Structural Characteristics of the Spring Transverse Shear Line over the Qinghai-Tibet Plateau and the Influence Mechanism of the Upper-level Jet on Its Evolution  

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作  者:Qin GUAN Xiaoyan SHEN Qingping LI 

机构地区:[1]Qinghai Provincial Meteorological Observatory,Xining 810001,China [2]Qinghai Institute of Meteorological Science,Xining 810001,China [3]Huangnanzhou Meteorological Office of Qinghai Province,Tongren 811300,China

出  处:《Meteorological and Environmental Research》2022年第2期28-37,40,共11页气象与环境研究(英文版)

基  金:Supported by Project of Qinghai Science and Technology Department (2020-ZJ-739);Project of Key Laboratory for Disaster Prevention and Mitigation of Qinghai Province (QFZ-2021-Z04);Key Project of Qinghai Provincial Meteorological Bureau (QXZ2020-03)

摘  要:Based on the four-times-daily ERA-Interim data with the resolution of 0.75°×0.75°,the structure and evolution characteristics of a transverse shear line(TSL)over the Qinghai-Tibet Plateau in April 2017 were analyzed,and the influence mechanism of the frontogenesis and frontolysis caused by the upper-level jet on its evolution was also investigated.The results show that the TSL was mainly located near the axis of the positive vorticity zone,which was a low-value area of the wind speed.It was a shallow baroclinic system with weak ascending motion.In the vertical direction,the TSL extended to the lowest height at 00:00 and the highest at 18:00.In the horizontal direction,the length of the TSL in the east-west direction was relatively shorter during 00:00-06:00 and relatively longer during 12:00-18:00.Besides,the position of the TSL was slightly northward at 06:00 and slightly southward at 18:00.The moving direction of the TSL was generally consistent with that of the upper-level jet.In addition,the vertical stretching height of the TSL and the near-surface wind speed were positively correlated with the intensity of the upper-level jet.The calculation by frontogenesis function indicates that the frontogenesis(frontolysis)was conducive to the formation(weakening)and strengthening(dissipation)of the TSL.The horizontal deformation-induced and diabatic heating-induced frontogenesis were favorable for the formation of the TSL,while the middle-level horizontal convergence-induced and diabatic heating-induced frontogenesis were beneficial to its maintenance.Besides,the moving direction and baroclinicity of the TSL over the Qinghai-Tibet Plateau were determined by the horizontal deformation-induced frontogenesis.In the frontogenesis function,the terms of horizontal deformation and horizontal convergence together determined the position of the TSL,and the diabatic heating term was conducive to the upward extension of the TSL.

关 键 词:Plateau transverse shear line Structure EVOLUTION Frontogenesis and frontolysis 

分 类 号:P461[天文地球—大气科学及气象学]

 

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