Southward Intertropical Convergence Zone Shifts and Implications for an Atmospheric Bipolar Seesaw

• DOI: 10.1175/jcli-d-12-00279.1
• Publication Date: 2013-01-04T23:50:07Z
• Authors: Ivana Cvijanovic; Peter L. Langen; Eigil Kaas; Peter D. Ditlevsen
• Keywords: Intertropical Convergence Zone; Hadley cell; Forcing (mathematics)

Abstract In this study, southward intertropical convergence zone (ITCZ) shifts are investigated in three different scenarios: Northern Hemispheric cooling, Southern warming, and a bipolar seesaw-like forcing that combines the latter two. The experiments demonstrate mutual effects northern- southern-high-latitude forcings exert on tropical precipitation, suggesting time-scale-dependent dominance of northern versus southern forcings. accordance with this, two-phase precipitation suggested, involving fast component dominated by high-northern-latitude slower due to forcing. results may thus be useful for future understanding interpretation high-resolution paleoprecipitation proxies their relation high-latitude records (e.g., ice core data). also show Ocean warming has global impact, affecting both tropics extratropics, as seen ITCZ shift mid- North Atlantic surface temperature wind changes. terms dynamical considerations, circulation response is found nonlinear: atmospheric heat transport Hadley cell anomalies differ significantly (in magnitude) when comparing cooling experiments. These related interhemispheric gradients altered mainly nonlinearities water vapor response. Decomposition top-of-the-atmosphere flux into feedback shows cloud feedbacks tropics, longwave effect governing overall