On the twenty-first-century wet season projections over the Southeastern United States

Regional Environmental Change
By: , and 



This paper reconciles the difference in the projections of the wet season over the Southeastern United States (SEUS) from a global climate model (the Community Climate System Model Version 3 [CCSM3]) and from a regional climate model (the Regional Spectral Model [RSM]) nested in the CCSM3. The CCSM3 projects a dipole in the summer precipitation anomaly: peninsular Florida dries in the future climate, and the remainder of the SEUS region becomes wetter. The RSM forced with CCSM3 projects a universal drying of the SEUS in the late twenty-first century relative to the corresponding twentieth-century summer. The CCSM3 pattern is attributed to the “upped-ante” mechanism, whereby the atmospheric boundary layer moisture required for convection increases in a warm, statically stable global tropical environment. This criterion becomes harder to meet along convective margins, which include peninsular Florida, resulting in its drying. CCSM3 also projects a southwestward expansion of the North Atlantic subtropical high that leads to further stabilizing of the atmosphere above Florida, inhibiting convection. The RSM, because of its high (10-km grid) resolution, simulates diurnal variations in summer rainfall over SEUS reasonably well. The RSM improves upon CCSM3 through the RSM’s depiction of the diurnal variance of precipitation, which according to observations accounts for up to 40 % of total seasonal precipitation variance. In the future climate, the RSM projects a significant reduction in the diurnal variability of convection. The reduction is attributed to large-scale stabilization of the atmosphere in the CCSM3 projections.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title On the twenty-first-century wet season projections over the Southeastern United States
Series title Regional Environmental Change
DOI 10.1007/s10113-013-0477-8
Volume 13
Issue suppl. 1
Year Published 2013
Language English
Publisher Springer
Contributing office(s) Southeast Ecological Science Center
Description 12 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Regional Environmental Change
First page 153
Last page 164
Country United States
State Alabama;Arkansas;Florida;Georgia;Kentucky;Louisiana;Mississippi;Missouri;North Carolina;South Carolina;Tennessee;Virginia
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