Drier tropical and subtropical Southern Hemisphere in the mid-Pliocene Warm Period
ORCID: https://orcid.org/0000-0003-2089-733X, Otto-Bliesner, Bette L., Peltier, W. Richard, Stepanek, Christian
ORCID: https://orcid.org/0000-0002-3912-6271, Tindall, Julia, Tan, Ning, Zhang, Qiong and Zhang, Zhongshi
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Thermodynamic arguments imply that global mean rainfall increases in a warmer atmosphere; however, dynamical effects may result in more significant diversity of regional precipitation change. Here we investigate rainfall changes in the mid-Pliocene Warm Period (~ 3 Ma), a time when temperatures were 2–3ºC warmer than the pre-industrial era, using output from the Pliocene Model Intercomparison Projects phases 1 and 2 and sensitivity climate model experiments. In the Mid-Pliocene simulations, the higher rates of warming in the northern hemisphere create an interhemispheric temperature gradient that enhances the southward cross-equatorial energy flux by up to 48%. This intensified energy flux reorganizes the atmospheric circulation leading to a northward shift of the Inter-Tropical Convergence Zone and a weakened and poleward displaced Southern Hemisphere Subtropical Convergences Zones. These changes result in drier-than-normal Southern Hemisphere tropics and subtropics. The evaluation of the mid-Pliocene adds a constraint to possible future warmer scenarios associated with differing rates of warming between hemispheres.
ORCID: https://orcid.org/0000-0003-2089-733X, Otto-Bliesner, Bette L., Peltier, W. Richard, Stepanek, Christian
ORCID: https://orcid.org/0000-0002-3912-6271, Tindall, Julia, Tan, Ning, Zhang, Qiong and Zhang, Zhongshi
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