Hydrographic surveys off Plymouth in 1959 and 1960

Abstract

SUMMARYAn area in the English Channel of about 30 x 45 miles centred on a position about 25 miles south of Plymouth was surveyed twice in 1959 and six times in i960. Temperature and salinity were measured at 0, 10 and 50 m, and phosphate and silicate concentrations at 10 and 50 m.Lower temperatures were usually found near the coast, though the converse was observed in October i960.Isotherms generally ran east-west in winter and north-south in summer.Salinity was usually lower near the coast, but not in the summer.Density contours generally resembled those of temperature, and suggested an eastward water movement in winter. In summer they suggested an offshore movement at the surface and an onshore movement of the deeper water.In winter the distribution of phosphate and silicate resembled that of salinity, high values of nutrients corresponding to low salinities.In summer the depth of thermocline was greater to the westThe properties of the water were so variable from place to place, and changes in them so rapid, that it is difficult to accept results from station Ei, or any other single station in the area, as typical of the whole.