Seasonal Variation of Temperature and Salinity of Surface Waters of the British Columbia Coast

Abstract

Grand monthly means of daily observations of surface sea-water temperature and salinity from twelve light stations along the British Columbia coast during the 13 years 1935 to 1948 have been analysed. In general the temperatures reach a minimum of 45°F. ± 1° (7.2 °C. ± 0.5°) in January and February. The maximum varies from 50° to 64°F. (10° to 18 °C.) in August. The warmest waters occur in bays protected from wind action, and the coldest waters occur in regions of turbulent mixing due to wind or strong currents. The salinity along the mainland coast is a minimum in early summer, associated with the maximum run-off from melting snow. Along the west coast of Vancouver Island the minimum occurs in mid-winter, associated with maximum precipitation which is not stored as snow in this region. At the southern and northern tip of the Queen Charlotte Islands there is little or no variation of salinity because there is no land drainage of consequence in the vicinity.In passes between Georgia Strait and the sea where the waters are mixed to homogeneity by strong tidal currents the annual variation of temperature and salinity is reduced, and in some cases entirely suppressed.On the west coast of Vancouver Island it is shown that the annual cycle is affected by the dominant winds and upwelling of deep ocean waters.