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Testing Latitudinally Dependent Explanations of the Circulation Response to Increased CO 2 Using Aquaplanet Models
Author(s) -
Shaw Tiffany A.,
Tan Zhihong
Publication year - 2018
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 - 10.1029/2018gl078974
Subject(s) - hadley cell , middle latitudes , climatology , walker circulation , atmospheric circulation , atmospheric sciences , latitude , extratropical cyclone , circulation (fluid dynamics) , environmental science , equator , general circulation model , subtropics , geology , climate change , oceanography , sea surface temperature , physics , ecology , biology , geodesy , thermodynamics
The atmospheric circulation exhibits robust responses to increased CO 2 that emerge across the climate model hierarchy. Existing theoretical explanations of the circulation response can be grouped according to latitude. Here we test latitudinally dependent explanations of the circulation response to increased CO 2 using slab ocean aquaplanet models with latitudinally dependent CO 2 concentration. Quadrupling CO 2 in the tropics (0–20°) accounts for the strengthening and upward shift of the subtropical jet but does not account for the poleward shift of the Hadley cell edge or extratropical circulation. The tropical response is dominated by regions of descent. When CO 2 is quadrupled in high latitudes (60–90°), there is a negligible circulation response. The response to latitudinally dependent increased CO 2 is mostly linear and increased CO 2 in the midlatitudes (20–60°) dominates. Within the midlatitudes, the subtropics (20–40°) dominate. Thus, story lines explaining the circulation shift in response to increased CO 2 should focus on the thermodynamic response in the subtropics.