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申冬冬, 冉令坤, 杨帅, 等. 2023. 新疆山地锋面暴雨的锋生分析[J]. 大气科学, 47(6): 1843−1862. doi: 10.3878/j.issn.1006-9895.2203.21252
引用本文: 申冬冬, 冉令坤, 杨帅, 等. 2023. 新疆山地锋面暴雨的锋生分析[J]. 大气科学, 47(6): 1843−1862. doi: 10.3878/j.issn.1006-9895.2203.21252
SHEN Dongdong, RAN Lingkun, YANG Shuai, et al. 2023. Frontogenetic Analyses of the Topographic Frontal Rainstorm in Xinjiang [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(6): 1843−1862. doi: 10.3878/j.issn.1006-9895.2203.21252
Citation: SHEN Dongdong, RAN Lingkun, YANG Shuai, et al. 2023. Frontogenetic Analyses of the Topographic Frontal Rainstorm in Xinjiang [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 47(6): 1843−1862. doi: 10.3878/j.issn.1006-9895.2203.21252

新疆山地锋面暴雨的锋生分析

Frontogenetic Analyses of the Topographic Frontal Rainstorm in Xinjiang

  • 摘要: 本研究充分考虑新疆复杂地形效应及锋面暴雨区湿大气的凝结潜热加热:(1)发展了地形追随坐标下基于位温、相当位温、广义位温的热力学锋生函数和基于变形场的动力学锋生函数,阐述地形追随坐标下的锋生函数在研究复杂地形锋面过程的优势;(2)从锋生过程更本质的温湿度梯度增大过程角度讨论四种锋生的优劣势,发现广义位温锋生和变形锋生与降水过程有更好的对应关系;(3)借助新疆一次北天山到南天山的移动型锋面降水的WRF数值模拟,对广义位温锋生函数和变形锋生函数的主要强迫和对降水的作用进行诊断分析,结论表明动力学锋生在降水触发和减弱阶段有重要作用,由涡度散度变形的能量转换引起,热力学锋生主要作用于降水发展阶段,潜热加热是其主要强迫。实际应用中,近地层至中低对流层两类锋生的重叠区可指示未来降水移动方向。

     

    Abstract: In this study, considering the complex topographic effect in Xinjiang and the condensation latent heat heating of the moist atmosphere near the frontal rainstorm area, (1) we obtain the thermodynamic frontogenesis functions under terrain-following coordinates based on the potential temperature, equivalent potential temperature, and generalized potential temperature, and the dynamic frontogenesis function driven by the deformation field. The advantages of frontogenesis functions in terrain-following coordinates while studying frontal processes in complex topographical regions are expounded. (2) We describe the advantages and disadvantages of the four frontogeneses from the perspective of the temperature and humidity gradient increase, which is the more crucial process during frontogenesis, and discover that the generalized potential temperature and deformation frontogenesis have a better correspondence with the precipitation process. Furthermore, (3) we conduct a numerical simulation of a frontal precipitation event, which propagates from north to south of Tianshan in Xinjiang, by using the WRF model and perform the analysis of the main forcing of the thermodynamic and dynamic frontogenesis functions, as well as their effect during the rainfall. The findings imply that dynamic frontogenesis plays an essential role in the precipitation triggering and weakening stage and is caused by energy conversion between vorticity, divergence, and deformation. Thermodynamic frontogenesis primarily acts on the precipitation development stage, and latent heating is the main force. In practical applications, the overlapping region of two frontogenesis functions in the near-surface layer and mid-lower troposphere could show the direction of future precipitation propagation.

     

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