DETECTION AND ANALYSIS OF OCEANIC THERMAL STRUCTURES USING NOAA AVHRRDATA

The NOAA series of polar satellites have proved highly useful for stud ying the ocean surface. In particular, the radiance information obtain ed through channels 4 and 5 of their Advanced Very High Resolution Rad iometer (AVHRR), which are sensitive to radiation in the thermal infra red, allows sea surface temperature (SST) to be mapped with a precisio n of 0.1-degrees-C. This article describes the way this is done, and h ow such maps can be processed to study oceanic thermal structures and their variation. Particular attention is paid to the detection and mon itoring of the upwelling of cold, nutrient-rich benthic waters from th e ocean floor, since these areas constitute the richest fisheries.