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  • Evaluating the large-scale hydrological cycle response within the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) ensemble
Title: Evaluating the large-scale hydrological cycle response within the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) ensemble
Abstract. The mid-Pliocene (∼3 Ma) is one of the most recent warm periods with high CO2 concentrations in the atmosphere and resulting high temperatures, and it 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 increasedatmospheric moisture content within the mid-Pliocene ensemble (due to thethermodynamic effect) results in wetter conditions over the deep tropics,i.e., the Pacific intertropical convergence zone (ITCZ) and the MaritimeContinent, and drier conditions over the subtropics. Note that the dynamiceffect plays a more important role than the thermodynamic effect in regionalprecipitation minus evaporation (PmE) changes (i.e., northward ITCZ shiftand wetter northern Indian Ocean). The thermodynamic effect isoffset to some extent by a dynamic effect involving a northward shift of the Hadleycirculation that dries the deep tropics and moistens the subtropics in theNorthern Hemisphere (i.e., the subtropical Pacific). From the perspective ofEarth's energy budget, the enhanced southward cross-equatorial atmospherictransport (0.22 PW), induced by the hemispheric asymmetries of theatmospheric energy, favors an approximately 1∘ northward shift ofthe ITCZ. The shift of the ITCZ reorganizes atmospheric circulation,favoring a northward shift of the Hadley circulation. In addition, theWalker circulation consistently shifts westward within PlioMIP2 models,leading to wetter conditions over the northern Indian Ocean. The PlioMIP2ensemble highlights that an imbalance of interhemispheric atmospheric energyduring the mid-Pliocene could have led to changes in the dynamic effect,offsetting the thermodynamic effect and, hence, altering mid-Pliocenehydroclimate.  more » « less
Award ID(s):
1903650
PAR ID:
10345279
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; ; ; ; ; ; ; ; ; « less
Date Published:
Journal Name:
Climate of the Past
Volume:
17
Issue:
6
ISSN:
1814-9332
Page Range / eLocation ID:
2537 to 2558
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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