A description of summer physical oceanographic conditions in Rupert Bay (James Bay, Canada)

Renewed interest in the oceanography of the James Bay region of Canada has arisen because of plans to develop hydroelectric projects on many of the rivers in northern Quebec. Measurements of current velocity, temperature, salinity and water level were made over a period of two months in Rupert Bay. From an analysis of the current meter time series, the circulation and distribution of physical properties were found to be dominated by the tides, with the semi-diurnal component being the predominant component. An analysis of variance revealed that 77% of the salinity variations were related to tides. Vertically homogeneous conditions prevailed in many areas because of a large tidal amplitude/depth ratio of 0.625, causing intense mixing in two-thirds of the estuary. Non-tidal velocity components were found to be 0(1) less than tidal currents, with long term mean circulation directed out of the bay. Non-tidal water level variations were well correlated with the wind. The maximum cross-correlation coefficient was calculated to be 0.77 for a 7 hour lag. The centrifugal force, Coriolis force, and baroclinic pressure gradient were dominant forces driving the secondary flows to the bay. Tidal fronts were found to be either aligned parallel to the main axes of principle channels or around small downstream islands with the arrangement influenced by bottom topography. 27 refs., 11 figs., 5 tabs