Diagnosing the Observed Seasonal Cycle of Atlantic Subtropical Mode Water Using Potential Vorticity and Its Attendant Theorems.

• Published in: Journal of Physical Oceanography
• Main Authors: Maze, Guillaume, Marshall, John
• Other Authors: Department of Earth, Atmospheric and Planetary Sciences MIT, Cambridge (EAPS), Massachusetts Institute of Technology (MIT), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2011
• Subjects: Atlantic Ocean; Water masses; Seasonal cycle; Potential vorticity; Ocean circulation; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-00650712; https://doi.org/10.1175/2011JPO4576.1

International audience Analyzed fields of ocean circulation and the flux form of the potential vorticity equation are used to map the creation and subsequent circulation of low potential vorticity waters known as subtropical mode water (STMW) in the North Atlantic. Novel mapping techniques are applied to (i) render the seasonal cycle and annual-mean mixed layer vertical flux of potential vorticity (PV) through outcrops and (ii) visualize the extraction of PV from the mode water layer in winter, over and to the south of the Gulf Stream. Both buoyancy loss and wind forcing contribute to the extraction of PV, but the authors find that the former greatly exceeds the latter. The subsequent path of STMW is also mapped using Bernoulli contours on isopycnal surfaces.