The influence of variability in meridional over turning on global ocean circulation

Journal Article · Fri Jul 02 00:00:00 EDT 2021 · Journal of Climate

DOI:https://doi.org/10.1175/jcli-d-21-0119.1· OSTI ID:1827725

Hu, Aixue ^[1]; Meehl, Gerald A. ^[2]; Rosenbloom, Nan ^[2]; Molina, Maria J. ^[2]; Strand, Warren. G. ^[2]

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1. National Center for Atmospheric Research, Boulder, CO (United States); National Center for Atmospheric Research
2. National Center for Atmospheric Research, Boulder, CO (United States)

The Atlantic Meridional Overturning circulation (AMOC) is an important global scale circulation and changes in AMOC can induce significant regional and global climate impacts. In this work, we study the stability of AMOC and its influence on global ocean circulation and the surface climate though analyzing a set of sensitivity experiments using the Community Climate System Model version 1 (CESM1). Results show that a collapsed AMOC can induce changes in global ocean circulation, such as reduced (or reversed) Bering Strait transport, weakened Indonesia throughflow and Agulhas current, but strengthened Drake Passage transport. It also changes the global wind pattern and surface temperature, such as a seesaw-like surface temperature change between Northern and Southern Hemispheres, a weakening of Indian-Australia summer monsoon, a southward shift of the Southern ocean westerlies, etc. We also found that AMOC and the Pacific deep meridional overturning circulation (or PMOC) do not form a natural seesaw under modern day climate and geography. A collapsed AMOC (active PMOC) is not stable under modern conditions if there is no additional freshwater (salt) input in the subpolar North Atlantic (Pacific), suggesting that the modern mean state of AMOC (PMOC) does not depend on local haline forcing although its variability and changes do.

• Research Organization: National Center for Atmospheric Research, Boulder, CO (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: 89243018SSC000007; AC02-05CH11231
• OSTI ID: 1827725
• Journal Information: Journal of Climate, Journal Name: Journal of Climate Journal Issue: 18 Vol. 34; ISSN 0894-8755
• Publisher: American Meteorological Society
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
Coupled models
Meridional overturning circulation
Ocean circulation
Oceanic variability