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A model intercomparison of the tropical precipitation response to a CO 2 doubling in aquaplanet simulations
Author(s) -
Seo Jeongbin,
Kang Sarah M.,
Merlis Timothy M.
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 - 10.1002/2016gl072347
Subject(s) - intertropical convergence zone , equator , hadley cell , climatology , atmospheric sciences , environmental science , precipitation , walker circulation , convergence zone , energetics , latitude , climate model , tropical wave , convection , sea surface temperature , climate change , geology , physics , general circulation model , meteorology , tropical cyclone , oceanography , thermodynamics , geodesy
In the present‐day climate, the mean Intertropical Convergence Zone (ITCZ) is north of the equator. We investigate changes in the ITCZ latitude under global warming, using multiple atmospheric models coupled to an aquaplanet slab ocean. The reference climate, with a warmer north from prescribed ocean heating, is perturbed by doubling CO 2 . Most models exhibit a northward ITCZ shift, but the shift cannot be accounted for by the response of energy flux equator where the atmospheric energy transport ( F A ) vanishes. The energetics of the simulated circulation shifts are subtle: changes in the efficiency with which the Hadley circulation transports energy, the total gross moist stability (Δ m ), dominate over mass flux changes in determining δ F A . Even when δ F A ≈ 0, the ITCZ can shift significantly due to changes in Δ m , which have often been neglected previously. The dependence of ITCZ responses on δΔ m calls for improved understanding of the physics determining the tropical Δ m .