Evaluation of Atmospheric Correction Algorithms for Sentinel-2-MSI and Sentinel-3-OLCI in Highly Turbid Estuarine Waters

KEUKELAERE, LIESBETH DE; DOXARAN, DAVID; RENOSH, PANNIMPULLATH REMANAN; GOSSN, JUAN IGNACIO

Remote Sensing

MDPI

Lugar: Basilea; Año: 2020 vol. 12

The present study assesses the performance of state-of-the-art atmospheric correction(AC) algorithms applied to Sentinel-2-MultiSpectral Instrument (S2-MSI) and Sentinel-3-Ocean andLand Color Instrument (S3-OLCI) data recorded over moderately to highly turbid estuarine waters,considering the Gironde Estuary (SW France) as a test site. Three spectral bands of water-leavingreflectance (Rhow) are considered: green (560 nm), red (655 or 665 nm) and near infrared (NIR)(865 nm), required to retrieve the suspended particulate matter (SPM) concentrations in clear tohighly turbid waters (SPM ranging from 1 to 2000 mg/L). A previous study satisfactorily validatedAcolite short wave infrared (SWIR) AC algorithm for Landsat-8-Operational Land Imager (L8-OLI)in turbid estuarine waters. The latest version of Acolite Dark Spectrum Fitting (DSF) is tested hereand shows very good agreement with Acolite SWIR for OLI data. L8-OLI satellite data corrected foratmospheric effects using Acolite DSF are then used as a reference to assess the validity of atmosphericcorrections applied to other satellite data recorded over the same test site with a minimum timedifference. Acolite DSF and iCOR (image correction for atmospheric effects) are identified as thebest performing AC algorithms among the tested AC algorithms (Acolite DSF, iCOR, Polymer andC2RCC (case 2 regional coast color)) for S2-MSI. Then, the validity of six different AC algorithms(OLCI Baseline Atmospheric Correction (BAC), iCOR, Polymer, Baseline residual (BLR), C2RCC-V1and C2RCC-V2) applied to OLCI satellite data is assessed based on comparisons with OLI and/orMSI Acolite DSF products recorded on a same day with a minimum time lag. Results show that all theAC algorithms tend to underestimate Rhow in green, red and NIR bands except iCOR in green and redbands. The iCOR provides minimum differences in green (slope = 1.0 ± 0.15, BIAS = 1.9 ± 4.5% andmean absolute percentage error (MAPE) = 12 ± 5%) and red (slope = 1.0 ± 0.17, BIAS = −9.8 ± 9%and MAPE = 28 ± 20%) bands with Acolite DSF products from OLI and MSI data. For the NIR band,BAC provides minimum differences (slope = 0.7 ± 0.13, BIAS = −33 ± 17% and MAPE = 55 ± 20%)with Acolite DSF products from OLI and MSI data. These results based on comparisons betweenalmost simultaneous satellite products are supported by match-ups between satellite-derived andfield-measured SPM concentrations provided by automated turbidity stations. Further validation ofsatellite products based on rigorous match-ups with in-situ Rhow measurements is still required inhighly turbid waters