A multiscale analysis of drought and pluvial mechanisms for the southeastern United States
A multiscale analysis of drought and pluvial mechanisms for the southeastern United States
The Southeast (SE) U.S. has experienced several severe droughts over the past 30 years, with the most recent drought during 2006–2008 causing agricultural impacts of $1 billion. However, the mechanisms that lead to droughts over the region and their persistence have been poorly understood due to the region’s humid coastal environment and its complex climate. In this study, we carry out a multiscale analysis of drought mechanisms for the SE U.S. over 1979–2008 using the North American Regional Reanalysis (NARR) to identify conditions associated with drought and contrast with those associated with pluvials. These conditions include land surface drought propagation, land-atmosphere feedbacks, regional moisture sources, persistent atmospheric patterns, and larger-scale oceanic conditions. Typical conditions for SE U.S. droughts (pluvials) are identified as follows: (1) weaker (stronger) southerly meridional fluxes and weaker (stronger) westerly zonal fluxes, (2) strong moisture flux divergence (convergence) by transient eddies, and (3) strong (weak) coupling between the land surface and atmosphere. The NARR demonstrates that historic SE droughts are mainly derived from a combination of a strong North Atlantic subtropical high (NASH) and Icelandic Low (IL) during summer and winter, respectively, which peak 1 month earlier than the onset of the drought. The land surface plays a moderate role in drought occurrence over the SE via recycling of precipitation, and the oceans show an asymmetric influence on droughts and pluvials depending on the season. This study suggests that the NASH and IL can be used as a predictor for SE droughts at 1 month lead despite the overall that it represents an atmospheric forcing.
7348-7367
Kam, Jonghun
2ca1444e-be4f-4250-9fa5-c5b9dca224fe
Sheffield, Justin
dd66575b-a4dc-4190-ad95-df2d6aaaaa6b
Wood, Eric F.
ee59ebb9-367e-48ce-beab-22666be5095d
27 June 2014
Kam, Jonghun
2ca1444e-be4f-4250-9fa5-c5b9dca224fe
Sheffield, Justin
dd66575b-a4dc-4190-ad95-df2d6aaaaa6b
Wood, Eric F.
ee59ebb9-367e-48ce-beab-22666be5095d
Kam, Jonghun, Sheffield, Justin and Wood, Eric F.
(2014)
A multiscale analysis of drought and pluvial mechanisms for the southeastern United States.
Journal of Geophysical Research, 119 (12), .
(doi:10.1002/2014JD021453).
Abstract
The Southeast (SE) U.S. has experienced several severe droughts over the past 30 years, with the most recent drought during 2006–2008 causing agricultural impacts of $1 billion. However, the mechanisms that lead to droughts over the region and their persistence have been poorly understood due to the region’s humid coastal environment and its complex climate. In this study, we carry out a multiscale analysis of drought mechanisms for the SE U.S. over 1979–2008 using the North American Regional Reanalysis (NARR) to identify conditions associated with drought and contrast with those associated with pluvials. These conditions include land surface drought propagation, land-atmosphere feedbacks, regional moisture sources, persistent atmospheric patterns, and larger-scale oceanic conditions. Typical conditions for SE U.S. droughts (pluvials) are identified as follows: (1) weaker (stronger) southerly meridional fluxes and weaker (stronger) westerly zonal fluxes, (2) strong moisture flux divergence (convergence) by transient eddies, and (3) strong (weak) coupling between the land surface and atmosphere. The NARR demonstrates that historic SE droughts are mainly derived from a combination of a strong North Atlantic subtropical high (NASH) and Icelandic Low (IL) during summer and winter, respectively, which peak 1 month earlier than the onset of the drought. The land surface plays a moderate role in drought occurrence over the SE via recycling of precipitation, and the oceans show an asymmetric influence on droughts and pluvials depending on the season. This study suggests that the NASH and IL can be used as a predictor for SE droughts at 1 month lead despite the overall that it represents an atmospheric forcing.
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Published date: 27 June 2014
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Funding Information:
We acknowledge the support of the Princeton TIGRESS high-performance computer center. This work was supported by the NOAA Climate Program Office (NA08OAR4310579, NA11OAR4310097) and the USGS (G11AP20215). The authors are pleased to acknowledge that the work reported on in this paper was substantially performed at the TIGRESS high-performance computer center at Princeton University which is jointly supported by the Princeton Institute for Computational Science and Engineering and the Princeton University Office of Information Technology’s Research Computing department.
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© 2014. American Geophysical Union. All Rights Reserved.
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Local EPrints ID: 480774
URI: http://eprints.soton.ac.uk/id/eprint/480774
ISSN: 0148-0227
PURE UUID: 40b73247-64ce-46b8-84d8-f515b65723f7
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Date deposited: 09 Aug 2023 17:12
Last modified: 18 Mar 2024 03:33
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Author:
Jonghun Kam
Author:
Eric F. Wood
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