气候变化领域集成服务门户(CCPortal): Upper-Tropospheric Troughs and North American Monsoon Rainfall in a Long-Term Track Dataset

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DOI	10.1029/2021JD034541
	Upper-Tropospheric Troughs and North American Monsoon Rainfall in a Long-Term Track Dataset
	Igel M.R.; Ullrich P.A.; Boos W.R.
发表日期	2021
ISSN	2169-897X
卷号	126 期号:20
英文摘要	The North American monsoon is frequently affected by transient, propagating upper tropospheric vorticity anomalies. Sometimes called Tropical Upper-Tropospheric Troughs (TUTTs), these features have been claimed to episodically enhance monsoon rainfall. Here, we track long-lived TUTTs in 40 years of reanalysis data, producing composites and case studies from 340 TUTTs which last, on average, 7 days as they move westward across the North American monsoon region. TUTTs are thought to form from midlatitude Rossby wave breaking; case studies from our dataset support this theory. TUTTs move westward within the easterly upper-level flow in which they are embedded. In vortex-centered composites along the full tracks of long-lived TUTTs, we find no detectable increase in rainfall within the main TUTT circulation. Instead, negative precipitation anomalies lie within about 500 km of the TUTT center. Quasi-geostrophic ascent occurs in the southeast quadrant of TUTTs but is confined to the upper troposphere and does not appear to interact with precipitation. Positive anomalies of ascent and rainfall occur south and southeast of TUTTs but lie outside the main TUTT vortex, perhaps indicating concurrent variations in nearby climatological precipitation maxima. In contrast with previous case studies and subjective analyses that showed TUTTs enhance precipitation in parts of northwestern Mexico, our composites along the tracks of long-lived TUTTs portray these systems, to first order, as strong vorticity anomalies trapped in the upper troposphere that interact only weakly and indirectly with precipitation. © 2021. American Geophysical Union. All Rights Reserved.
来源期刊	Journal of Geophysical Research: Atmospheres
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/236935
作者单位	Department of Land, Air and Water Resources, University of California Davis, Davis, CA, United States; Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States; Department of Earth and Planetary Science, University of California Berkeley, Berkeley, CA, United States
推荐引用方式 GB/T 7714	Igel M.R.,Ullrich P.A.,Boos W.R.. Upper-Tropospheric Troughs and North American Monsoon Rainfall in a Long-Term Track Dataset[J],2021,126(20).
APA	Igel M.R.,Ullrich P.A.,&Boos W.R..(2021).Upper-Tropospheric Troughs and North American Monsoon Rainfall in a Long-Term Track Dataset.Journal of Geophysical Research: Atmospheres,126(20).
MLA	Igel M.R.,et al."Upper-Tropospheric Troughs and North American Monsoon Rainfall in a Long-Term Track Dataset".Journal of Geophysical Research: Atmospheres 126.20(2021).