environment of Polar Mesocyclones over the Northeastern Part of the Sea of Japan
Structure and Environment of Polar Mesocyclones over the Northeastern Part of the Sea of Japan
复制标题
日本海东北部极地中气旋的结构与环境
DOI：
10.1175/mwr-d-16-0342.1
复制
发表时间：
2017
影响因子：
3.2
通讯作者：
Yanase Wataru
中科院分区：
文献类型：
--
作者：
Watanabe Shun-ichi I.;Niino Hiroshi;Yanase Wataru
极地中气旋(PMC)是主要极锋向极地发展的中尺度气旋性涡旋。日本海是冬季临时气候变化频繁发生的地区之一。本文采用合成分析和数值模拟相结合的方法，研究了形成于日本海东北部并向南移动的PMC的结构和环境的一般特征。综合分析表明，该区域的天气尺度环境具有低层纬向温度梯度和高层低槽伴随冷空气的特征。环境领域的这些要素形成了反向剪切。PMCs的中尺度结构表现出斜压发展的特征，但也伴随着凝结加热。用复合场作为初始条件和边界条件的数值模拟成功地再现了真实的PMC。在该数值模拟中，初始场和边界场中的中尺度结构几乎被平滑，这表明当大尺度环境变得有利时，PMCs自发形成和发展。去湿的敏感性实验表明，凝结加热对PMC的发生和发展是至关重要的。敏感性试验还表明，塔尔特利海峡和北海道以西日本海温暖的海面温度，以及锡霍特-阿林山地区的地形，为太平洋气候中心的发展提供了有利的条件。
Polar mesocyclones (PMCs) are mesoscale cyclonic vortices that develop poleward of the main polar front. The Sea of Japan is one region where PMCs frequently occur during winter. In this paper, the general characteristics of the structure and environment of PMCs that form over the northeastern part of the Sea of Japan and move southward are examined using composite analysis and numerical simulation. The composite analyses show that the synoptic-scale environment of the PMCs is characterized by a zonal temperature gradient at lower levels and a trough accompanied by cold air at upper levels. These elements of the environmental field form a reverse shear. The mesoscale structure of the PMCs exhibits characteristics of baroclinic development, while it is also accompanied by condensational heating. The numerical simulation in which the composite fields are used for the initial and boundary conditions successfully reproduces a realistic PMC. In this numerical simulation, the mesoscale structures are almost smoothed out in the initial and boundary fields, indicating that the PMCs spontaneously form and develop when the large-scale environment becomes favorable. Sensitivity experiments in which moisture is removed demonstrate that condensational heating is crucial for the genesis and development of the PMC. The sensitivity experiments also show that the warm sea surface temperature in the Strait of Tartary and the Sea of Japan to the west of Hokkaido Island, and the topography of the Sikhote-Alin mountain region provide favorable conditions for the development of the PMCs.