Satellite Radar Altimeter

Operating at 13 6 or 35 75 ghz each altimeter emits a series of microwave pulses towards the surface.

Satellite radar altimeter.

An altimeter measures how high something is. This measurement is performed through the recording of the pulse bounced back by the reflecting facets within the altimeter footprint. Satellite radar altimetry measures the time taken by a radar pulse to travel from the satellite antenna to the surface and back to the satellite receiver. Combining the physical explanation of the function fitting and the high adaptability of empirical statistical methods we effort to provide a comprehensive method for processing the waveforms over the open ocean and coastal area.

A radar altimeter ra radio altimeter ralt electronic altimeter or reflection altimeter measures altitude above the terrain presently beneath an aircraft or spacecraft by timing how long it takes a beam of radio waves to travel to ground reflect and return to the craft. Waveform retracking for precise sea surface height ssh is an important method to improve the quality of satellite altimeter data. This measurement yields a wealth of information that can be used for a wide range of applications in particular for understanding sea level rise. Surface height is the difference between the satellite s position on orbit with respect to an arbitrary reference surface the earth s centre or a rough approximation of the earth s surface.

Hence ocean viewing altimeters have a small range window whose position tracks the delay and strength of the surface reflection. Satellite radar altimeters measure the ocean surface height sea level by measuring the time it takes a radar pulse to make a round trip from the satellite to the sea surface and back. Radar altimetry measures the two way travel time of a radar pulse between the satellite antenna and the earth s surface at the nadir of the spacecraft. The principle is that the altimeter emits a radar wave and analyses the return signal that bounces off the surface.

The altimeter emits a radar beam that is reflected back to the antenna from the earth s surface. A satellite radar altimeter is not an imaging device but a nadir pointing instrument continuously recording average surface spot heights directly below the satellite as it transverses over the earth s surface. Poseidon 2 operates at two frequencies 13 6 ghz in the ku band 5 3 ghz in the c band to determine atmospheric electron content which affects the radar signal path delay. A satellite based radar altimeter needs to measure the distance accurately but only for an essentially planar surface oriented orthogonally to the radar s line of sight.