Post-launch calibration of Ocean Colour Monitor 2 using Kavaratti CAL-VAL site observations

Oceansat-2 mission is envisaged to provide continuity of services for the operational users of Ocean Colour Monitor (OCM) data as well as enhance the application potential in other areas. It was successfully launched by PSLV-C14 flight on 23 September 2009 from Shriharikota launch pad. It carried three payload instruments, viz. OCM 2, a Ku-band scatterometer (OSCAT) and a Radio Occultation Sounder for Atmosphere (ROSA) which has been developed by the Italian Space Agency. A controlled calibration and validation site is envisaged in southeast Arabian Sea to monitor the OCM 2 sensor stability owing to its post-launch performance and ageing-related problems in orbit. This site measures hyper-spectral optical radiances (both in air and underwater), meteorological parameters and CIMEL 318 sun-photometer for sun and sky radiation in automated mode. All these datasets are received from the site via satellite communication. These measurements are analysed along with top-of-the-atmosphere (TOA) radiance measured by OCM 2 sensor. The OCM 2 sensor performance is monitored against the radiance computed at TOA through a forward radiative transfer model for the period spanning from 23 September 2009 to 24 April 2010.