The 2013 Ibiza Calibration Campaign of Jason-2 and SARAL Altimeters

Abstract

This study presents the results of the 2013 Ibiza (Western Mediterranean) calibration campaign of Jason-2 and SARAL altimeters. It took place from 14 to 16 September 2013 and comprised two phases: the calibration of the GNSS (Global Navigation Satellite System) buoys to estimate the antenna height of each of them and the absolute calibration to estimate the altimeter bias (i.e., the difference of sea level measured by radar altimetry and GNSS). The first one was achieved in the Ibiza harbor at a close vicinity of the Ibiza tide gauge and the second one was performed at ∼ 40 km at the northwest of Ibiza Island at a crossover point of Jason-2 and SARAL nominal groundtracks. Five buoys were used to delineate the crossover region and their measurements interpolated at the exact location of each overflight. The overflights occurred two consecutive days: 15 and 16 September 2013 for Jason-2 and SARAL, respectively. The GNSS data were processed using precise point positioning technique. The biases found are of (−0.1 ± 0.9) and (−3.1 ± 1.5) cm for Jason-2 and SARAL, respectively.

Keywords:

• satellite altimetry
• calibration
• GNSS buoys
• tide gauge

Acknowledgements

We acknowledge the Spanish Navy (Armada Española) for its support and particularly T.N. Paredes, Commanding Officer of the Toralla patrol ship, and his crew, for the excellent job made during the survey. We thank the Real Instituto y Observatorio de la Armada (ROA) for its support. We also thank the CTOH/LEGOS-OMP, France, for providing the altimetry dataset used in this study.

Funding

This study was funded under the Spanish National R+D+i program (ref: CGL2009–13435/CLI). This study takes part of the OSTST (CNES-NASA-NOAA-EUMETSAT) project “From Ocean to inland waters Altimetry Monitoring” (FOAM, PI P. Bonnefond).