Satellite Observations as Indicators of the Mediterranean Sea’s Health

Abstract

Satellite observations of the marine environment allow the assessment of optical, thermal and structural properties, which can be inferred from the interaction of electromagnetic radiation with the water surface. An evaluation of features in the Mediterranean Sea has been obtained using data collected in the 1980s and 1990s by a suite of visible/infrared radiometers and radar altimeters. The derived colour, temperature and wind fields highlight the main processes occurring in the basin. Scales and trends of such processes trace the space–time characteristics of the main provinces in which the basin can be subdivided. These are either areas under the direct influence of coastal interactions, regions of enhanced patterns linked to the prevailing winds and/or currents, or open sea areas, characterized by quasi-latitudinal frontal structures (western basin) and by a permanent mesoscale eddy field (eastern basin). In the time domain, a general pattern of higher pigment levels and lower temperatures develops in winter, under the forcing of higher wind speed, and then reverses in summer, as if the Mediterranean was behaving like a subtropical basin. Some provinces have a distinct seasonality (e.g. that of a subpolar basin in the northwest), possibly owing to diverse environmental boundary conditions. Geographic and climatic traits of the basin and its continental margins and water circulation patterns appear to shape provinces and seasons. These results suggest that satellite observations can provide useful information for the assessment of marine regions, of their environmental health and of their most critical processes.