Bringing the Ocean into Finer Focus through the NASA COAST, HyspIRI, and OCEANIA Suborbital Missions
Thursday, 18 December 2014
High-quality ocean color measurements are needed to characterize water quality and phytoplankton functional types in the coastal zone. Accurate ocean color retrievals are often confounded by inadequacies in atmospheric correction. The recent NASA COAST, HyspIRI, and OCEANIA suborbital missions over Monterey Bay, CA have used novel instruments in a multi-sensor, multi-platform approach to collect above- and in-water measurements to better characterize ocean color through improvements in instrument dynamic range and attention to atmospheric correction. High-level objectives of these missions are to characterize the coastal ocean through end-to-end assessment of image acquisition, atmospheric correction, algorithm application, and sea-truth observations to improve vicarious calibration and validation of satellite ocean color products. We present results from COAST, HyspIRI, and OCEANIA to demonstrate the importance of coincident atmospheric and sea-truth measurements to improve atmospheric correction. Our specific objective was to conduct a sensitivity analysis of the atmospheric correction algorithm, Tafkaa, on Headwall Imaging Spectrometer data using input parameters of atmospheric aerosol optical depth spectra and column water vapor obtained from the Ames Airborne Tracking Sunphotometer (AATS-14) collected on the CIRPAS Twin Otter during COAST (2011). Use of the high dynamic-range, in-water Compact-Optical Profiling System (C-OPS) and above-water Coastal Airborne In-situ Radiometers (C-AIR) with matched wavelength channels enabled accurate observations of exact water-leaving radiance to use in validating imagery. Results from HyspIRI and OCEANIA (October 2013) flown on the NASA ER-2 and CIRPAS Twin Otter will be presented. Knowledge gained from these missions will improve vicarious calibration and validation of legacy (MODIS) and future (PACE & GEO-CAPE) satellite sensors to better characterize coastal ecosystems using ocean color observations.