Strange as it may seem, the surface of the ocean is not flat. It contains hills and valleys which are an echo of the ocean floor. Another factor influencing the level of the mean sea surface is the circulation of the oceans involving warm and cold currents, factors which contribute significantly to our climate. These features are recorded in detail by ERS-1 's Radar Altimeter as it sweeps across the oceans.
This image of the mean sea surface elevation over the North Atlantic exhibits many topographical features, such as the mid-ocean ridge and the continental shelfs. The corresponding mean sea level variations amount to tens of metres, he Radar Altimeter determines with a precision of two centimetres at high l resolution. These data improve our knowledge of the Earth's gravity field and enables us to identify small-scale structures and changes of ocean currents.
Mean sea surface topography derived from ERS-1 Radar Altimeter data.
(Photo: Carel Wakkers, TU Delft, the Netherlands)