Coupling of eastern and western subpolar North Atlantic: salt transport in the Irminger Current
A. Born1,2, T. F. Stocker1,2, and A. B. Sandø3,41Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland 2Oeschger Centre for Climate Change Research, Bern, Switzerland 3Institute for Marine Research, Bergen, Norway 4Bjerknes Centre for Climate Research, Bergen, Norway
Received: 22 Feb 2013 – Accepted for review: 07 Mar 2013 – Discussion started: 15 Mar 2013
Abstract. Salt transport in the Irminger Current and thus the coupling between eastern and western subpolar North Atlantic plays an important role for climate variability across a wide range of time scales. High-resolution ocean modeling and observations indicate that salinities in the eastern subpolar North Atlantic decrease with enhanced circulation of the North Atlantic subpolar gyre (SPG). This has led to the perception that a stronger SPG also transports less salt westward. In this study, we analyze a regional ocean model and a comprehensive global coupled climate model, and show that a stronger SPG transports more salt in the Irminger Current irrespective of lower salinities in its source region. The additional salt converges in the Labrador Sea and the Irminger Basin by eddy transports, increases surface salinity in the western SPG, and favors more intense deep convection. This is part of a positive feedback mechanism with potentially large implications for climate variability and predictability.
Born, A., Stocker, T. F., and Sandø, A. B.: Coupling of eastern and western subpolar North Atlantic: salt transport in the Irminger Current, Ocean Sci. Discuss., 10, 555-579, doi:10.5194/osd-10-555-2013, 2013.