Main energy paths and energy cascade processes of the two types of persistent heavy rainfall events over the Yangtze River–Huaihe River Basin

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• 作者：Yuanchun Zhang ; Jianhua Sun ; Shenming Fu
• 关键词：persistent heavy rainfall event ; energy cascade process ; large ; scale background circulation ; precipitation ; related eddy flow
• 刊名：Advances in Atmospheric Sciences
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：34
• 期：2
• 页码：129-143
• 全文大小：
• 刊物主题：Atmospheric Sciences; Meteorology; Geophysics/Geodesy;
• 出版者：Science Press
• ISSN：1861-9533
• 卷排序：34

文摘

Two types of persistent heavy rainfall events (PHREs) over the Yangtze River–Huaihe River Basin were determined in a recent statistical study: type A, whose precipitation is mainly located to the south of the Yangtze River; and type B, whose precipitation is mainly located to the north of the river. The present study investigated these two PHRE types using a newly derived set of energy equations to show the scale interaction and main energy paths contributing to the persistence of the precipitation. The main results were as follows. The available potential energy (APE) and kinetic energy (KE) associated with both PHRE types generally increased upward in the troposphere, with the energy of the type-A PHREs stronger than that of the type-B PHREs (except for in the middle troposphere). There were two main common and universal energy paths of the two PHRE types: (1) the baroclinic energy conversion from APE to KE was the dominant energy source for the evolution of large-scale background circulations; and (2) the downscaled energy cascade processes of KE and APE were vital for sustaining the eddy flow, which directly caused the PHREs. The significant differences between the two PHRE types mainly appeared in the lower troposphere, where the baroclinic energy conversion associated with the eddy flow in type-A PHREs was from KE to APE, which reduced the intensity of the precipitation-related eddy flow; whereas, the conversion in type-B PHREs was from APE to KE, which enhanced the eddy flow.