Program and Agenda

Abstract

OCEAN BASIN GEOMETRY AND THE SALINIFICATION OF THE ATLANTIC OCEAN

A coupled atmosphere--sea--ice--ocean model is used in an aqua-planet setting to examine the role of the basin geometry for salinification of the Atlantic Ocean. The geometry has two idealized northern basins and a circumpolar southern ocean. A suite of experiments is described in which the southward extents of the two (grid-point wide) ''continents'' have been varied. When the two basins have identical shapes, the coupled model can attain a symmetric climate state with northern deep water formation in both basins as well as asymmetric states, where the deep water formation occurs only in one of the basins. A difference in the southward extents of the land barriers affects the inter-basin gyre circulation and exchange of heat and salt. Remarkably, when the short ''African'' continent is located equatorward of the zero wind line in the southern hemisphere, the deep water formation becomes uniquely localized to the Atlantic-like basin with the long western boundary. In this case, a southern super-gyre forms and the Atlantic salinification is accomplished primarily by an Agulhas-like inter-basin salt transport. However, if ''Africa'' extends into the band of westerly winds, the direction of the wind-steered inter-basin salt transport tends to be reversed, inducing a preference for sinking in the Pacific-like basin. Thus, the asymmetry induced by the different southward extents of Africa and America by itself is presumably powerful enough to lock the northern sinking to the Atlantic Ocean.

Authors

Nilsson, J., Stockholm University, Sweden, nilsson@misu.su.se

Langen, P. L., Danish Meteorological Institute, Denmark

Ferreira, D., MIT, USA

Marshall, J., USA

Details

Oral presentation

Session #:137
Date: 2/28/2014
Time: 14:30
Location: 312

Presentation is given by student: No