In situ autonomous optical radiometry measurements for satellite ocean color validation in the Western Black Sea

• Main Authors: G. Zibordi, F. Mélin, J.-F. Berthon, M. Talone
• Format: Article
• Language: English
• Published: Copernicus Publications 2015-03-01
• Series: Ocean Science
• Online Access: http://www.ocean-sci.net/11/275/2015/os-11-275-2015.pdf

The accuracy of primary satellite ocean color data products from the Moderate Resolution Imaging Spectroradiometer on-board Aqua (MODIS-A) and the Visible/Infrared Imager/Radiometer Suite (VIIRS) is investigated in the Western Black Sea using in situ measurements from the Gloria site included in the ocean color component of the Aerosol Robotic Network (AERONET-OC). The analysis is also extended to an additional well-established AERONET-OC site in the northern Adriatic Sea characterized by optically complex coastal waters exhibiting similarities to those observed at the Gloria site. Results from the comparison of normalized water-leaving radiance <I>L</I>_WN indicate biases of a few percent between satellite-derived and in situ data at the center wavelengths relevant for the determination of chlorophyll <I>a</I> concentrations (443–547 nm, or equivalent). Remarkable is the consistency between the annual cycle determined with time series of satellite-derived and in situ <I>L</I>_WN ratios at these center wavelengths. Contrarily, the differences between in situ and satellite-derived <I>L</I>_WN are pronounced at the blue (i.e., 412 nm) and red (i.e., 667 nm, or equivalent) center wavelengths, confirming difficulties in confidently applying satellite-derived radiometric data from these spectral regions for quantitative analysis in optically complex waters.