Gavdos-Crete Cal-Val for satellite altimetry missions
“Monitoring, Calibration and Validation of current (i.e., Jason-1, Jason-2/OSTM, HY-2) and future (i.e., Jason-3, Sentinel-3, Altika/SARAL) satellite altimetry measurements using the permanent facility on the islands of Gavdos and Crete, Greece"
- (Geodesy and Geomatics Engineering Laboratory, Mineral Resources Engineering Department)
The Gavdos facility is, the only Cal/Val site in the world, situated under a crossing point of the Jason orbits and adjacent to the orbits of Envisat, and subsequently of the future SARAL/Altika. The infrastructure of the permanent Cal/Val facility on Gavdos includes tide gauges, 10 permanent Global Navigation Satellite System (GNSS) receivers in Gavdos and Crete, meteorological instruments, a DORIS satellite beacon, an electronic microwave transponder (a new one under testing and calibration at the European Space Agency in the Netherlands and ready to be deployed), communications links for the transmission of data, etc. To further improve the operational capabilities of the Gavdos facility, two more calibration sites have been developed at RDK1 (Jason pass) and CRS1 (cross-over of Sentinel-3 A&B, south west Crete), both in the mainland of Crete. Given the importance of these Cal/Val facilities in Gavdos and Crete Cal/Val, both from the scientific point of view and as a model satellite research centre, the continuation of its operation becomes vital.
The objectives of this proposed research are:
These objectives are fully aligned with the goals of this OST-ST joint research announcement. This Gavdos/Crete Cal/Val experiment includes the estimation of the satellite altimeter bias, as well as monitoring its drifts and calibrating its radiometer and ionosphere dealys with a permanent network of 10 GNSS sites. At Gavdos, this has been done using two independent techniques. The first one involves direct comparisons between the sea-surface height, measured by the altimeter, and the absolute sea level established by the Cal/Val facility. The second one concerns calibration with the microwave transponder. The benefit of using two independent procedures for calibration, as well as for inter-calibration of different missions can be accomplished with the Gavdos/Crete Cal/Val facility.