Absolute Calibration of SARAL/AltiKa in Kavaratti During its Initial Calibration-Validation Phase

Abstract

The Kavaratti calibration-validation site in India at Lakshadweep Sea has been improved to carry out absolute calibration of SARAL/AltiKa altimeter. This site is augmented with a down-looking radar gauge and a permanent GPS receiver. The Kavaratti Island is located near a repeating ground track of SARAL/AltiKa and ∼12 km away from the point of closest measurement of Jason-2, SARAL/AltiKa crossover point. Additionally, the altimeter and radiometer footprints do not experience any land contamination. This article aims at presenting the initial calibration-validation results over cycles 001-011 of AltiKa. The absolute sea surface height bias has been found to be −48 mm at Kavaratti calibration site. In this preliminary study the effect of environmental variables such as winds and pressure are not considered in calculations.

Keywords:

• Absolute
• AltiKa
• calibration
• GPS
• Kavaratti
• tide gauge

Acknowledgements

The authors thank Director DST–Kavaratti and the project staff for their support and cooperation. Sincere thanks to Mr. Calzas and Mr. Guillot, CNRS for conducting GPS buoy experiment at Kavaratti Island. Thanks to AVISO for providing mean dynamic topography data sets.