气候变化领域集成服务门户(CCPortal): Emergent Trends Complicate the Interpretation of the United States Drought Monitor (USDM)

CCPortal

DOI	10.1029/2023AV001070
	Emergent Trends Complicate the Interpretation of the United States Drought Monitor (USDM)
	Li, Zhiying; Smerdon, Jason E.; Seager, Richard; Siegert, Noel; Mankin, Justin S.
发表日期	2024
EISSN	2576-604X
起始页码	5
结束页码	2
卷号	5 期号:2
英文摘要	Effective drought management must be informed by an understanding of whether and how current drought monitoring and assessment practices represent underlying nonstationary climate conditions, either naturally occurring or forced by climate change. Here we investigate the emerging climatology and associated trends in drought classes defined by the United States Drought Monitor (USDM), a weekly product that, since 2000, has been used to inform drought management in the United States. The USDM classifies drought intensity based in part on threshold percentiles in key hydroclimate quantities. Here we assess how those USDM-defined drought threshold percentiles have changed over the last 23 years, examining precipitation, runoff, soil moisture (SM), terrestrial water storage (TWS), vapor pressure deficit (VPD), and near-surface air temperature. We also assess underlying trends in the frequency of drought classifications across the U.S. Our analysis suggests that the frequency of drought class occurrence is exceeding the threshold percentiles defined by the USDM in a number of regions in the United States, particularly in the American West, where the last 23 years have emerged as a prolonged dry period. These trends are also reflected in percentile-based thresholds in precipitation, runoff, SM, TWS, VPD, and temperature. Our results emphasize that while the USDM appears to be accurately reflecting observed nonstationarity in the physical climate, such trends raise critical questions about whether and how drought diagnosis, classification, and monitoring should address long-term intervals of wet and dry periods or trends. Drought classifications in the USDM are based on thresholds of event rarity, usually assessed, in part, by applying such thresholds to drought-relevant variables, like precipitation, runoff, or soil moisture (SM). Global warming and climate variability, however can make these drought class thresholds occur more or less often, generating prolonged wet or dry intervals, altering how often a drought class occurs. Here we document the extent to which climate trends are reflected in drought classifications from the USDM, a weekly expert-generated product used to inform drought management in the U.S. since 2000. Despite the fact that the USDM is based on expert judgment, we show that in various regions across the United States, especially in the American West, USDM drought classes have occurred more frequently than the authors' predefined thresholds suggest they should be, meaning climate changes are apparent in the USDM itself. These changes are also mirrored in the thresholds associated with variables, like runoff and SM. Our findings suggest that the USDM is capturing the changing climate. However, our results also raise important questions about how drought monitoring should reflect longer-term climate changes and what such trends imply about reliably monitoring and informing our management of drought risk. United States Drought Monitor (USDM) drought classifications are trending, with drought classes exceeding the frequency guidelines that define classes Climate variables informing the USDM also show trends, implying that the expert-generated USDM is capturing low-frequency variability These trends raise important questions about reliably monitoring and informing our management of nonstationary drought risks
英文关键词	drought; drought monitoring; climatology; nonstationary climate
语种	英语
WOS研究方向	Geology
WOS类目	Geosciences, Multidisciplinary
WOS记录号	WOS:001207744500001
来源期刊	AGU ADVANCES
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/294941
作者单位	Dartmouth College; Indiana University System; Indiana University Bloomington; Columbia University; Columbia University; Dartmouth College
推荐引用方式 GB/T 7714	Li, Zhiying,Smerdon, Jason E.,Seager, Richard,et al. Emergent Trends Complicate the Interpretation of the United States Drought Monitor (USDM)[J],2024,5(2).
APA	Li, Zhiying,Smerdon, Jason E.,Seager, Richard,Siegert, Noel,&Mankin, Justin S..(2024).Emergent Trends Complicate the Interpretation of the United States Drought Monitor (USDM).AGU ADVANCES,5(2).
MLA	Li, Zhiying,et al."Emergent Trends Complicate the Interpretation of the United States Drought Monitor (USDM)".AGU ADVANCES 5.2(2024).