Using all available oceanographic data in the Gulf of St. Lawrence between 1950 and 1969, a network of average stations was formed for the months of June, July, August, November, and for the winter period. The dynamic method was applied to calculate the geostrophic circulation in the Gulf during these months based on a variable reference layer.The main features of the reference layer are the steep slope along the Gaspé coast and the existence of three depressions in the Laurentian Channel, southeast and west of Anticosti Island, and in the central region of Cabot Strait. Its depth varies from 10 to 50 m in the Magdalen Shallows to more than 300 m in part of the Laurentian Channel. The general two-way flow in all entrances to the Gulf, the existence of a permanent anticlockwise gyre west of Anticosti Island, and the Gaspé and Cape Breton currents with which are associated the highest velocities in the Gulf are the main features of the circulation pattern. The circulation patterns obtained agree with the results of synoptic observations.Cyclonic and anticyclonic gyres are common in the Gulf. A comparison of the circulation patterns obtained in this study and the results of the International Biological Programme Study of the Gulf reveal that such cyclonic and anticyclonic gyres are responsible, at least in part, for the areas of maximum primary productivity west and northeast of Anticosti Island, and for the so-called "desert areas" in the northeastern side of the Gulf.

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A transect across the lower St. Lawrence estuary was occupied to estimate volume transport and nutrient distributions (total dissolved nitrogen and phosphorus, and silicate) during February and May through September. Seaward transport was restricted to the upper 50 m and varied from 17 × 103 m3/s (August) to 129 × 103 m3/s (May). Nutrient and volume transport data are combined to estimate seasonal variability in monthly surface nutrient transport towards the Gulf of St. Lawrence. The estimates vary as follows: 0.72–6.72 × 103 tons N/mo, 0.05–0.48 × 103 tons P/mo and 0.50–6.73 tons Si/mo. Ratios between monthly freshwater input into the estuary and the corresponding values for net seaward transport, which varied from 1.1 to 9.4, are combined with annual data (1960–73) on monthly freshwater input into the estuary to estimate potential annual variability in seaward transport for each of the above months. Observed nutrient data, with the above transport estimates, suggest the possible range in monthly seaward nutrient transport that would be associated with the annual variability in monthly freshwater input into the estuary. Seaward nitrogen transport from May through September, estimated at 2.3 × 104 tons, is considered in relation to published data on the primary production in the western part of the Gulf of St. Lawrence. The estuary supplied a smaller amount of nutrients to the Gulf than has previously been assumed.

The storm surge phenomenon in the Arabian Gulf, including the Strait of Hormuz, is discussed with particular emphasis on the development of mathematical models for prediction purposes. The Gulf is mainly influenced by extra-tropical weather systems, whereas the region south of the Strait of Hormuz is affected by tropical cyclones. The west-to-east directed extra-tropical cyclone tracks and the generally east-to-west directed tropical cyclone tracks converge near the Strait of Hormuz. A meso-scale weather system that deserves special attention in prescribing the meteorological forcing functions is the so-called 'winter Shamal'. A two-dimensional numerical model is developed to study the storm surges in the Arabian Gulf. The results show that the Gulf is subject to major negative and positive storm surges. Strong winds associated with the Shamal system, coupled with atmospheric pressure gradients, topography and tidal effects, can give rise to water level deviations of several meters. Storm surges observed during the period 17-19 January 1973 show that negative values in the 0.5 to 1.0m range were widespread in the Gulf.

CTD and current meter data from the northwestern Gulf of St. Lawrence were analyzed to study the structure and variability of the Gaspé Current. Since the current is buoyancy driven, its properties are strongly influenced by the seasonal variation of the freshwater discharge from the St. Lawrence estuary. From June to November, maximum speed decreases from 110 cm s−1 to 60 cm s−1. High vertical shears exist in the upper 40 m of the water column. During the same period, the width of the current decreases, and the position of the current maximum shifts from near the shore to about 14 km from the shore. These changes in the structure can be understood in terms of geostrophy and baroclinic deformation radius. In the temperature/salinity field the most prominent change from June to November is the continuing increase of surface salinity. Temperature change occurs mainly in the September‐November period, when atmospheric cooling accelerates. The effect of atmospheric cooling is also reflected in the density distribution, with the result that in November currents in the upper 30 m are seaward in the entire section (from Sept‐Iles to Marthe de Gaspé), while in the summer months the currents are seaward in the southern part and westward in the northern part of the section. Momentum balance of the current system is also investigated. It was found that east of Pointe‐des‐Monts, geostrophic balance is maintained, while west of Pointe‐des‐Monts the observations do not seem to be consistent with the assumption of geostrophy.