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A model for the response of waves to turning wind was recently derived from the growth–fetch relations for developing waves. An essential part of the model involves the drag coefficient Cd. Recently, the ERS-1 Grand Banks (GB) Wave Validation Experiment of 1991 measured wind speed and wave parameters at an open ocean position about 205 km from land. The GB experiment also measured Cd and therefore provides the first complete verification of the model in open ocean conditions.

A model is developed for the response of waves to turning wind, which we denote as the fetch relaxation model. Comparison is presented with the standard 𝒷 relaxation model pioneered by Hasselmann et al. The fetch relaxation model is shown to surpass the standard 𝒷 model, with respect to observations collected during the Canadian Atlantic Storm Program (CASP) of 1986. Both models are based on the premise that the net growth of energy due to the wind is centered on the wind direction. The fetch relaxation model also conforms to relations for fetch-limited growing waves derived from the CASP observations. Moreover, the fetch relaxation model is shown to provide estimates for the role of the drag coefficient in turning wind situations.

Field experiments, in the years since the JONSWAP results, have established fetch- and duration-limited relations for wave parameters such as total energy E0, peak frequency fp, and the Phillips α coefficient. The Canadian Atlantic Storms Program (CASP) Experiment of 1986 also found that the wind speed profile appropriate for the fetch-limited wave relations is a function of fetch, due to the change in surface roughness at the shoreline. Moreover, the fetch-limited wave relations may be altered by assuming differing wind speed variations with fetch. Inverting accepted fetch-limited wave relation the authors inter a fetch-limited relation for wind speed (or friction velocity) in terms of spectral wave parameters such as wave age. These relations are verified from measurements collected during CASP.

We present the variation that results when fetch relations for wind-generated wave spectra are sealed by the friction velocity component in the dominant wave direction rather than the magnitude of the friction velocity, using the data collected during the Canadian Atlantic Storms Program (CASP). The effects of three possible drag coefficients are considered. the usual constant drag coefficient, the open-ocean long fetch drag coefficient, and finally, the wave age dependent drag coefficient for growing waves recently measured by Smith and Anderson in HEXOS. Contributions to the correlation coefficients for dimensionless variables due to both scaling variables and dimensional variables are computed. We find that the friction velocity component in the dominant wave direction rather than the friction velocity magnitude should be used as the scaling variable. The self-correlation introduced to the correlation coefficients is then less than that resulting from the friction velocity magnitude. Balance r...

The Green's function for a semi-infinite ocean with depth a function of distance from the boundary is developed numerically for the M2 frequency and with Coriolis frequency and depth profile appropriate to the continental slope off the Gulf of Maine. This involves numerical integration of the linearized shallow water equations for all longshore wavenumbers, followed by numerical Fourier transformation. This variable-depth Green's function is approximately equal to Buchwald's (1971) constant-depth Green's function for distances along the boundary greater than the width of the slope, and at very short range tends to limiting values which can be approximated analytically. The Green's function, when combined with currents from Greenberg's (1979) numerical model of the Bay of Fundy and Gulf of Maine, is used to explain substantial observed variations in M2 amplitude and phase along the edge of the shelf off the Gulf of Maine; the variable-depth Green's function produces significantly better results th...

A simple model in which the cross-strait sea surface slope is geostrophically balanced and the along-strait slope is balanced by acceleration and friction, is shown to be supported by the results of Buchwald and Miles for fluctuating flow through a gap between two semi-infinite oceans. For a narrow gap (compared with the Rossby radius and the scale of the motion in the far field), the transport through it is exactly the same as that predicted by the model, provided that the gap is regarded as having an elective length as determined in this paper. The importance of the models is that they demonstrate that, at low frequency, the flow may be “geostrophically controlled” and the transport limited to a value much less than that which would arise in a nonrotating system. The neglect of nonlinear advective terms in the models is justified by a comparison or the Bernoulli set-down in the strait with the driving head and the mean water depth. The formula for the flux through a strait may be applied in stu...

We present an analysis of 84 days of current meter, sea level and hydrographic data collected in the Strait of Belle Isle, a long, narrow strait which connects the Atlantic Ocean and the Gulf of St. Lawrence. Along-strait currents are highly coherent throughout the entire cross section of the strait at all frequency, but the ratio of near-bottom to near-surface flows shows a well defined increase with increasing frequency. This frequency dependence is compared to the model of Garrett and Petrie after modification to allow for the finite thickness of the bottom Ekman layer. The model can best account for the frequency-dependent amplitude ratio if the spindown time in the strait is 4 hours. We also compare the model predictions to observations of the ratio of the surface minus bottom pressure fluctuation on the north side of the strait to the pressure fluctuation difference across the strait at the surface. We again find reasonable agreement with theory for a friction parameter corresponding to a s...