The wind-forced response on a buoyant coastal current: Observations of the western Gulf of Maine plume

被引:97
作者
Fong, DA [1 ]
Geyer, WR [1 ]
Signell, RP [1 ]
机构
[1] US GEOL SURVEY,WOODS HOLE,MA 02543
关键词
Gulf of Maine; upwelling; continental shelf; freshwater; buoyancy currents; longshore currents;
D O I
10.1016/S0924-7963(96)00089-9
中图分类号
P [天文学、地球科学];
学科分类号
07 ;
摘要
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.
引用
收藏
页码:69 / 81
页数:13
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