Geoscience Reference
In-Depth Information
The first wave-dependent algorithms appeared in the work of Glazman and
Pilorz
8
and was further extended by Glazman and Greysukh.
11
However,
the inclusion of wave states on the computation of the MSS function
requires the selection and integration of a representative wave spectrum.
A detailed study of frequency spectra of ocean waves can be found
in Ref. 12.
3. Radiation Modeling
In this section, we will give a brief description of how we compute TOA
reflectance (the so-called remote sensing reflectance) which is routinely used
for a process known as atmospheric correction. Further details regard-
ing the process of atmospheric correction can be found in the work of
Gordon,
13
,
14
for applications to satellite imagery and ocean remote sensing
see for example Ref. 15.
3.1.
Top of the atmosphere reflectance
For remote sensing applications, usually the top of the atmosphere
reflectance (TOA) rather than the physical irradiance are commonly used,
therefore we write,
πL
F
0
cos(
θ
0
)
.
ρ
(
λ
)=
(5)
Here,
L
represents the up-welling radiance,
F
0
represents the extraterres-
trial solar irradiance (or solar flux) and
θ
0
represents the solar zenith angle.
The total reflectance
ρ
t
at a given wavelength
λ
is the sum of the contri-
butions from stratospheric gas (absorption and scattering), tropospheric
aerosols scattering and ocean surface processes like Sun glint, foam and
subsurface scattering diminished by the transmittance of the overlaying
atmospheric layers. In general, the TOA reflectance can be decomposed into
the following components, each of them defining a physical process inside
the atmosphere or in the ocean: The reflectance due to multiple scattering
by air molecules (Rayleigh), reflectance from multiple scattering by atmo-
spheric aerosols, reflectance by interaction between Rayleigh and aerosol
scattering, reflectance emerging from the sea water, the reflectance due to
the Sun glint and the reflectance from white-caps at the air-sea interface.
In this work, only atmospheric processes (molecular and aerosol scattering)
and surface processes (Sunglint) are considered.
