The wind-forced response on a buoyant coastal current: Observations of the western Gulf of Maine plume
In: Journal of Marine Systems. Elsevier: Tokyo; Oxford; New York; Amsterdam. ISSN 0924-7963; e-ISSN 1879-1573, more
Also appears in:Ruddick, K. (1997). Processes in regions of freshwater influence (PROFILE): selected papers from the 27th International Liège Colloquium on Ocean Hydrodynamics, held in Liège, Belgium, on May 8-12, 1995. Journal of Marine Systems, 12(1-4). Elsevier: The Netherlands. 1-326 pp., more
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| Keywords |
Continental shelf
Freshwaters
Motion > Water motion > Water currents > Nearshore currents > Longshore currents
Properties > Physical properties > Buoyancy
Upwelling
Water > Fresh water
ANW, USA, Maine Gulf [Marine Regions]
Marine/Coastal |
| Authors | | Top |
- Fong, D.A.
- Geyer, W.R.
- Signell, R.P.
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| Abstract |
The freshwater plume in the western Gulf of Maine is being studied as part of an interdisciplinary investigation of the physical transport of a toxic alga. A field program was conducted in the springs of 1993 and 1994 to map the spatial and temporal patterns of salinity, currents and algal toxicity. The observations suggest that the plume's cross-shore structure varies markedly as a function of fluctuations in alongshore wind forcing. Consistent with Ekman drift dynamics, upwelling favorable winds spread the plume offshore, at times widening it to over 50 km in offshore extent, while downwelling favorable winds narrow the plume width to as little as 10 km.Using a simple slab model, we find qualitative agreement between the observed variations of plume width and those predicted by Ekman theory for short time scales of integration. Near surface current meters show significant correlations between cross-shore currents and alongshore wind stress, consistent with Ekman theory. Estimates of the terms in the alongshore momentum equation calculated from moored current meter arrays also indicate a dominant Ekman balance within the plume. A significant correlation between alongshore currents and winds suggests that interfacial drag may be important, although inclusion of a Raleigh drag term does not significantly improve the alongshore momentum balance. |
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