[7] "Spaceborne radar altimeters have proven to be superb tools for mapping ocean-surface topography, the hills and valleys of the sea surface.

Combining these data with the precise location of the spacecraft makes it possible to determine sea-surface height to within a few centimetres (about one inch).

The strength and shape of the returning signal also provides information on wind speed and the height of ocean waves.

NASA evaluated the performance of the following instruments: the Advanced Microwave Radiometer (AMR), the Global Positioning System payload, and the Laser Retroreflector Assembly (LRA).

Data from these missions were used to improve ocean models, forecast hurricane intensity, and identify and track large ocean/atmosphere phenomena such as El Niño and La Niña.

The data was also used in daily applications as diverse as routing ships, improving the safety and efficiency of offshore industry operations, managing fisheries and tracking marine mammals.

This is about twice the estimates from tide gauges for the previous century, indicating a possible recent acceleration in the rate of sea level rise.

The data record from these altimetry missions has given scientists important insights into how global sea level is affected by natural climate variability, as well as by human activities.

Thousands of kilometres wide, these waves are driven by wind under the influence of Earth's rotation and are important mechanisms for transmitting climate signals across the large ocean basins.

At high latitudes, they travel twice as fast as scientists believed previously, showing the ocean responds much more quickly to climate changes than was known before these missions.

The change of water level due to tidal motion in the deep ocean is known everywhere on the globe to within 2.5 centimetres (one inch).

There, the energy is consumed by mixing water of different properties, a fundamental mechanism in the physics governing the general circulation of the ocean.

Validated data products in support of improved weather, climate and ocean forecasts were distributed to the public within a few hours of observation.