A Satellite-Aircraft Thermal Study of the Upwelled Waters off Spanish Sahara

Abstract

During the period 18 through 26 August 1973, a satellite-aircraft oceanographic survey was made of the upwelled waters off the coast of Spanish Sahara. NOAA-2 infrared data received by a field satellite receiver station and computer-enhanced into thermal imagery aided in directing the five flights of a research aircraft over the region's most interesting thermal features. This imagery showed that the upwelling extended from the Canary Islands southward to 20N in the region of Cape Blanc, and that the aircraft survey would best be made along the coast between 26 and 28N. The aircraft used an airborne radiation thermometer to collect data showing the ocean's surface temperature variations, and 300 m airborne expendable bathy-thermographs to derive the ocean's vertical temperature variation. In addition to aiding the survey operation, the field-collected satellite infrared data were retained in digital form to aid the post-survey analyses. The analyses of the satellite and aircraft data define the region of upwelling and show that during the survey, variable cold and warm eddies extended more than 100 km beyond the upwelling zone. These analyses indicate that the eddies are a result of wind stress and regional topography and may be a periodic dynamic feature of the region.