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ProSoft User Manual 7.7
SAT-DN-00228
11.4.3.2 Refractive Index
Fresnel refractive index for seawater. A default value of 1.345 is used and can be
changed as a level 4 processing parameter.
11.4.4 Surface Remote Sensing Reflectance's
Remote sensing reflectance's RL(0+,λ) are calculated using:
Equation 22 Surface Remote Sensing Reflectance
(
(
LW 0 + , λ
RL 0 , λ =
Ed 0 + , λ
(
+
)
)
)
Ed(0+,λ) – denotes downwelling spectral irradiance measured just above the surface
(Es) or extrapolated through the surface Ed(0+). For Es the median of the time
series data is taken for each wavelength.
Lw(0+,λ) – denotes upwelling spectral radiance propagated through the surface.
The remote sensing reflectance's calculations produce several possible combinations
depending on the instrument configuration. Possible values include:
i. for Lu and Ed sensors Lu(0+,λ)/Ed(0+,λ)
ii. for Lu and Es sensors Lu(0+,λ)/Es(λ)
iii. for Ls and Es sensors Ls(0+,λ)/Es(λ)
Ed is extrapolated through the surface using:
Equation 23 Above Surface Ed(0+)
(
)
(
)
E d 0 + , λ = E d 0 − , λ (1 + α
)
α – Fresnel reflection albedo for irradiance from sun and sky. A default value of
0.043 is used and can be changed as a level 4 processing parameter.
Lw is calculated using:
Equation 24 Water Leaving Radiance
(
)
(
Lw 0 + , λ = Lu 0 − , λ
) 1 − ρ ( λ ,θ )
η
2
w
(λ )
ρ(λ,θ) - Fresnel reflectance index of seawater. Default value of 0.021 is used.
ηw(λ) - Fresnel refractive index of seawater. Default value of 1.345 is used.
11.4.5 Remote Sensing Reflectance Profile
Remote sensing reflectance profile is calculated as the ratio of upwelling radiance to
downwelling irradiance with changing depth. Only Lu is used for upwelling radiance and
Ed for downwelling irradiance.
Equation 25 Remote Sensing Reflectance Profile
Copyright © 2004 by Satlantic Incorporated
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