Comparison of Above-Water Seabird and TriOS Radiometers along an Atlantic Meridional Transect

Alikas, K, Vabson, V, Ansko, I, Tilstone, GH, Dall’Olmo, G, Nencioli, F, Vendt, R, Donlon, C and Casal, T 2020 Comparison of Above-Water Seabird and TriOS Radiometers along an Atlantic Meridional Transect. Remote Sensing, 12 (10). 1669.

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The Fiducial Reference Measurements for Satellite Ocean Color (FRM4SOC) project has carried out a range of activities to evaluate and improve the state-of-the-art in ocean color radiometry. This paper described the results from a ship-based intercomparison conducted on the Atlantic Meridional Transect 27 from 23rd September to 5th November 2017. Two different radiometric systems, TriOS-Radiation Measurement Sensor with Enhanced Spectral resolution (RAMSES) and Seabird-Hyperspectral Surface Acquisition System (HyperSAS), were compared and operated side-by-side over a wide range of Atlantic provinces and environmental conditions. Both systems were calibrated for traceability to SI (Système international) units at the same optical laboratory under uniform conditions before and after the field campaign. The in situ results and their accompanying uncertainties were evaluated using the same data handling protocols. The field data revealed variability in the responsivity between TRiOS and Seabird sensors, which is dependent on the ambient environmental and illumination conditions. The straylight effects for individual sensors were mostly within ±3%. A near infra-red (NIR) similarity correction changed the water-leaving reflectance (ρw) and water-leaving radiance (Lw) spectra significantly, bringing also a convergence in outliers. For improving the estimates of in situ uncertainty, it is recommended that additional characterization of radiometers and environmental ancillary measurements are undertaken. In general, the comparison of radiometric systems showed agreement within the evaluated uncertainty limits. Consistency of in situ results with the available Sentinel-3A Ocean and Land Color Instrument (OLCI) data in the range from (400…560) nm was also satisfactory (-8% < Mean Percentage Difference (MPD) < 15%) and showed good agreement in terms of the shape of the spectra and absolute values.

Item Type: Publication - Article
Additional Information. Not used in RCUK Gateway to Research.: Tartu University, Tartu Observatory, Observatooriumi 1, 61602 Tartu, Estonia; (V.V.); (I.A.); (R.V.) 2. Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, UK; (G.T.); (G.D.); (F.N.) 3. European Space Agency, 2201 AZ Noordwijk, The Netherlands; (C.D.); (T.C.) * Correspondence:
Additional Keywords: ocean color; remote sensing; radiometry; TriOS RAMSES; Seabird HyperSAS; measurement uncertainty; validation; Sentinel-3 OLCI; Copernicus
Divisions: Plymouth Marine Laboratory > National Capability categories > Atlantic Meridional Transect
Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications
Depositing User: S Hawkins
Date made live: 02 Jun 2020 10:02
Last Modified: 02 Jun 2020 10:02

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