Numerical simulations of the response of intense ocean currents to atmospheric forcing.
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Authors
Adamec, David
Subjects
Ocean simulations
Atmospheric forcing
Gulf Stream
Bottom topography
Momentum mixing
Surface cooling
Wind forcing
Atmospheric forcing
Gulf Stream
Bottom topography
Momentum mixing
Surface cooling
Wind forcing
Advisors
Elsberry, R.L.
Date of Issue
1985-03
Date
Publisher
Monterey, California. Naval Postgraduate School
Language
en_US
Abstract
The two and three-dimensional response of strong ocean currents to atmospheric forcing is
studied using numerical simulations. In particular, surface cooling is explored as a possible
mechanism for explaining an observed 100 km southward shift in the mean position of the Gulf
Stream during winter. The magnitude and direction of the cross-stream circulation is highly
dependent on whether or not a vertical mixing of momentum occurs when the water column
convectively adjusts in response to the surface cooling. A weak cross-stream flow toward the
higher sea-surface temperatures occurs in the surface layer if momentum mixing does not occur,
whereas a stronger flow toward lower sea-surface temperatures results if momentum mixing does
take place. The response of three-dimensional simulations is very similar to the two-dimensional
simulations in the immediate vicinity of the front. The response due to horizontal cooling
gradients is not large enough to displace the Gulf Stream appreciably southward in any of the
numerical simulations. By contrast, a moderate increase in the zonal wind stress is more effective
in displacing the core of the current system than are strong gradients in the surface cooling. The
position of the Gulf Stream has also been observed to change as it encounters changes in the bottom topography. The simulated adjustment of flow to a 200 m seamount is consistent with
the conservation of potential vorticity. The inclusion of surface forcing does not affect the
adjustment to the topography in any of the simulations, and does not steer the flow toward (away
from) the topography so that the characteristics of the downstream flow are changed.
Type
Thesis
Description
Series/Report No
Department
Meteorology
Organization
Identifiers
NPS Report Number
Sponsors
Funder
Format
Citation
Distribution Statement
Approved for public release; distribution is unlimited.