During a measurement program on the Scotian Shelf off Nova Scotia, large amplitude internal waves were observed in the vicinity of the shelf edge. Some were identified positively as solitons. The observations provide insight into the soliton generation process and explain the role they play in the transfer of energy from tides to ocean mixing. It is found that the shoreward propagating energy in the baroclinic tide, which is generated at the shelf edge, is dissipated by way of the large‐amplitude, short internal waves. Based on observed dissipation rates of solitary waves, it is concluded that the associated amount of mixing is sufficient to supply the required nutrients to the euphotic zone.
An analysis of coastal tide gage records and coincident weather data shows that at synoptic time scales the sea level changes are highly correlated with variations in the alongshore component of wind (better than with wind stress). Regression analysis indicates that there are systematic seasonal differences in how the sea responds to given wind stress. A study based on a simple barotropic model, which agrees with the main observed features, shows that bottom friction becomes important at synoptic time scales. Use of a quadratic friction law yields the solution in which sea level is correlated with wind. The observed phase lags also agree with those predicted by the model. [1977] has recently summarized the evidence for the existence of both freely propagating and wind-forced coastaltrapped long waves and has found good qualitative agreement between some existing measurements and linear wave theory. The two main data sets used for comparison were the pycnocline displacement in Lake Ontario [Csanady and Scott, 1974] and sea level measurements off Oregon [Smith, 1974], although other miscellaneous evidence was presented. In the comparison, surface wind stress values along the path of wave propagation are used to calculate the wave response. Clarke's first-order wave equation does not include dissipation explicitly, but the analysis of sea levels off Oregon suggests that highest average coherences between wind stress and sea levels are occurring for a wave decay time of about 2-5 days. INTRODUCTION ClarkeWe have analyzed sea level data from tide gages along the coast of Nova Scotia from Yarmouth at the southwestern tip to North Sydney on Cape Breton Island (Figure 1), covering an alongshore distance somewhat in excess of 500 km, and we find that the nonisostatic response of sea level is almost entirely correlated with local winds, i.e., the response is strongly forced locally. The suggestion is that since on the Scotian Shelf the predominant weather patterns move from southwest to northeast, the freely propagating shelf waves moving in the opposite direction are excited only weakly. In the case of the forced 'waves' travelling with the weather systems, it seems more appropriate to treat the response as an isolated 'event' rather than as a periodic phenomenon.The plan of this paper is to present the observational evidence in support of statements made in the previous paragraph, to discuss additional aspects appearing from the analysis, and to propose a simple barotropic model of shelf water response to wind forcing which accounts for the main observed features. DATA SET Hourly heights of sea level are available from permanent tide gages at Yarmouth, Halifax, and North Sydney (see map in Figure 1). Meteorological data at hourly intervals are being archived at adjacent weather stations at Yarmouth, Shearwater, and Sydney. Additional data on surface meteorological fields are available from stations at Canso and Sable Island. The latter, situated near the shelf edge on a low sand spit, may be the most representative of c...
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