Bright Targets in the Coastal Zone: A Reconstruction Approach Applied to Envisat RA-2 Data

Usage and availability of Sea Surface Height (SSH) information from satellite radar altimeters undergo known limitations in the coastal zone, where such data are of great importance and usefulness. In fact, coastal regions are a crucial zone to be investigated and monitored, due to the high impact of sea level and circulation changes on the environmental security and related economic and societal aspects. It is known that radar returns from the sea surface sometimes present target-like echoes ("bright targets"), especially in correspondence of particular features of the coastal zones, thus entailing a potential interference with SSH measurements. The hyperbolic patterns generated by such spiky echoes in the radargram domain have been tentatively explained as resulting from flat water areas in the proximity of the coastline, but their direct physical mechanism is still unclear. This poster describes the experimentation of a microwave tomographic reconstruction approach applied to Envisat RA-2 averaged waveforms, tested on selected passes over the Pianosa island (a 10 km2 island in the NW Mediterranean), with the aim of identifying the signal contamination sources in terms of their location and extent. The obtained results encourage the idea that the origin of such signatures is associated with particular conditions of the sea surface, that are easier to be found in the proximity of coastal closed areas, such as gulfs.