Description

Altimetry is a technique to measure the height of a ground target from the satellite. It was developed in the 1970’s soon after the flight of artificial satellites became a reality. The main advantages of radar altimetry include day/night coverage in all weather conditions with no loss of data because of cloud coverage. With continuous operation across all the surfaces, the instrument behaves like a string of pseudo-gauges, measuring the elevation at a discrete interval along a narrow ground track. The presence of vegetation or canopy cover is not a hindrance to this nadir-viewing instrument, the inundated surfaces being so bright at microwave frequencies that vegetation only interferes during periods of extremely low water level. The satellite radar
altimeter can thus observe monthly, seasonal, and inter-annual variations during the lifetime of the mission. Unlike many gauge networks that operate using a local reference frame, all altimetric height measurements are given with respect to one reference datum to form a globally consistent, uniform data set.