Mountain ranges favour vigorous Atlantic Meridional Overturning

Sinha, B., Blaker, A., Hirschi, J., Bonham, S., Brand, M., Josey, S., Smith, R. ORCID: https://orcid.org/0000-0001-7479-7778 and Marotzke, J. (2012) Mountain ranges favour vigorous Atlantic Meridional Overturning. Geophysical Research Letters, 39. L02705. ISSN 0094-8276 doi: 10.1029/2011GL050485

Abstract/Summary

We use a global Ocean-Atmosphere General Circulation Model (OAGCM) to show that the major mountain ranges of the world have a significant role in maintenance of the Atlantic Meridional Overturning Circulation (AMOC). A simulation with mountains has a maximum AMOC of 18 Sv (1 Sv=106 m3 s-1) compared with ~0 Sv for a simulation without mountains. Atlantic heat transport at 25N is 1.1 PW with mountains compared to 0.2 PW without. The difference in AMOC is due to major changes in surface heat and freshwater (FW) fluxes over the Atlantic. In the Pacific changed surface fluxes lead to a meridional overturning circulation of 10 Sv. Our results suggest that the effects of mountains on the large-scale atmospheric circulation is to force the ocean towards a state with a vigorous AMOC and with no overturning in the Pacific.