On-orbit calibration of the Naval EarthMap Observer (NEMO) coastal ocean imaging spectrometer (COIS)

Abstract

ABSTRACT Production of science or Naval products from hyperspectral data requires the careful calibration of thesensor and the validation of the algorithms to demonstrate that they produce the correct products at therequired accuracy. Thus a key part of the Navy's Hyperspectral Remote Sensing Technology Program is the maintenance of accurate calibration for the Naval EarthMap Observer (NEMO) spacecraft's Coastal Ocean Imaging Spectrometer (COTS) during the lifetime of the spacecraft. On-Orbit COTS is calibrated in three ways: Moon imaging, using on-board calibration lamps, and imaging of wellcharacterized ocean and land scenes. The primary standard for COTS on-orbit calibration will be monthly imaging of the moon. The approach is similar to that used in NASA's SeaWiFS and MODISprograms, with the added complication that COTS images the Moon surface at much higher resolution than the NASA 1 km resolution sensors. On-board calibration lamps will not provide absolute calibration, but will be used to provide a stability check as frequently as once per orbit. Tmaging theknown reflectance land and open ocean sites will provide a data set for validating the calibration andatmospheric correction against measured surface reflectances. As an additional check COTS will becross-calibrated with two well calibrated aircraft sensors, NRL's Ocean PHILLS and NASA's AVTRTS,which will under-fly COTS and image the same ocean and land scenes.