Hydrographic investigations in the Irminger Sea in the years 1954-1964

1. The data examined consist of hydrographic sections in the western Irminger Sea and serial observations at Ocean Weather Station Alpha (Station A). The sections were worked in the years 1959 and 1961 -1964, and at station A the data were collected during 5 periods of observation in the years 1954-1963. 2. The sections as well as the data from Station A are used to give the characteristics and extent of different water masses. The occurence of possible annual variations is also examined. 3. South of the Denmark Strait it is difficult to characterize Polar water by means of temperature and salinity, but 34.50 ‰ seems to be the upper limit of its salinity. 4. The intermediate water in the Irminger Sea is found at about 1 000 m depth, and T-S relations for the data from Station A show that the minimum temperature and salinity of intermediate water are 3.5° C and 34.88 ‰. 5. In the Denmark Strait Arctic Intermediate water exhibits temperatures near, or below, 1°C, and salinities chiefly below 34.90 ‰. This water mass seems to be the main source of the bottom water in the Irminger Sea. 6. The amount of Atlantic water which is carried to the Irminger Sea by the Irminger Current, varies from year to year. These variations are studied in the western branch of the Irminger Current and at Station A. In 1954-1956 only small amounts of Atlantic water were observed, but the Atlantic inflow increased until 1959-1960. During the years after 1961 the amount decreased again. 7. At Station A the wind conditions are examined, and there is a close relationship between the accumulated wind and the mean salinity in the different periods of observation