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首页> 外文期刊>Climate dynamics >Multiscale control of summertime persistent heavy precipitation events over South China in association with synoptic, intraseasonal, and low-frequency background
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Multiscale control of summertime persistent heavy precipitation events over South China in association with synoptic, intraseasonal, and low-frequency background

机译：与天气，季节内和低频背景相关的华南夏季持续性强降水事件的多尺度控制

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摘要

This study examines persistent and short-lived heavy precipitation events (PHPEs and SHPEs, respectively) in South China during summer (July-September) 1975-2009 in association with large-scale circulation and moisture processes at different timescales. Compared to SHPEs, PHPEs are characterized by long-lasting enhanced convection and cyclonic moisture circulation as well as strengthened moisture convergence over South China. Examination of environmental variables at different timescales suggests that intraseasonal and synoptic components play a deterministic role in regulating the overall changes in convection and moisture convergence, while the low-frequency background state plays only a marginal role. Further analysis of the moisture divergence terms also reveals that the overall changes in moisture divergence during PHPEs and SHPEs stem primarily from variations in the intraseasonal and synoptic wind fields rather than in the humidity fields. Overall, it is found that the location and strength of the intraseasonal oscillation (ISO) and the synoptic disturbances play a decisive role in controlling the severity and duration of rainfall events over South China. The synchronization and persistence of the enhanced convection and moisture circulation of the ISO and synoptic disturbances jointly contribute to prolonged heavy precipitation over South China, while the weakening and asynchrony of the associated convection and moisture circulation at different timescales result in rainfall events of weaker intensity and shorter duration.
机译：这项研究调查了1975-2009年夏季（7月至9月）华南地区持续的和短暂的强降水事件（分别为PHPE和SHPE），以及不同时间尺度的大规模循环和水分过程。与SHPE相比，PHPE的特点是对华南地区的对流和旋风湿气循环持续时间长，并且收敛性增强。在不同时间尺度上对环境变量的研究表明，季节内和天气要素在调节对流和水分收敛的总体变化中起决定性作用，而低频本底状态仅起边际作用。对水分散度项的进一步分析还表明，PHPE和SHPE期间水分散度的总体变化主要源于季节内和天气风场的变化，而不是湿度场的变化。总体而言，发现季节内振荡（ISO）的位置和强度以及天气干扰在控制华南地区降雨事件的严重性和持续时间方面起着决定性的作用。 ISO对流和水分循环增强以及天气干扰的同步和持续性共同导致了华南地区长时间的强降水，而不同时间尺度上相关对流和水分循环的减弱和不同步导致降雨事件强度和强度减弱。持续时间短。

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