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Vegetation stress as a feedback mechanism in midlatitude droughtAn atmospheric general circulation model with land surface properties represented by the Simplified Simple Biosphere Model is used to investigate the effect of soil moisture and vegetation stress on drought in the mid-latitudes. An idealized land-sea distribution with simple topography is used to remove as many external sources of climate variation as possible. The land consists of a single, flat, rectangular continent covered with prairie vegetation and centered on 44 deg N of an aqua planet. A control integration of 4 years is performed, and several sets of seasonal anomaly integrations are made to test the sensitivity of seasonal climate to low initial (1 April) soil moisture and dormant vegetation like what would occur during a severe drought. It is found that the inclusion of dormant vegetation during the spring and early summer greatly reduces evapotranspiration by eliminating transpiration. This affects local climate more strongly as summer progresses. Low initial soil moisture, combined with dormant vegetation, leads to a severe drought. The reduction in precipitation is much greater in magnitude than that due to low soil moisture alone, and greater than the sum of the effects computed separately. Although the short-term drought is more severe, the dormancy of the vegetation prevents further depletion of moisture in the root zone of the soil, so soil moisture begins to rebound toward the middle of summer.
Document ID
19950033754
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Dirmeyer, Paul A.
(Center for Ocean-Land-Atmosphere Studies, Calverton, MD United States)
Date Acquired
August 16, 2013
Publication Date
October 1, 1994
Publication Information
Publication: Journal of Climate
Volume: 7
Issue: 10
ISSN: 0894-8755
Subject Category
Meteorology And Climatology
Accession Number
95A65353
Funding Number(s)
CONTRACT_GRANT: NAGW-2661
CONTRACT_GRANT: NAGW-1269
CONTRACT_GRANT: NSF ATM-90-19296
Distribution Limits
Public
Copyright
Other

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