Some Physical Oceanographic Features of Inlets of Chile

The first systematic study of physical oceanographic characteristics of the fjord inlets of Chile was carried out by the Institute of Oceanography of the University of British Columbia during March 1970 as Phase V of the Hudson 70 Round-the-Americas Expedition of the Bedford Institute, Canada Department of Energy, Mines and Resources.Observations were made of temperature, salinity, and dissolved oxygen at 175 stations in 32 inlets and in the passages outside them, and soundings were made along 3500 km of track. The sounding data are presented as longitudinal sections, and water properties are summarized in temperature–salinity and temperature–dissolved oxygen correlation plots and characteristic diagrams; comparisons are made with observations for the British Columbia and Alaska inlets reported by Pickard in 1961 (18: 907–999) and 1967 (24: 1475–1506) in the Journal of the Fisheries Research Board of Canada. Observations were also made of nutrients in some Chilean inlets; these will be reported at a later date.In mean and extreme values, the dimensions of the inlets in Chile are similar to those in British Columbia/Alaska; only two shallow sills were recorded. More inlets had glaciers contributing melt water directly to them and more had icebergs present than is the case in the northeast Pacific inlets. Vertical salinity profiles in Chile were similar to those in British Columbia/Alaska, but the thinner surface layer was of higher salinity, except in the inlets having icebergs, and the deepwater salinities were 1–2‰ higher in Chile. Temperatures were 2–5 degrees C higher in Chile except in the iceberg inlets where surface values were lower than those in Alaska. Several of the iceberg inlets in Chile had much more complicated temperature/depth profiles than in Alaska, with as many as seven maxima and minima below the surface. The glacial silt in the inlet waters was more conspicuous and extensive in Chile than in British Columbia/Alaska. Dissolved oxygen values in Chile were much the same as in British Columbia/Alaska with higher values in the iceberg inlets in Chile than in Alaska, and there was little evidence of very low values characteristic of stagnant basins. The lack of low dissolved oxygen values suggests free exchange with outside waters and the inlet deepwater characteristics indicate that the effective sill depths between inlets and the ocean are only 100–150 m deep. At least four distinct major regions are evident from water properties among the inlets of Chile.