Intraseasonal to Interannual Variability of the Atlantic Meridional Overturning Circulation from Eddy-Resolving Simulations and Observations

• Main Authors: Xu, Xiaobiao, Chassignet, Eric P, Johns, William E, Schmitz, Jr, William J, Metzger, E J
• Other Authors: NAVAL RESEARCH LAB STENNIS DETACHMENT STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
• Format: Text
• Language: English
• Published: 2014
• Subjects: Physical and Dynamic Oceanography; Fluid Mechanics; *ATLANTIC OCEAN; OCEAN CURRENTS; OCEAN MODELS; AMOC(ATLANTIC MERIDIONAL OVERTURNING CIRCULATION); VARIABILITY; HYCOM SIMULATIONS; PE0602435N; WU73-8677-03-5; Antarctic; The Antarctic; Antarc*; North Atlantic
• Online Access: http://www.dtic.mil/docs/citations/ADA610198; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA610198

Results from two 1/12 degree eddy-resolving simulations, together with data-based transport estimates at 26.5 deggrees N and 41 degrees N, are used to investigate the temporal variability of the Atlantic meridional overturning circulation (AMOC) during 2004 2012. There is a good agreement between the model and the observation for all components of the AMOC at 26.5 degrees N, whereas the agreement at 41 degrees N is primarily due to the Ekman transport. We found that (1) both observations and model results exhibit higher AMOC variability on seasonal and shorter time scales than on interannual and longer time scales; (2) on intraseasonal and interannual time scales, the AMOC variability is often coherent over a wide latitudinal range, but lacks an overall consistent coherent pattern over the entire North Atlantic; and (3) on seasonal time scales, the AMOC variability exhibits two distinct coherent regimes north and south of 20 degrees N, due to different wind stress variability in the tropics and subtropics. The high AMOC variability south of 20 degrees N in the tropical Atlantic comes primarily from the Ekman transport of the near-surface water, and is modulated to some extent by the transport of the Antarctic Intermediate water below the thermocline. These results highlight the importance of the surface wind in driving the AMOC variability. Published in Journal of Geophysical Research: Oceans, online 12 Aug 2014; DOI 10.1002/2014JC009994. Prepared in collaboration with 1Center for Ocean-Atmospheric Prediction Studies, Florida State University, Tallahassee, FL; Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, FL; and Harte Research Institute, Texas A & M University-Corpus Christi, Corpus Christi, TX. The original document contains color images.