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|Title:||Spectral interdependence of remote-sensing reflectance and its implications on the design of ocean color satellite sensors|
|Authors:||LEE Zhongping; SHANG Shaoling; HU Chuanmin; ZIBORDI Giuseppe|
|Citation:||APPLIED OPTICS vol. 53 no. 15 p. 3301-3310|
|Publisher:||OPTICAL SOC AMER|
|Type:||Articles in periodicals and books|
|Abstract:||Using 901 remote-sensing reflectance spectra (Rrs(λ), sr-1, from 400 to 700 nm with a 5-nm resolution), we evaluated the correlations of Rrs(λ) between neighboring spectral bands in order to characterize 1) the spectral interdependence of Rrs(λ) at different bands and 2) to what extent can hyperspectral Rrs(λ) be re-constructed from multi-band measurements. The 901 Rrs spectra were measured over a wide variety of aquatic environments where water color varied from oceanic blue to coastal green or brown, with chlorophyll-a concentrations ranging from ~0.02 to >100 mg m-3, bottom depths from ~1 m to > 1000 m, and bottom substrates including sand, coral reef, and seagrass. The correlation coefficient of Rrs(λ) between neighboring bands (λk and λl), rΔλ(λk,λl), was evaluated systematically, with the spectral gap (Δλ= λl - λk) changing from 5, 10, 15, 20, 25, to 30 nm, respectively. It was found that rΔλ decreased with increasing Δλ, but remained > 0.97 for Δλ ≤ 20 nm for all spectral bands. Further, using 15 spectral bands between 400 and 710 nm, we re-constructed, via multi-variant linear regression, hyperspectral Rrs(λ) (from 400 to 700 nm with a 5-nm resolution). The coefficient of variation between measured and re-constructed Rrs for each band in the 400-700 nm range was generally less than 2%, with a correlation coefficient close to 1.0. The mean absolute error between measured and re-constructed Rrs was about 0.00005 sr-1 for each band, which is significantly smaller than the Rrs uncertainties from all past and current ocean color satellite measurements. These results echo findings of earlier studies that Rrs measurements at ~15 spectral bands in the visible domain can provide nearly identical spectral information as with hyperspectral (contiguous bands at 5-nm spectral resolution) measurements. Such results provide insights for data storage and handling of large volume hyperspectral data as well as for the design of future ocean color satellite sensors.|
|JRC Directorate:||Sustainable Resources|
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