In situ determination of the remote sensing reflectance: an inter-comparison

• Main Authors: G. Zibordi, K. Ruddick, I. Ansko, G. Moore, S. Kratzer, J. Icely, A. Reinart
• Format: Article
• Language: English
• Published: Copernicus Publications 2012-08-01
• Series: Ocean Science
• Online Access: http://www.ocean-sci.net/8/567/2012/os-8-567-2012.pdf

Inter-comparison of data products from simultaneous measurements performed with independent systems and methods is a viable approach to assess the consistency of data and additionally to investigate uncertainties. Within such a context the inter-comparison called <I>Assessment of In Situ Radiometric Capabilities for Coastal Water Remote Sensing Applications</I> (ARC) was carried out at the Acqua Alta Oceanographic Tower in the northern Adriatic Sea to explore the accuracy of in situ data products from various in- and above-water optical systems and methods. Measurements were performed under almost ideal conditions, including a stable deployment platform, clear sky, relatively low sun zenith angles and moderately low sea state. Additionally, all optical sensors involved in the experiment were inter-calibrated through absolute radiometric calibration performed with the same standards and methods. Inter-compared data products include spectral water-leaving radiance <I>L</I><sub>w</sub> (λ), above-water downward irradiance <I>E</I><sub>d</sub>(0<sup>+</sup>,λ) and remote sensing reflectance <I>R</I><sub>rs</sub>(λ). Data products from the various measurement systems/methods were directly compared to those from a single reference system/method. Results for <I>R</I><sub>rs</sub>(λ) indicate spectrally averaged values of relative differences comprised between −1 and +6%, while spectrally averaged values of absolute differences vary from approximately 6% for the above-water systems/methods to 9% for buoy-based systems/methods. The agreement between <I>R</I><sub>rs</sub>(λ) spectral relative differences and estimates of combined uncertainties of the inter-compared systems/methods is noteworthy.