Circulation and exchange in choked marginal seas
MetadataShow full item record
A theory for the exchange between a rotating, buoyancy-forced marginal sea and an ocean is developed and tested numerically. Cooling over the marginal sea leads to sinking and sets up a two-layer exchange flow, with a warm surface layer entering from the ocean and a cool layer exiting at depth. The connecting strait is sufficiently narrow and shallow to cause the exchange flow to be hydraulically controlled. The incoming surface layer forms a baroclinically unstable boundary current that circles the marginal sea in a cyclonic sense and feeds heat to the interior by way of eddies. Consistent with the overall heat and volume balances for the marginal sea, there is a continuous family of hydraulically controlled states with critical flow at the most constricted section of the strait. Included in this family is a limiting “maximal-exchange” solution with two sections of hydraulic control in the strait and with fixed layer depths at the most constricted section. The state of exchange for a given forcing is predicted using a theory that assumes energy conservation over a certain path connecting the strait to the marginal sea or, in some cases, the ocean. Depending on the configuration of the exchange, long-wave information may be blocked from entering the strait from the marginal sea, from the open ocean, or both. The scenario that holds determines what is predicted and what needs to be input. Numerical tests of the prediction for the temperature difference and the state of exchange are carried out for straits with a pure contraction in width and for a constant width strait with a topographic sill. The comparison is reasonable in most cases, though the numerical model is not able to reproduce cases of multiple states predicted by the theory for certain forcing values. The analytical model is an alternative to the Price and Yang and Siddall et al. models of a marginal sea outflow.
Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 2639-2661, doi:10.1175/2008JPO3946.1.
Showing items related by title, author, creator and subject.
Meyer, Amelie; Sloyan, Bernadette M.; Polzin, Kurt L.; Phillips, Helen E.; Bindoff, Nathaniel L. (American Meteorological Society, 2015-04)A key remaining challenge in oceanography is the understanding and parameterization of small-scale mixing. Evidence suggests that topographic features play a significant role in enhancing mixing in the Southern Ocean. This ...
Wang, Guihua; Xie, Shang-Ping; Huang, Rui Xin; Chen, Changlin (American Meteorological Society, 2015-11-01)The subsurface ocean response to anthropogenic climate forcing remains poorly characterized. From the Coupled Model Intercomparison Project (CMIP), a robust response of the lower thermocline is identified, where the warming ...
Near-surface transport pathways in the north Atlantic Ocean : looking for throughput from the subtropical to the subpolar gyre Rypina, Irina I.; Pratt, Lawrence J.; Lozier, M. Susan (American Meteorological Society, 2011-05)Motivated by discrepancies between Eulerian transport estimates and the behavior of Lagrangian surface drifters, near-surface transport pathways and processes in the North Atlantic are studied using a combination of data, ...