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Topographical Control of the Source‐Sink and Wind Stress‐Driven Planetary Geostrophic Circulation in a Polar Basin
Author(s) -
Gavilan PascualAhuir Estanislao,
Willmott Andrew J.,
Morales Maqueda Miguel,
Luneva Maria
Publication year - 2020
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2019jc015571
Subject(s) - barotropic fluid , geology , geostrophic wind , ocean gyre , geostrophic current , boundary current , sink (geography) , ocean current , wind stress , circulation (fluid dynamics) , structural basin , climatology , ridge , geophysics , oceanography , mechanics , physics , geomorphology , geography , paleontology , cartography , fishery , biology , subtropics
The effects of topography on the barotropic circulation in a polar basin are examined analytically and numerically. New approximate linear analytical solutions are presented for steady‐state wind and boundary forced barotropic planetary geostrophic circulation in a circular polar basin with a step shelf. The solutions are obtained by retaining the full spherical geometry in the derivation of the forced potential vorticity equation; thereafter the colatitude is fixed in the coefficients of this governing equation. The accuracy of the analytical solutions is evaluated by comparing them with the equivalent numerical solutions obtained using the NEMO modeling system. Subsequently, the impact of a nonuniform width shelf on source‐sink‐driven circulation is investigated numerically. The equipartition of fluid entering the source strait into cyclonic and anticyclonic shelf currents, exiting the basin at the sink strait, in a basin with a uniform width shelf is shown to be modified when the shelf width varies. In general, the wider shelf supports a current with larger transport, irrespective of the azimuthal extent of the wider shelf. The study concludes with a numerical investigation of wind‐driven circulation in a basin with a step shelf, three straits, and a transpolar ridge, a prototype Arctic Ocean simulation. Topographic steering by the ridge supports a transpolar drift current, the magnitude of which depends on the ridge height. Without the ridge, the transpolar drift current is absent and the circulation is confined to gyres on the shelf and in the deep basin.