Wednesday, 9 January 2013
Exhibit Hall 3 (Austin Convention Center)
Handout (2.0 MB)
Retrieving the normalized water leaving radiance, which is subsequently used in the estimation of the bio-optical properties of ocean water, from the ocean color (OC) satellite images requires the accurate estimation and removal of atmospheric perturbation effects from the top of atmosphere radiance values recorded by the satellite sensor. This is a challenging task, especially for coastal water areas where overall optical complexity of the atmospheric-water system tends to be particularly high. Ultimately, the retrieved water-leaving signal, which carries information on water optical properties and water composition, is not error free and its reliability needs to be evaluated and validated against high quality field measurements. As part of the VIIRS sensor calibration and validation efforts, our group has been continuously monitoring the validity of the VIIRS's OC and atmospheric data stream through time series in-situ data acquired at our Long Island Sound Coastal Observatory (LISCO) platform, which was established two years ago to support multi- and hyper-spectral validation activities of present and future OC satellite missions for coastal water environments. The multispectral measurements at LISCO are part of the SeaPRISM NASA AERONET OC Network which was designed to support long-term satellite ocean color investigations. In addition to the multi-spectral SeaPRISM measurements, LISCO expands observational capabilities with a HyperSAS instrument suite for continuous monitoring and assessment of the hyperspectral and polarized properties of coastal waters. This present study primarily addresses evaluations of VIIRS sensor's performance in retrieving OC data from typical coastal water environments, by carrying out time-series and match-up comparisons between in-situ and satellite retrieved normalized water leaving radiance, aerosol optical thickness data, and the impact of aerosol mode selection at the LISCO location. Initial time-series match-up comparisons carried out for an 8 months period (January to August, 2012) show that VIIRS data exhibits strong temporal and statistical agreements with LISCO data demonstrating the VIIRS sensor's potential for enhanced coastal water remote sensing, and confirms the suitability of LISCO's as a coastal validation site. In addition, VIIRS's retrieval performances in coastal water conditions are statistically compared to those of heritage OC satellite missions, specifically the Moderate Resolution Imaging Spectrometer (MODIS) sensor aboard the Aqua satellite and Medium Resolution Imaging Spectrometer (MERIS) aboard the ENVISAT satellite, based on time-series in-situ data from LISCO's entire (almost 3 year) period of operations.
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