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屈顶, 李跃清, 李娟, 等. 2023. 不同类型九龙涡的水汽输送与热力结构特征的对比分析[J]. 大气科学, 47(5): 1481−1494. doi: 10.3878/j.issn.1006-9895.2208.21202
引用本文: 屈顶, 李跃清, 李娟, 等. 2023. 不同类型九龙涡的水汽输送与热力结构特征的对比分析[J]. 大气科学, 47(5): 1481−1494. doi: 10.3878/j.issn.1006-9895.2208.21202
QU Ding, LI Yueqing, LI Juan, et al. 2023. Comparative Analysis of Water Vapor Transport and Thermodynamic Characteristics of Different Types of Jiulong Vortices Found in Southwest China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(5): 1481−1494. doi: 10.3878/j.issn.1006-9895.2208.21202
Citation: QU Ding, LI Yueqing, LI Juan, et al. 2023. Comparative Analysis of Water Vapor Transport and Thermodynamic Characteristics of Different Types of Jiulong Vortices Found in Southwest China [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(5): 1481−1494. doi: 10.3878/j.issn.1006-9895.2208.21202

不同类型九龙涡的水汽输送与热力结构特征的对比分析

Comparative Analysis of Water Vapor Transport and Thermodynamic Characteristics of Different Types of Jiulong Vortices Found in Southwest China

  • 摘要: 应用1989~2018年6~8月ERA-interim再分析资料,在西南涡之九龙涡新定义的基础上,通过观测、诊断、合成分析,深入研究了川西高原涡源子区域1和子区域2源地型、偏东型、东北型、偏南型九龙涡的水汽输送、热力特征及其变化。结果表明:(1)夏季九龙涡水汽主要来源于印度洋,受多尺度系统协同作用影响,源地型、偏东型、东北型生成区主要为西南水汽输送,偏南型则为西北水汽输送。伴随九龙涡生成,生成区水汽辐合逐渐加强,结束时次,移动型九龙涡在对应的移动方向下游具有异常的水汽通量辐合。(2)九龙涡涡区主要为热量消耗,其中源地型九龙涡热量消耗较大且无充足补给成为其消亡的原因之一,初生时次低层(高层)水汽消耗(增加),但发展后均为消耗;子区域1(子区域2)下垫面、环流影响复杂(简单),视热源、视水汽汇项垂直分布多样(单一),具有多个(一个)极值中心;辐射冷却和小尺度涡旋垂直输送可使视热源项中心高于视水汽汇项中心。(3)九龙涡的视热源、视水汽汇的大值区主要位于低涡东北部,且视水汽汇强于视热源,分别对应低涡强对流区和强夜发性;移动型的视热源和视水汽汇分布及变化一般都强于源地型,其中,子区域1的东北型、偏南型始终保持较强分布,子区域2的移动型和源地型初生时次差异不大,结束时次东北型显著增强。(4)源地型低涡的消亡最先表现为视水汽汇在低涡外围的减弱,而偏东型、东北型则在移动方向扩展、增强,形成视热源、水汽汇大值区,分别预示着九龙涡的减弱消亡和发展移动;偏南型西南侧有一热源大值系统,可能成为其偏南移出的外强迫因素。综上,区域和环境水汽、大气热力条件等异常变化与九龙涡演变密切相关,两者可能是九龙涡生成、消亡、发展、移动的重要原因。

     

    Abstract: The characteristics and changes of water vapor transport and the thermodynamic characteristics of the local, eastward, northeastward, and southward types from various vortex sources (subregions 1 and 2) in the western Sichuan Plateau are thoroughly examined through observation and diagnosis. The ECMWF Reanalysis-interim data from June to August of 1989–2018, based on the new definition of the Jiulong vortex (JLV) of the Southwest China vortex, were examined to conduct this investigation. The results demonstrate the following: (1) The water vapor primarily arises from the Indian Ocean during summer. Under the action of multiple systems, a southwestward transport of water vapor is observed in the local, eastward, and northeastward types, whereas a northwestward transport of water vapor is observed in the southward type. The convergence of water vapor in the generation region is strengthened via the formation of the JLV, at the end of which the moving (eastward, northeastward, southward) type exhibits an anomalous convergence of water vapor flux downstream of the corresponding moving direction. (2) The JLV region primarily involves heat consumption. The local type may not have sufficient supplies and requires a substantial amount of heat, which may be one of the factors leading to its demise. Water vapor is consumed at the lower level and grows at the higher level at birth, but after development, it is consumed throughout the layer. Because of the complex (simple) effect of the underlying surface and circulation associated with subregion 1 (subregion 2), the apparent heat source and apparent water vapor sinks exhibit diverse (single) vertical distributions, with multiple (one) extreme centers. the polar center of the apparent heat source is higher than the polar center of the apparent water vapor sink due to radiative cooling and vertical transport of small-scale vortex. (3) The large value area of the apparent heat source and apparent water vapor sink of JLV are mainly located in the northeast of the low vortex, which corresponds to the strong convection area of the JLV, and the apparent water vapor sink is stronger than the apparent heat source, which corresponds to the strong nocturnal. The intensity of the distribution and variation of the apparent heat source and apparent water vapor sink of the moving type are typically stronger than those of the local type. Among them, the northeastward type and southward type of subregion 1 always maintain a strong distribution of the apparent heat source and apparent water vapor sink , which is in considerable contrast to that observed in local and eastward types. In Subregion 2, the moving type and the local type differ slightly at birth, and after development the northeastward type is greatly improved. (4) The demise of the local type is first manifested as the weakening of the apparent water vapor sink at the periphery of the low vortex, while the eastward and northeastward types expand and strengthen in the direction of movement. There is a large heat source system on the southwest side of the southward type, which may be an external forcing factor for its southward migration. In conclusion, the abnormal changes in regional and environmental water vapor and atmospheric thermodynamic conditions are strongly associated with the evolution of the JLV; such changes could be the main reasons for the formation, extinction, development, and movement of the JLV.

     

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