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Underlying causes of Eurasian midcontinental aridity in simulations of mid‐Holocene climate
Author(s) -
Bartlein Patrick J.,
Harrison Sandy P.,
Izumi Kenji
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl074476
Subject(s) - climatology , precipitation , holocene , arid , environmental science , climate model , moisture , atmospheric circulation , flux (metallurgy) , climate change , evaporation , atmospheric sciences , zonal flow (plasma) , geology , geography , oceanography , meteorology , plasma , physics , quantum mechanics , tokamak , paleontology , materials science , metallurgy
Climate model simulations uniformly show drier and warmer summers in the Eurasian midcontinent during the mid‐Holocene, which is not consistent with paleoenvironmental observations. The simulated climate results from a reduction in the zonal temperature gradient, which weakens westerly flow and reduces moisture flux and precipitation in the midcontinent. As a result, sensible heating is favored over evaporation and latent heating, resulting in substantial surface‐driven atmospheric warming. Thus, the discrepancy with the paleoenvironmental evidence arises initially from a problem in the simulated circulation and is exacerbated by feedback from the land surface. This region is also drier and warmer than indicated by observations in the preindustrial control simulations, and this bias arises in the same way: zonal flow and hence moisture flux into the midcontinent are too weak, and feedback from the land surface results in surface‐driven warming. These analyses suggest the need to improve those aspects of climate models that affect the strength of westerly circulation.