Atmospheric Correction for Ocean Retrievals from the PACE Observatory
NASA's Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) is a climate continuity mission that aims to extend the high-quality ocean ecological and biogeochemical, clouds, and aerosols data records begun by NASA in the 1990s. The PACE observatory will host three instruments. The primary instrument is the Ocean Color Instrument (OCI), which is being developed at the Goddard Space Flight Center (GSFC) and is a hyperspectral scanning radiometer that measures the light from 320 to 890 nm at 2.5-nm spectral resolution and seven discrete short-wave infrared (SWIR) channels: 940, 1,039, 1,250, 1,378, 1,615, 2,130, and 2,260 nm. The two other instruments, the Hyper-Angular Rainbow Polarimeter 2 (HARP2) and the Spectro-Polarimeter for Exploration (SPEXone), are aimed at studying aerosols and clouds and are multi-angular polarimeters (MAPs) developed and contributed by external partners. To employ OCI's unprecedented hyperspectral capabilities for ocean applications, an accurate atmospheric correction (AC) process to remove the atmospheric path and ocean surface reflection signal needs to be developed. This AC process needs to perform beyond the current algorithm designed for multispectral sensors. The OCI algorithm will rely on the proven heritage AC capabilities but extended to hyperspectral data and will rely on the SWIR channels dedicated for coastal and inland waters AC. The multiband AC (MBAC) algorithm will improve the aerosol signal determination, reduce uncertainties, and can be adaptively weighted to the strongly absorbing SWIR channels in order to enable improved ocean color retrievals in coastal waters. In addition to AC that solely relies upon OCI capabilities, the MAPs will provide information about more complex aerosols to better constrain the AC for OCI.
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Author(s): Ibrahim, A.