Affiliation:
1. Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China
2. College of Earth and Planetary Sciences University of Chinese Academy of Sciences Beijing China
3. National Institute of Natural Hazards Ministry of Emergency Management of China Beijing China
Abstract
AbstractWe investigate global and regional changes in the intertropical convergence zone (ITCZ) position, width, and intensity during the last glacial maximum (LGM) relative to the preindustrial period using multiple simulations from Phases 3 and 4 of the Paleoclimate Modelling Intercomparison Project (PMIP3/4). On annual scale, most models show that LGM tropical precipitation decreases, and the deficit in the Northern Hemisphere is larger than that in the Southern Hemisphere, resulting in the southward shift, narrowing, and weakening of the ITCZ at the global scale. The arithmetic mean of 13 models shows that the global zonal mean ITCZ shifts southward by 0.85° (1σ = 0.86°), narrows by 1.05° (1σ = 1.33°), and weakens by 7% (1σ = 4%) during the LGM. Regionally, position and intensity changes are larger in the central and eastern Pacific, while width changes are most obvious in the Indian Ocean–western Pacific. Precipitation changes in the central and eastern Pacific and Atlantic oceans are dominated by the dynamic term. In the Indian Ocean–western Pacific, the thermodynamic term is the main cause for precipitation changes within 10°S–10°N, while the dynamic term plays a leading role at other tropical latitudes. Seasonally, the September–October–November and June–July–August mainly contribute to the annual ITCZ position, width, and intensity changes globally and in most regions. The convergence factor dominates both the dynamic and thermodynamic terms annually and seasonally. The model results are compatible with the existing site reconstructions on the southward shift of the LGM ITCZ.
Publisher
American Geophysical Union (AGU)
Subject
Space and Planetary Science,Earth and Planetary Sciences (miscellaneous),Atmospheric Science,Geophysics
Cited by
2 articles.
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