Chapter 15
Analysis of the Reflection Anisotropy. Case
Study: The Numerical Simulation of Waving
Water Surface
Abstract The anisotropic reflection form waved water surface is considered. The
characteristics of the reflected radiation: brightness coefficients and albedo are
calculated. The description of the practice implementation is presented.
15.1 Types of Reflection from Natural Surfaces
Consideration of the optical properties of natural surfaces is the important part of
many problems of the atmospheric optics and radiation transfer theory. It is
especially essential for remote sensing of the atmosphere and surface.
Laws of interaction between radiation and surface is well known (the reflection
angle is equal to the incident angle). However these laws have been formulated for
ideal plane reflected surface. Real surfaces are irregular and (or) rough (grains of sand,
soil clots, vegetation details). Thus the light reflects from every element in accordance
with mentioned laws but the totality of elements (the surface) provides the multitudes
of directions of reflected light (not the single direction as in the ideal case). This
phenomenon is called the diffuse reflection. The reflection in according to the law “the
reflection angle is equal to the incident one” is called here the ideal mirror reflection.
The diffuse reflection might be divided to the set of kinds. The simplest model is
the isotropic reflection, when the reflected radiance is the same for all possible
directions. It is this model that is used in many radiative transfer theory problems
because of its simplicity. Corresponding surface is called isotropic. Only one
parameter – the surface albedo is enough for characterizing the radiation-surface
interaction. The albedo is the ratio of the reflected irradiance to the incident one. It
is evident that the isotropy is the idealization. Fresh snow is the most near to the
isotropic surface. If the reflected radiance is not the same to different directions it is
called the anisotropic reflection and corresponding surface is called the anisotropic
surface. The quasi-isotropic (i.e. the closest to ideal isotropic one, e.g. the fresh
snow), the quasi-mirror (the closest to ideal mirror surface, e.g. the water surface)
and the inversely reflected are possible to set off.
I. Melnikova et al., Remote Sensing of the Environment and Radiation Transfer,
DOI 10.1007/978-3-642-14899-6_15, # Springer-Verlag Berlin Heidelberg 2012
147
Analysis of the Reflection Anisotropy. Case
Study: The Numerical Simulation of Waving
Water Surface
Abstract The anisotropic reflection form waved water surface is considered. The
characteristics of the reflected radiation: brightness coefficients and albedo are
calculated. The description of the practice implementation is presented.
15.1 Types of Reflection from Natural Surfaces
Consideration of the optical properties of natural surfaces is the important part of
many problems of the atmospheric optics and radiation transfer theory. It is
especially essential for remote sensing of the atmosphere and surface.
Laws of interaction between radiation and surface is well known (the reflection
angle is equal to the incident angle). However these laws have been formulated for
ideal plane reflected surface. Real surfaces are irregular and (or) rough (grains of sand,
soil clots, vegetation details). Thus the light reflects from every element in accordance
with mentioned laws but the totality of elements (the surface) provides the multitudes
of directions of reflected light (not the single direction as in the ideal case). This
phenomenon is called the diffuse reflection. The reflection in according to the law “the
reflection angle is equal to the incident one” is called here the ideal mirror reflection.
The diffuse reflection might be divided to the set of kinds. The simplest model is
the isotropic reflection, when the reflected radiance is the same for all possible
directions. It is this model that is used in many radiative transfer theory problems
because of its simplicity. Corresponding surface is called isotropic. Only one
parameter – the surface albedo is enough for characterizing the radiation-surface
interaction. The albedo is the ratio of the reflected irradiance to the incident one. It
is evident that the isotropy is the idealization. Fresh snow is the most near to the
isotropic surface. If the reflected radiance is not the same to different directions it is
called the anisotropic reflection and corresponding surface is called the anisotropic
surface. The quasi-isotropic (i.e. the closest to ideal isotropic one, e.g. the fresh
snow), the quasi-mirror (the closest to ideal mirror surface, e.g. the water surface)
and the inversely reflected are possible to set off.
I. Melnikova et al., Remote Sensing of the Environment and Radiation Transfer,
DOI 10.1007/978-3-642-14899-6_15, # Springer-Verlag Berlin Heidelberg 2012
147