The variability of oceanographic observations off the coast of north-west Africa

Abstract

During may–June 1969 two sections, 30 nautical miles apart, were worked off the coast of north-west Africa near Cape Blanc. Temperature, salinity, phosphate, silicate and nitrate were observed to a depth of 500 metres. Both sections were worked on three occasions, separated by periods of 50 and 77 hours respectively. Considerable variations in the distribution of the parameters was observed, both between successive surveys of the same section and also between the two sections of the same survey. Observations were also made over a period of 24 hours at two locations on the edge of the continental shelf, and marked variation with time in the distribution of the parameters was recorded at both locations. The nature of the variability is discussed in the light of the upwelling process operating throughout the period of observation.