From Poseidon-1 to Poseidon-2

Image of the month - January 2002

One of the first echos packets received by the Poseidon-2 altimeter. (Credits Cnes) .

December 10, 2001: Poseidon-2, altimeter onboard Jason-1 took its first measurements over the Black Sea. More than nine years earlier, on August 21, 1992, Poseidon-1, onboard Topex/Poseidon was put on over the Guinea Gulf. Between those, altimetry proved its abilities and possibilities in the scientific, technic as well as practical fields.

The design of Poseidon-2 has been enhanced in several areas. In particular, a second frequency has been added (in the C-band) for ionosphere corrections, sampling has been improved, and digital components have replaced analog circuits wherever possible.

First Poseidon "waveforms" (left Poseidon-2, right Poseidon-1). Waveforms represent the time variations of the radar wave power after reflexion on the sea surface. From the shape and amplitude of this curve, the different altimetric "measurements" are extracted: surface-satellite distance, wave height, wind speed.
(Credits Cnes/CLS)