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AGU: Geophysical Research Letters

 

Keywords

  • Atlantic
  • meridional overturning
  • orography
  • stability

Index Terms

  • Atmospheric Processes: Climatology (1616, 1620, 3305, 4215, 8408)
  • Atmospheric Processes: Ocean/atmosphere interactions (0312, 4301, 4504)
  • Oceanography: Physical: General circulation (1218, 1222)

Abstract

GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L02705, 7 PP., 2012
doi:10.1029/2011GL050485

Mountain ranges favour vigorous Atlantic meridional overturning

Key Points
  • Mountains favour a strong Atlantic overturning
  • Mountains control the magnitude and pattern of freshwater forcing
  • We may have to reassess the vulnerability of the AMOC to collapse

Bablu Sinha

National Oceanography Centre, Southampton, UK

Adam T. Blaker

National Oceanography Centre, Southampton, UK

Joël J.-M. Hirschi

National Oceanography Centre, Southampton, UK

Sarah Bonham

School of Earth and Environment, University of Leeds, Leeds, UK

Matthew Brand

National Oceanography Centre, Southampton, UK

Simon Josey

National Oceanography Centre, Southampton, UK

Robin S. Smith

NCAS-Climate, Department of Meteorology, University of Reading, Reading, UK

Jochem Marotzke

Max Planck Institute for Meteorology, Hamburg, Germany

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 25°N 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.

Received 29 November 2011; accepted 13 December 2011; published 21 January 2012.

Citation: Sinha, B., A. T. Blaker, J. J.-M. Hirschi, S. Bonham, M. Brand, S. Josey, R. S. Smith, and J. Marotzke (2012), Mountain ranges favour vigorous Atlantic meridional overturning, Geophys. Res. Lett., 39, L02705, doi:10.1029/2011GL050485.

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