TY - JOUR
T1 - Spectral Interdependence of Remote-sensing Reflectance and its Implications on the Design of Ocean Color Satellite Sensors
AU - Lee, Zhongping
AU - Shang, Shaoling
AU - Hu, Chuanmin
AU - Zibordi, Giuseppe
PY - 2014/1/1
Y1 - 2014/1/1
N2 - Using 901 remote-sensing reflectance spectra (Rrs(λ),sr−1">��rs(��),sr−1Rrs(λ),sr−1 , λ">��λ from 400 to 700 nm with a 5 nm resolution), we evaluated the correlations of Rrs(λ)">��rs(��)Rrs(λ) between neighboring spectral bands in order to characterize (1) the spectral interdependence of Rrs(λ)">��rs(��)Rrs(λ) at different bands and (2) to what extent hyperspectral Rrs(λ)">��rs(��)Rrs(λ) can be reconstructed from multiband measurements. The 901 Rrs">��rsRrs spectra were measured over a wide variety of aquatic environments in which water color varied from oceanic blue to coastal green or brown, with chlorophyll-a concentrations ranging from ∼0.02">∼0.02∼0.02 to >100 mg m−3">>100 mg m−3>100 mg m−3 , bottom depths from ∼1 m">∼1 m∼1 m to >1000 m">>1000 m>1000 m , and bottom substrates including sand, coral reef, and seagrass. The correlation coefficient of Rrs(λ)">��rs(��)Rrs(λ) between neighboring bands at center wavelengths λk">����λk and λl">����λl , rΔλ(λk,λl)">��Δ��(����,����)rΔλ(λk,λl) , was evaluated systematically, with the spectral gap (Δλ=λl−λk">Δ��=����−����Δλ=λl−λk ) changing between 5, 10, 15, 20, 25, and 30 nm, respectively. It was found that rΔλ">��Δ��rΔλ decreased with increasing Δλ">Δ��Δλ , but remained >0.97">>0.97>0.97 for Δλ≤20 nm">Δ��≤20 nmΔλ≤20 nm for all spectral bands. Further, using 15 spectral bands between 400 and 710 nm, we reconstructed, via multivariant linear regression, hyperspectral Rrs(λ)">��rs(��)Rrs(λ) (from 400 to 700 nm with a 5 nm resolution). The percentage difference between measured and reconstructed Rrs">��rsRrs for each band in the 400–700 nm range was generally less than 1%, with a correlation coefficient close to 1.0. The mean absolute error between measured and reconstructed Rrs">��rsRrs was about 0.00002 sr−1">0.00002 sr−10.00002 sr−1 for each band, which is significantly smaller than the Rrs">��rsRrs uncertainties from all past and current ocean color satellite radiometric products. These results echo findings of earlier studies that Rrs">��rsRrs measurements at ∼15">∼15∼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.
AB - Using 901 remote-sensing reflectance spectra (Rrs(λ),sr−1">��rs(��),sr−1Rrs(λ),sr−1 , λ">��λ from 400 to 700 nm with a 5 nm resolution), we evaluated the correlations of Rrs(λ)">��rs(��)Rrs(λ) between neighboring spectral bands in order to characterize (1) the spectral interdependence of Rrs(λ)">��rs(��)Rrs(λ) at different bands and (2) to what extent hyperspectral Rrs(λ)">��rs(��)Rrs(λ) can be reconstructed from multiband measurements. The 901 Rrs">��rsRrs spectra were measured over a wide variety of aquatic environments in which water color varied from oceanic blue to coastal green or brown, with chlorophyll-a concentrations ranging from ∼0.02">∼0.02∼0.02 to >100 mg m−3">>100 mg m−3>100 mg m−3 , bottom depths from ∼1 m">∼1 m∼1 m to >1000 m">>1000 m>1000 m , and bottom substrates including sand, coral reef, and seagrass. The correlation coefficient of Rrs(λ)">��rs(��)Rrs(λ) between neighboring bands at center wavelengths λk">����λk and λl">����λl , rΔλ(λk,λl)">��Δ��(����,����)rΔλ(λk,λl) , was evaluated systematically, with the spectral gap (Δλ=λl−λk">Δ��=����−����Δλ=λl−λk ) changing between 5, 10, 15, 20, 25, and 30 nm, respectively. It was found that rΔλ">��Δ��rΔλ decreased with increasing Δλ">Δ��Δλ , but remained >0.97">>0.97>0.97 for Δλ≤20 nm">Δ��≤20 nmΔλ≤20 nm for all spectral bands. Further, using 15 spectral bands between 400 and 710 nm, we reconstructed, via multivariant linear regression, hyperspectral Rrs(λ)">��rs(��)Rrs(λ) (from 400 to 700 nm with a 5 nm resolution). The percentage difference between measured and reconstructed Rrs">��rsRrs for each band in the 400–700 nm range was generally less than 1%, with a correlation coefficient close to 1.0. The mean absolute error between measured and reconstructed Rrs">��rsRrs was about 0.00002 sr−1">0.00002 sr−10.00002 sr−1 for each band, which is significantly smaller than the Rrs">��rsRrs uncertainties from all past and current ocean color satellite radiometric products. These results echo findings of earlier studies that Rrs">��rsRrs measurements at ∼15">∼15∼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.
UR - https://digitalcommons.usf.edu/msc_facpub/1925
UR - https://doi.org/10.1364/AO.53.003301
U2 - 10.1364/AO.53.003301
DO - 10.1364/AO.53.003301
M3 - Article
C2 - 24922219
VL - 53
JO - Applied Optics
JF - Applied Optics
ER -