- March 9, 2009
- Posted by: EARSC
- Category: EARSC News
After its launch on 20 June 2008, Jason-2 has trailed 55 seconds behind its predecessor Jason-1 during more than 6 months so as to enable scientists to acquire near-simultaneous measurements to precisely calibrate the satellite’s instruments.
As a part of this calibration/validation process of the high accuracy of Jason-2 off-line products (GDR), an update of the Advanced Microwave Radiometer (AMR) and Poseidon-3 altimeter characterization files was planned on 18 February 2009. These files are used to characterise both instruments and the evolution of their accuracy over time.
On 14 February 2009 Jason-2 has been finally moved into the orbit of its predecessor, while the later has been moved to a new orbit to double coverage of the ocean surface. As a result, the two satellites started flying in tandem on parallel ground tracks. These orbital manoeuvres signed the end of the Jason-2’s calibration and validation phase.
Normally, the Jason satellites need 2 hours to orbit Earth, while at the same time the planet rotates eastwards which means that the resulting ground track of the satellites cannot cover the entire surface of the globe. The Jason-1’s new orbit is midway between 2 adjacent Jason-2 ground tracks, which ensure a resolution equivalent to that of a Jason satellite orbiting Earth in only 1 hour.