TY - JOUR
T1 - A multiscale analysis of drought and pluvial mechanisms for the southeastern United States
AU - Kam, Jonghun
AU - Sheffield, Justin
AU - Wood, Eric F.
N1 - 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.
Publisher Copyright:
© 2014. American Geophysical Union. All Rights Reserved.
PY - 2014/6/27
Y1 - 2014/6/27
N2 - 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.
AB - 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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U2 - 10.1002/2014JD021453
DO - 10.1002/2014JD021453
M3 - Article
AN - SCOPUS:84904767645
SN - 0148-0227
VL - 119
SP - 7348
EP - 7367
JO - Journal of Geophysical Research: Oceans
JF - Journal of Geophysical Research: Oceans
IS - 12
ER -