Ionian Sea surface temperature: satellite and drifter observations, May to October, 1995

Abstract

The Ionian Sea is the central basin of the Mediterranean Sea and has been the subject of various oceanographic studies since the 19th century. Substantial changes in water properties (such as temperature), both spatially and temporally (seasonal) occur as a result of extreme forcings by the local winds and by the inflow of cool and less saline Atlantic waters. In recent years, extensive measurements have been made, primarily through remote sensing techniques. In particular, satellite infrared data were used to study the surface thermal features and associated circulation. In order to improve upon previous results, this study focuses on a period of 6 months (May to October, 1995) in which the full resolution (1.25x1.25 km) satellite images are used to describe and study the variability of the sea surface temperature (S ST) and circulation from meso- (days) to seasonal (months) scales. The satellite infrared temperatures are compared to simultaneous and collocated in-situ drifter temperature measurements. They are corrected by removing biases obtained by regression analysis. The corrected images are used to produce maps representing daily, three-day, weekly and monthly Ionian SSTs. Selected SST composites augmented with drifter track and wind field overlays disclose important quantitative features of the Ioman surface waters, such as upwelling events in the Straits of Otranto and of Sicily, and off the African Coast. The spatial structure and temporal variability of the surface fields are presented and discussed