Water mass transformation and the North Atlantic Current in three multicentury climate model simulations
Article first published online: 2 NOV 2012
©2012. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Oceans (1978–2012)
Volume 117, Issue C11, November 2012
How to Cite
2012), Water mass transformation and the North Atlantic Current in three multicentury climate model simulations, J. Geophys. Res., 117, C11001, doi:10.1029/2012JC008021., , , , and (
- Issue published online: 2 NOV 2012
- Article first published online: 2 NOV 2012
- Manuscript Accepted: 17 SEP 2012
- Manuscript Revised: 15 SEP 2012
- Manuscript Received: 6 MAR 2012
- North Atlantic Current;
- climate models;
- water mass transformation
 The warm and saline Subtropical Water carried by the North Atlantic Current undergoes substantial transformation on its way to higher latitudes, predominantly from oceanic heat loss to the atmosphere. The geographical distribution of the surface forced water mass transformation is assessed in multicentury climate simulations from three different climate models (BCM, IPSLCM4, and MPI-M ESM), with a particular focus on the eastern subpolar North Atlantic Ocean. A diagnosis, originally introduced by Walin (1982), estimates the surface water mass transformation from buoyancy forcing. While the depth structure of the Atlantic Meridional Overturning Circulation (AMOC) is similar in all models, their climatological heat and freshwater fluxes are very different. Consistently, the models differ in their mean pathways of the North Atlantic Current, location of upper ocean low salinity waters, as well as in sea ice cover. In the two models with an excessive sea ice extent in the Labrador Sea, most of the water mass transformation in the subpolar region occurs in the eastern part (east of 35°W). The variability of the eastern water mass transformation on decadal time scales is related to the variable warm northward flow into the subpolar region, the upper branch of AMOC, where a strengthened flow leads an intensified transformation. This relationship seems to disappear with a weak connection between the Subtropical and Subpolar gyres.