Abstract
Optical closure is assessed between measured and simulated remote-sensing reflectance (Rrs) using Hydrolight radiative transfer code for five data sets that included a broad range of both Case I and Case II water types. Model-input inherent optical properties (IOPs) were the absorption coefficient determined with a WET Labs ac9 and the volume scattering function (VSF) determined with a custom in situ device called MASCOT. Optimal matchups were observed using measured phase functions and reflective tube absorption measurements corrected using a scattering error independently derived from VSF measurements. Absolute bias (δ) for simulations compared to measured Rrs was 20% for the entire data set, and 17% if a relatively shallow station with optical patchiness was removed from the analysis. Approximately half of this δ is estimated to come from uncertainty in radiometric measurements of Rrs, with the other half arising from combined uncertainties in IOPs, radiative transfer modeling, and related assumptions. For exercises where such δ can be tolerated, IOPs have the potential to aid in ocean color validation. Overall, δ was roughly consistent with the sum of uncertainties derived from associated measurements, although larger deviations were observed in several cases. Applying Fournier-Forand phase functions derived from particulate backscattering ratios according to Mobley et al. [Appl. Opt. 41, 1035 (2002)] resulted in overall δ that was almost as good (23%) as simulations using measured phase functions. Possibilities for improving closure assessments in future studies are discussed.
Original language | English (US) |
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Pages (from-to) | 130-146 |
Number of pages | 17 |
Journal | Applied Optics |
Volume | 56 |
Issue number | 1 |
DOIs | |
State | Published - Jan 1 2017 |
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Engineering (miscellaneous)
- Electrical and Electronic Engineering