Wu Yutian author Columbia University. Applied Physics and Applied Mathematics Seager Richard author Columbia University. Lamont-Doherty Earth Observatory Ting Mingfang author Columbia University. Lamont-Doherty Earth Observatory Columbia University. Earth and Environmental Sciences Naik Naomi H. author Columbia University. Lamont-Doherty Earth Observatory Shaw Tiffany Ann author Columbia University. Lamont-Doherty Earth Observatory Columbia University. Lamont-Doherty Earth Observatory originator text Articles 2011 manuscript version English This study aims to understand the dynamical mechanisms driving the changes in the general circulation of the atmosphere due to increased carbon dioxide (CO2) by looking into the transient step-by-step adjustment of the circulation. The transient atmospheric adjustment is examined using the National Center for Atmospheric Research Community Atmospheric Model Version 3 coupled to a slab ocean model and the CO2 concentration in the atmosphere is uniformly and instantaneously doubled. The thermal structure and circulation response is well established after one year of integration with the magnitudes gradually increasing afterwards towards quasi-equilibrium. Tropical upper tropospheric warming occurs in the first month. The expansion of the warming in the middle and upper troposphere to the subtropics occurs later and is found to be primarily dynamically-driven due to the intensification of transient eddy momentum flux convergence and resulting anomalous descending motion in this region. The poleward displacement of the midlatitude tropospheric jet streams occurs together with the change in eddy momentum flux convergence but only after the intensification of the subpolar westerlies in the stratosphere. The results demonstrate the importance of the tropospheric eddies in setting up the extratropical tropospheric response to global warming. Environmental science http://hdl.handle.net/10022/AC:P:10556 NNC NNC 2011-06-20 11:55:11 -0400 2011-06-20 12:08:28 -0400 4503 eng