Sensor calibration of the Ocean Color Imager

Ocean Color Imager (OCI) aboard the ROCSAT-1 satellite is a multispectral i maging spectrometer for observing pigment distribution in low-latitude ocea ns. Sensor calibration contributes to characterization of its radiometric r esponse and to the development of a processing segment for recovering the a t-sensor radiance data. The major characteristics of OCI are presented, A m athematical model is developed to approximate the radiometric response of O CI and the corresponding parameters are initially identified by pre-flight calibration and adapted in-flight by a method of cross-platform calibration , The procedure of the pre-flight calibration is described and the results are shown, The cross-platform in-flight calibration compares the radiance d ata with those measured by the vicarious orbital sensor over the cross poin ts so that performance degradation or parameter change in OCI will not bias the sensor calibration. The difficulties in spectral matching, spatial res olution, sun-sensor geometry, radiometric compatibility, and data set regis tration have been considered. An algorithm of the parameter adaptation and data conversion has been developed and implemented.