Validation of Satellite Ocean Color Primary Products at Optically Complex Coastal Sites: Northern Adriatic Sea, Northern Baltic Proper and Gulf of Finland

• Published in: Remote Sensing of Environment
• Main Authors: ZIBORDI Giuseppe, BERTHON Jean-Francois, MELIN Frederic, D'ALIMONTE Davide, KAITALA Seppo
• Language: English
• Published: ELSEVIER SCIENCE INC 2009
• Subjects: Aerosol Robotic Network
• Online Access: https://publications.jrc.ec.europa.eu/repository/handle/JRC50864; https://doi.org/10.1016/j.rse.2009.07.013

The study presents and discusses the application of in situ data from the Ocean Color component of the Aerosol Robotic Network (AERONET-OC) to assess primary remote sensing products from Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide-Field-of-view Sensor (SeaWiFS). Three AERONET-OC European coastal sites exhibiting different atmospheric and marine optical properties were considered for the study: the Acqua Alta Oceanographic Tower (AAOT) in the northern Adriatic Sea exhibiting Case-1 and Case-2 moderately sediment dominated waters; and, the Gustaf Dalen Lighthouse Tower (GDLT) in the northern Baltic Proper and the Helsinki Lighthouse Tower (HLT) in the Gulf of Finland, both characterized by Case-2 highly yellow substance dominated waters. The analysis of MODIS derived normalized water-leaving radiance at 551 nm, LWN(551) has shown relatively good results for all sites with uncertainties of the order of 10% and biases ranging from -1 to -4%. Larger uncertainty and bias have been observed at 443 nm for the AAOT (i.e., 18 and -7%, respectively). At the same center-wavelength, results for GDLT and HLT have exhibited much larger uncertainties (i.e., 56 and 67%, respectively) and biases (i.e., 18 and 25%, respectively), which undermine the possibility of presently using remote sensing LWN data at the blue center-wavelengths for bio-optical investigations in the Baltic Sea. An evaluation of MODIS derived aerosol optical thickness, �a, has shown uncertainties and biases of the order of tens of percent increasing with wavelength at all sites. For AAOT, GDLT and HLT, �a(869) has shown an overestimate of 71, 101 and 91%, respectively. This result indicates the lack of an appropriate aerosol model for the atmospheric correction process, or the need of applying a vicarious calibration factor at the 869 nm center-wavelength to remove the effects of uncertainties in the atmospheric optical model and the space sensor radiometric calibration. Similar results have been obtained from the analysis of ...