Evaluating the large-scale hydrological cycle response within the PlioMIP2 ensemble
- 1College of Oceanography, Hohai University, Nanjing, China
- 2Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
- 3Department of Geosciences, College of Liberal Arts and Sciences, University of Connecticut, CT 06269, USA
- 4School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds, West Yorkshire, UK
- 5Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO 80305, USA
- 6Department of Atmospheric Science, School of Environmental Studies, China University of Geosciences, Wuhan, China
- 7NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway
- 8Department of Earth Science, University of Bergen, Bjerknes Centre for Climate Research, Bergen, Norway
- 9Centre for Earth Evolution and Dynamics, University of Oslo, Oslo, Norway
- 10Institute for Environmental Physics, University of Bremen, Bremen, Germany
- 11Alfred Wegener Institute-Helmholtz-Zentrum für Polar und Meeresforschung, Bremerhaven, Germany
- 12Center for Climate Systems Research, Columbia University, New York, USA
- 13NASA Goddard Institute for Space Studies, New York, USA
- 14Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
- 15Laboratoire des Sciences du Climat et de l’Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Universit Paris-Saclay, Gif-sur-Yvette, France
- 16Institute for Marine and Atmospheric research Utrecht (IMAU), Department of Physics, Utrecht University, Utrecht, The Netherlands
- 17Department of Physics, University of Toronto, Toronto, Ontario, Canada
- 18School of Geographical Sciences, University of Bristol, Bristol, UK
- 19NCAS-Climate, Department of Meteorology, University of Reading, Reading, UK
- 20School of Environmental Science and Engineering, Yancheng Institute of Technology, Yancheng, China
- 21Key Laboratory for Virtual Geographic Environment, Ministry of Education; State Key Laboratory Cultivation Base of Geographical Environment Evolution of Jiangsu Province; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application; School of Geography, Nanjing Normal University, Nanjing, China
- 22Center for Ocean-Land-Atmosphere Studies, George Mason University, Fairfax, Virginia, USA
Abstract. The mid-Pliocene (~ 3 million years ago) is one of the most recent warm periods with high CO2 concentrations in the atmosphere and resulting high temperatures and is often cited as an analog for near-term future climate change. Here, we apply a moisture budget analysis to investigate the response of the large-scale hydrological cycle at low latitudes within a 13-model ensemble from the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2). The results show that increased atmospheric moisture content within the mid-Pliocene ensemble (the thermodynamic effect) results in wetter conditions over the deep tropics, i.e., the Pacific intertropical convergence zone (ITCZ) and the Maritime Continent, and drier conditions over the subtropics. The thermodynamic effect is to some extent offset by a dynamic effect involving a northward shift of the Hadley circulation that dries the deep tropics and moistens the subtropics in the Northern Hemisphere (i.e., the subtropical Pacific). From the perspective of Earth’s energy budget, the enhanced southward cross-equatorial atmospheric transport (0.22 PW), induced by the hemispheric asymmetries of the atmospheric energy, favors an approximately 1° northward shift of the ITCZ. The shift of the ITCZ reorganizes atmospheric circulation, favoring a northward shift of the Hadley circulation. In addition, the Walker circulation consistently shifts westward within PlioMIP2 models, leading to wetter conditions over the northern Indian Ocean. The PlioMIP2 ensemble highlights that an imbalance of interhemispheric atmospheric energy during the mid-Pliocene could have led to changes in the dynamic effect, offsetting the thermodynamic effect and hence altering mid-Pliocene hydroclimate cycling.
Zixuan Han et al.
Zixuan Han et al.
Zixuan Han et al.
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