A new paradigm for ocean color satellite calibration and validation:
accurate measurements of hyperspectral water leaving radiance from
autonomous profiling floats (HYPERNAV)
Abstract
Ocean color satellites require routine in-orbit verification and
vicarious calibration to maintain accuracy over the mission lifetime and
between satellites. The majority of vicarious calibration and validation
activities for ocean color satellites are carried out in areas of
uniform oceanic and atmospheric optical properties using in situ
radiometric data collected from fixed mooring installations or
oceanographic ships. These methods have limitations in spatial coverage
and in the cost of maintenance and operation. A spatially extensive
network of vicarious calibration match-up data points would aid in
reducing vicarious calibration uncertainty. To meet these needs, we have
developed a new approach to ocean color satellite vicarious calibration
and validation. Our system (HYPERNAV) combines accurate, reliable and
stable hyperspectral radiometric instruments with autonomous profiling
float technologies to provide a cost effective, unattended means for
vicarious calibration over periods of years in the open ocean. We
present data from laboratory and field experiments of the HYPERNAV
system used to characterize system performance and to quantify the
end-to-end radiance uncertainty budget. We present match-up comparisons
of HYPERNAV field data and coincident water leaving radiance
measurements from ocean color satellites, demonstrating the capabilities
of the system to provide new vicarious calibration paradigm for
ocean-color remote-sensing satellites.