Scientists have gathered in the 'floating city' this week to talk about radar altimetry - measuring the heights of the global sea surface, freshwater bodies, land and ice using spaceborne sensors.

Held every five years, the '20 Years of Progress in Radar Altimetry Symposium' gives participants the opportunity to focus on the challenges overcome to develop our current understanding of Earth's surface variations observed by altimetry.

Radar altimeters record the surface topography along the satellite's ground track. They precisely measure a satellite's height above water, land or ice by timing the interval between the transmission and reception of very short radar pulses.