姚秀萍,张霞,马嘉理,闫丽朱,张硕. 2022. 东亚夏季副热带平原和高原地区切变线特征的对比研究[J]. 气象学报, (0):-, doi:10.11676/qxxb2022.024
东亚夏季副热带平原和高原地区切变线特征的对比研究
Comparative study on the characteristics of shear lines in the subtropical plain and plateau area in East Asia in summer
投稿时间:2021-04-14  修订日期:2021-11-16
DOI:10.11676/qxxb2022.024
中文关键词:  江淮切变线  高原切变线  结构特征  非绝热加热  异同性
英文关键词:the Yangtze-Huaihe shear line  the Tibetan Plateau shear line  structural characteristics  diabatic heating  similarities and differences
基金项目:灾害天气国家重点实验室开放课题(2021LASW-B17),国家自然科学基金项目(42030611、91937301)、第二次青藏高原综合科学考察研究项目(2019QZKK0105)。
作者单位邮编
姚秀萍 中国气象局气象干部培训学院 100081
张霞 河南省气象台 450003
马嘉理 中国气象科学研究院 100081
闫丽朱 河南省气象服务中心 450003
张硕 北京应用气象研究所 450003
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中文摘要:
      生成于东部平原地区的江淮切变线和西部青藏高原地区的高原切变线,都处在东亚副热带相同纬度带上。为深化对地形高度迥异的江淮切变线和高原切变线的认识和理解,本文从切变线与暴雨关系、切变线三维结构特征、切变线附近风场与环流特征以及切变线结构演变中的热力机制等方面对二者进行对比研究。结果表明:(1)江淮切变线分为暖切变线、冷切变线、准静止切变线和低涡切变线4类,高原切变线分为高原横切变线和高原竖切变线2类。江淮切变线与高原切变线均与暴雨关系密切,夏季,有近70%的江淮切变线会产生暴雨,暖切变线暴雨对江淮地区切变线暴雨的雨量贡献最大,低涡切变线暴雨的降水强度最大但发生频率较低;近60%的高原横切变线给高原主体地区带来暴雨,超过55%的竖切变线造成高原东侧及其近邻地区暴雨。(2)江淮切变线与高原切变线均为边界层系统,特征层次分别位于850 hPa和500 hPa。时空尺度上,江淮冷切变线和高原横切变线水平尺度分别可达1000km和2000km,垂直尺度分别可达5km和2km,生命史分别可达48小时和96小时;江淮切变线和高原横切变线在垂直方向上均有从低到高向北倾斜的特征。(3)江淮冷切变线与高原横切变线风场与环流特征存在差异,江淮冷切变线北侧为东北风,南侧为西南风;而高原横切变线东西两段风场有所不同,其西段类似于江淮冷切变线,而东段在不同发展阶段风场有明显变化。(4)江淮冷切变线与高原横切变线的动力结构和热力结构存在差异。动力结构上,二者均位于正涡度带内,正涡度中心强度都在强盛阶段达到最大。热力结构上,江淮冷切变线附近低空锋区特征明显,其西段位于暖湿区内,东段位于干冷区内;而高原横切变线南侧具有明显的高温高湿特征,切变线北侧存在锋区结构。(5)切变线附近的大气非绝热加热与高原横切变线和江淮冷切变线演变关系密切,垂直非均匀加热作用是高原横切变线和江淮冷切变线发展增强最为重要的因子。二者热力结构有差异,减弱机制不同,干冷空气的侵入会导致高原横切变线强度减弱甚至消亡,而江淮冷切变线的强度减弱则与南方暖湿空气的向北侵入有关。
英文摘要:
      The Yangtze-Huaihe shear line(YHSL) generated in the eastern plain and the Tibetan Plateau shear line(TPSL) generated in the western Tibetan Plateau, are both located in the same latitude zone of the subtropical East Asia. In order to deepen the understanding of the YHSL and the TPSH with different terrain heights, this paper carries out a comparative study on the relationship between shear line and rainstorm, the three-dimensional structural characteristics of shear line, the characteristics of wind field and circulation near shear line, and the thermal mechanism in the structural evolution of shear line. The results show that: (1) the YHSLs can be divided into four types, namely warm type, cold type, quasi-stationary type and vortex type. The TPSLs are classified into horizontal TPSH and vertical TPSH. Both of them are closely related to the rainstorm. In summer, nearly 70% of the YHSLs shear line can produce rainstorms. Warm YHSL rainstorm has the largest contribution to the rainfall of YHSL rainstorm, while the vortex YHSL rainstorm has the largest rainfall intensity but low frequency. Nearly 60% of the horizontal TPSLs bring rainstorms to the main area of the Tibetan Plateau, and more than 55% of the vertical TPSLs cause rainstorms to the east side of the Tibetan Plateau and its adjacent areas. (2)Both the YHSL and the TPSH are boundary-layer systems, and the characteristic levels are located at 850 hPa and 500 hPa respectively. On the temporal and spatial scales, the horizontal dimension of the cold YHSL and the horizontal TPSH can reach 1000km and 2000km, the vertical direction can be extended to 5km and 2km, and the life history can last up 48 hours and 96 hours, respectively. Both of them are inclined from low to high to the North in vertical direction. (3)There are differences in wind field and circulation characteristics between the cold YHSL and the horizontal TPSH. The north side of the cold YHSL is northeasterly wind, and the south side is southwesterly wind; while the east and west wind fields of horizontal TPSH are different as the west section is similar to the cold YHSL and the east section varies significantly in different development stages.(4) There are differences in dynamic and thermal structures between the cold YHSL and the horizontal TPSL. In terms of the dynamic structure, the YHSL and the horizontal TPSH are all located in the positive vorticity zone, and the strength of the positive vorticity center reaches the maximum during the strong stage. In terms of thermal structure, the cold YHSL is near the low-level frontal zone, its western section is located in the warm and humid zone and the eastern section is located in the dry and cold zone. While the south side of the horizontal TPSL is highly warm and humid, and there is a frontal zone structure on the north side of the TPSL. (5)The diabatic heating near the shear line is closely related to the evolution of the cold YHSL and the horizontal TPSH. The vertical diabatic heating is the most important factor that causes the development and enhancement of the cold YHSL and the horizontal TPSH. There are differences in thermal structure and weakening mechanism between the cold YHSL and the horizontal TPSH. The invasion of dry and cold air will lead to the weakening or even extinction of the horizontal TPSH, while the weakening of the intensity of the cold YHSL is related to the northward invasion of warm and humid air from the south.
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