Global sensitivity analysis of coupled SCOPE-6S model

Research output: Contribution to conferenceAbstract

Abstract

We quantified the relative importance of different Sentinel-3 bands for retrieval of plant traits and atmospheric composition parameters by coupling a land surface (SCOPE) and an atmospheric radiative transfer model (S6). For this purpose, we simulated top of atmosphere (TOA) radiance of the two instruments on-board of Sentinel-3 (Ocean and Land Colour Instrument, OLCI and Sea and Land Surface Temperature Radiometer, SLSTR), and carried out a sensitivity analysis of these radiances to vegetation, soil and atmospheric parameters. The SCOPE model parameters included in the sensitivity analysis were leaf traits (chlorophylls, Cab; carotenoids, Cca; anthocyanins, Cant; water thickness, Cw; dry matter content, Cdm; senescent material, Cs; leaf mesophyll structure parameter, N), canopy traits (leaf area index, LAI; leaf inclination distribution functions parameters, LIDFa, LIDFb) and soil traits (brightness, B; soil moisture content, SMC). Top of canopy reflectance simulated with SCOPE was propagated through the atmosphere to produce TOA radiance. The atmospheric propagation was carried out with 6S using a “Continental” aerosol distribution profile scaled to provided aerosol optical thickness values (AOT). Water and ozone values were used to scale “us standard 62” atmospheric profile. Three parameters of 6S model (AOT, water and ozone) were used in the sensitivity analysis. TOA radiance values were integrated with the sensor response functions of OLCI and SLSTR. The global sensitivity analysis was done against 15 parameters with Saltelli sampling and Sobol method.
The results demonstrated that LAI and soil brightness had high impact on all the bands of both OLCI and SLSTR instruments. As expected, chlorophyll content significantly influenced bands Oa06-11 (561-709 nm) and S1-2 (554, 659 nm) and water content (both leaf and atmospheric) Oa20-21 (941, 1025 nm) and S4-6 (1375, 1613, 2256 nm). Bands beyond 750 nm were sensitive to dry matter content. The rest of the parameters showed low impact on TOA radiance with total sensitivity index close to 0.05, whereas N parameter did not demonstrate its importance at all. The next step in the analysis will be the inclusion of the SLSTR bands in the thermal domain S7-9 (3.7, 10.8, 12.0 um). The results will be used for the development of a retrieval algorithm of land surface properties from Sentinel-3.

The project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 721995.
Original languageEnglish
Pages20
Number of pages1
Publication statusPublished - Mar 2019

Keywords

  • SCOPE model
  • Sentinel-3
  • global sensitivity analysis (GSA)
  • remote sensing

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