Wave height from space

As well as mapping the height of the sea surface, data from the altimeter is useful for measuring waves.  Significant wave height – trough to crest of the tallest third of waves – together with wind speed over the ocean are known collectively as ‘sea state’. In the coastal zone, radar altimetry data is particularly useful for understanding storm surges, as it can be used to determine the ‘total water level envelope’, which includes the mean rise in water levels as well as the waves riding on top. Waves can ‘over-top’ coastal defences and cause catastrophic flooding, sediment transport, damage to infrastructure and loss of life.