In the scope of the project COASTALT (Development
of Radar Altimetry Data Processing in the Oceanic Coastal
Zone), funded by the European Space Agency (ESA),
methods have been developed by the authors, at University
of Porto (U.Porto), for the determination of the path delay
caused by the water vapour content in the atmosphere, on
satellite altimetry measurements in coastal zones. In these
areas, the wet tropospheric correction determined from
measurements of microwave radiometers (MWR) on board
altimeter satellites, ceases to be valid in a strip of about
50 km wide around the coast, due to the large footprint
of the radiometer (circle with 30–50 km in diameter,
depending on the MWR frequency).