M.Sc Thesis

M.Sc StudentOved Amit
SubjectWeak Coupling of Spectral-Dimensional Scattering Functions
for Atmospheric Recovery and Correction
DepartmentDepartment of Physics
Supervisors PROFESSOR EMERITUS Stephen Lipson
PROF. Yoav Schechner
Full Thesis textFull thesis text - English Version


Radiation from the Earth’s surface undergoes significant spectral modification due to interaction with the atmosphere, before reaching a measuring device located at high altitude. Estimating the effect of the atmosphere on measurements of the Earth is crucial for a variety of remote-sensing tasks, atmospheric sciences, pollution monitoring and radiation budget estimation. During recent years, several approaches have been proposed for estimation of the atmospheric optical characteristics. Usually, each approach is tailored to a specific measuring device and scene.

In this work, we present a parametric model for the interaction of radiation with the earth's surface and atmosphere. The data we use is composed of multi-directional and multi-spectral measurements of Earth, taken by a space-borne measuring device called Multi-angle Imaging SpectroRadiometer ('MISR'). MISR measures radiance at the top of the atmosphere in four spectral bands and at nine angles. The estimation of the surface and atmospheric radiative properties is done by finding a set of parameters which minimize the difference between the model and the real data.

At the heart of the model lies a property which we assume many natural surfaces possess. The property is separability of the spectral and directional parts of the surface Bidirectional Reflectance Distribution Function. It is possessed (to some extent) by any surface which does not change its apparent hue when viewed from different directions. This assumption poses strong constraints on the directional distribution of the surface-leaving radiance, at different wavelengths. Exploiting the relative transparency of the atmosphere in the near-infrared band, allows direct measurement of the surface-leaving radiance at this band. Using the low-dimensionality dependence property and near-infrared measurements, surface-leaving radiance at all other measured bands is known up to a few (unknown) parameters. In addition, exponential attenuation of surface-leaving radiation and path radiance are also inserted into the model. By minimizing the difference between the model and real data, the optimal parameters can be found. Having these parameters enables the reconstruction of the surface-leaving radiance and quantification of some atmospheric properties.