Space-based hyperspectral imaging spectroradiometer for coastal studies

Resolving the complexity of coastal and estuarine waters requires high spatial resolution, hyperspectral imaging spectroradiometry. Hyperspectral measurements also provide capability for measuring bathymetry and bottom types in optically shallow water and for detailed cross calibration with other instruments in polar and geosynchronous orbit. This paper reports on recent design studies for a hyperspectral Coastal Imager (CI - pronounced "sea") that measures key data products from sun synchronous orbit. These products include water-leaving radiances in the near-ultraviolet, visible and near-infrared for separation of absorbing and scattering coastal water constituents and for calculation of chlorophyll fluorescence. In addition, CI measures spectral radiances in the near-infrared and shortwave infrared for atmospheric corrections while also measuring cloud radiances without saturation to enable more accurate removal of instrument stray light effects. CI provides contiguous spectral coverage from 380 to 2500 nm at 20 m GIFOV at nadir across 5000 + km(2) scenes with spectral sampling, radiometric sensitivity and calibration performance needed to meet the demanding requirements of coastal imaging. This paper describes the CI design, including concepts of operation for data collection, calibration (radiometric, spectral and spatial), onboard processing and data transmission to Earth. Performance characteristics for the instrument and all major subsystems including the optics, focal plane assemblies, onboard calibration, onboard processing and thermal subsystem are presented along with performance predictions for instrument sensitivity and calibration. Initial estimates of size, mass, power and data rate are presented.