气候变化领域集成服务门户(CCPortal): Intraseasonal variation of the summer rainfall over the Southeastern United States

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DOI	10.1007/s00382-018-4345-6
	Intraseasonal variation of the summer rainfall over the Southeastern United States
	Wei W.; Li W.; Deng Y.; Yang S.
发表日期	2019
ISSN	0930-7575
起始页码	1171
结束页码	1183
卷号	53 期号:2020-01-02
英文摘要	This study characterizes the intraseasonal variability (ISV) in the Southeastern United States (SE US) rainfall in boreal summer and delineates the associated dynamical processes featuring three-way interactions among the SE US rainfall, the central US low-level jet (LLJ), and the North Atlantic subtropical high (NASH). The analysis reveals that the ISV of the SE summer rainfall peaks at the 10‒20-day timescales. The physical mechanisms for the three-way interactions on the 10‒20-day timescales are proposed. When the NASH attains a minimum strength, the reduced size of the NASH is accompanied with an eastward retreat of the western ridge of the NASH, leading to a decrease in the zonal pressure gradient and consequently a weakening of the LLJ 1 day after. The weakened LLJ and the eastward-shifted NASH western ridge induces anomalous cyclonic circulation over the SE US, moves preferred regions of moisture convergence from central US to the SE US, and 3 days later the SE US rainfall attains its maximum strength. The excessive latent heating associated with the enhanced SE US rainfall excites an anomalous anticyclone northeast of the rainfall region, resulting in an increase in the NASH intensity that peaks 2 days after the maximum SE US rainfall. The NASH subsequently expands with its western ridge moving westward, zonal pressure gradient restored, and LLJ strength recovered. An anomalous anticyclone then emerges over the SE US and suppresses rainfall, marking the shift from an intraseasonal wet phase to dry phase in this region. A more rigorous proof of these causalities demand carefully designed numerical experiments and further statistical analysis in future. Our results suggest that improved prediction of SE US summer rainfall across intraseasonal scales depends critically on the model representation of the three-way coupling among the NASH, the central US LLJ, and the SE US rainfall. © 2018, The Author(s).
英文关键词	Intraseasonal variation; Low-level jet; North Atlantic subtropical high; Southeastern United States summer rainfall
语种	英语
来源期刊	Climate Dynamics
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/146224
作者单位	School of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, China; Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, Durham, NC 27708-0328, United States; Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou, China; School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA, United States
推荐引用方式 GB/T 7714	Wei W.,Li W.,Deng Y.,et al. Intraseasonal variation of the summer rainfall over the Southeastern United States[J],2019,53(2020-01-02).
APA	Wei W.,Li W.,Deng Y.,&Yang S..(2019).Intraseasonal variation of the summer rainfall over the Southeastern United States.Climate Dynamics,53(2020-01-02).
MLA	Wei W.,et al."Intraseasonal variation of the summer rainfall over the Southeastern United States".Climate Dynamics 53.2020-01-02(2019).