Publication Abstracts
Cook et al. 2011
, R. Seager, and , 2011: Atmospheric circulation anomalies during two persistent North American droughts: 1932-1939 and 1948-1957. Clim. Dyn., 36, 2339-2355, doi:10.1007/s00382-010-0807-1.
We use an early twentieth century (1908-1958) atmospheric reanalysis, based on assimilation of surface and sea level pressure observations, to contrast the atmospheric circulation during two periods of persistent drought in North America: 1932-1939 (the "Dust Bowl") and 1948-1957. Primary forcing for both droughts is believed to come from sea surface temperature (SST) anomalies in the Atlantic and Pacific ocean basins. For boreal winter (October-March) in the 1950s, a stationary wave pattern originating from the tropical Pacific is present, with positive centers over the north Pacific and north Atlantic ocean basins and a negative center positioned over northwest North America and the tropical/subtropical Pacific. This wave train is absent for the 1930s drought; boreal winter height anomalies are organized much more zonally, with positive heights extending across northern North America. For boreal summer (April-September) during the 1930s, a strong upper level ridge is centered over the Great Plains; this feature is absent during the 1950s and appears to be linked to a weakening of the Great Plains Low Level Jet (GPLLJ). Subsidence anomalies are located over the centers of each drought: over the central Great Plains for the 1930s and in a band extending from the southwest to the southeastern United States for the 1950s. The location and intensity of this subsidence during the 1948-1957 drought is typical for La Nina forcing, but deviates in terms of expected intensity, location, and spatial extent for 1932-1939. Overall, the circulation during the 1950s drought appears consistent with the expected response to the observed SST anomalies; this is not the case for the 1930s, implying some other causal factor may be needed to explain anomalies during the Dust Bowl. The 1930s experienced massive changes to the land surface, including regional scale devegetation from crop failures and intensive wind erosion and dust storms. Incorporation of these land surface factors into a general circulation model greatly improves the simulation of precipitation and subsidence anomalies during this drought, relative to simulations with SST forcing alone. Even with additional forcing from the land surface, however, the model still has difficulty reproducing some of the other circulation anomalies, including substantial weakening of the GPLLJ and strengthening of the upper level ridge during AMJJAS, although this may be due to either weaknesses in the model or uncertainty in the boundary condition estimates. Still, analysis of the circulation anomalies is consistent with the conclusion of an earlier paper (Cook et al. 2009), demonstrating that land degradation factors are necessary (if, perhaps, not sufficient) to explain the anomalous nature of the Dust Bowl drought.
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BibTeX Citation
@article{co07400c,
author={Cook, B. I. and Seager, R. and Miller, R. L.},
title={Atmospheric circulation anomalies during two persistent North American droughts: 1932-1939 and 1948-1957},
year={2011},
journal={Clim. Dyn.},
volume={36},
pages={2339--2355},
doi={10.1007/s00382-010-0807-1},
}
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RIS Citation
TY - JOUR ID - co07400c AU - Cook, B. I. AU - Seager, R. AU - Miller, R. L. PY - 2011 TI - Atmospheric circulation anomalies during two persistent North American droughts: 1932-1939 and 1948-1957 JA - Clim. Dyn. VL - 36 SP - 2339 EP - 2355 DO - 10.1007/s00382-010-0807-1 ER -
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