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Monotonic decrease of the zonal SST gradient of the equatorial Pacific as a function of CO 2 concentration in CCSM3 and CCSM4
Author(s) -
Yang Jun,
Peltier Wm. Richard,
Hu Yongyun
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd025231
Subject(s) - sea surface temperature , thermocline , climatology , upwelling , environmental science , walker circulation , forcing (mathematics) , atmospheric sciences , climate model , temperature gradient , atmosphere (unit) , geology , climate change , oceanography , meteorology , geography
The west‐east sea surface temperature (SST) gradient in the equatorial Pacific Ocean is a key feature of Earth's climate. How this gradient responds to varying climatic forcing is a challenge to both climate theory and climate modeling. Using the coupled atmosphere‐ocean general circulation models, Community Climate System Model version 3 (CCSM3) and version 4 (CCSM4), we show that the zonal SST gradient is an almost monotonically decreasing function of atmospheric CO 2 concentration ( p CO 2 ) across a wide range from 17.5 to 4576 ppmv. As p CO 2 is increased, the optical depth of clouds over the western and central Pacific increases significantly, reflecting more insolation back to space, suppressing surface warming in this region and thereby reducing the zonal SST gradient. Ocean adjustment to a weakening of surface zonal winds is characterized by relaxations of the equatorial thermocline tilt, zonal surface currents, and ocean upwelling.