To get the biggest picture now available, Paolo and his colleagues stitched together satellite
radar altimetry data from three consecutive and overlapping missions: the European Space Agency's (ESA's)
ERS - 1 and
ERS - 2 (which flew from 1991 to 2000 and 1995 to 2011, respectively), and ESA's ENVISAT mission, which collected data from 2002 to 2012.