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Exploring the limits for sky and sun glint correction of hyperspectral above-surface reflectance observations



Details

  • Journal Title:
    Applied Optics
  • Personal Author:
  • NOAA Program & Office:
    CESSRST (Cooperative Science Center for Earth System Sciences and Remote Sensing Technologies)
  • Description:
    Above-surface radiance observations of water need to be corrected for reflections on the surface to derive reflectance. The three-component glint model (3C) [Opt. Express 25, A742 (2017) [CrossRef] ] was developed to spectrally resolve contributions of sky and sun glint to the surface-reflected radiance signal (), and for observations recorded at high wind speed and with fixed-position measurement geometries that frequently lead to significant sun glint contributions. Performance and limitations of 3C are assessed for all relevant wind speeds, clear sky atmospheric conditions, illumination/viewing geometries, and sun glint contamination levels. For this purpose, a comprehensive set of () spectra was simulated with a spectrally resolved sky radiance distribution model and Cox–Munk wave slope statistics. Reflectances were also derived from an extensive four-year data set of continuous above-surface hyperspectral observations from the Long Island Sound Coastal Observatory, allowing to corroborate 3C processing results from simulations and measurements with regard to sky and sun glint contributions. Simulation- and measurement-derived () independently indicate that spectral dependencies of the sky light distribution and sun glint contributions may not be neglected for observations recorded at wind speeds exceeding 4/, even for sun glint-minimizing measurement geometries (Sun-sensor azimuth angle Δ=90−135°). These findings are in accordance with current measurement protocols for satellite calibration/validation activities. In addition, it is demonstrated that 3C is able to reliably derive water reflectance for wind speeds up to 8 m/s and Δ>20°.
  • Keywords:
  • Source:
    Appl. Opt. 59(9): 2942-2954
  • DOI:
  • Document Type:
    Journal Article
  • Funding:
    Grant no. NA16SEC4810008
  • Rights Information:
    Accepted Manuscript
  • Compliance:
    Submitted
  • Main Document Checksum:
    urn:sha256:806e8bb338d58714ca6509bc2b334e8a95f369bb59db03421e1e04cf6b7e73fa
  • Download URL:
  • File Type:
    Filetype[PDF - 1.50 MB ]
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