Abstract

Utilizing 20 days of sea level elevation and current records in mid-Chesapeake Bay, the frequency structure of the meteorological forcing is investigated. For periods longer than 8 days the residual sea level inside the Bay is coupled to the coastal elevation forced by the onshore-offshore component of the wind, while at the 3–8 day scale the system was driven by the local longitudinal wind component. It is suggested, however, that the partition of energy between the longitudinal and lateral wind components may determine whether the Bay responds locally to the wind or to the coastal elevations. The 2–2.5 day sea level oscillations could not be identified with a seiche in the Bay; their source is not clear, but the atmospheric pressure is a possibility.The vertical structure of the residual currents through two cross-sections shows that the layers in the upper 8 m are directly driven by the wind, while in the deeper layers the flow is opposite the wind as a result of the surface slope associated with it. The lag in this counter flow increases from the bottom up and is explained in terms of the phase lag of the surface slope response to the wind and the depth dependence of the current response to the wind.

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