Information about the Earth and its environment is collected on a continuoual
basis from
an array of instruments either already in space or to be deployed on
Earth-orbiting satellites. Similar information is also collected from
air-borne platforms. Most of
the instruments deployed on aircraft or on Earth-orbiting satellites measure
electromagnetic radiation at a multitude of wavelengths between the ultraviolet
and the microwave region of the spectrum.
In passive remote sensing the measured signal is due either to solar radiation
reflected by the Earth-atmosphere system or else emitted by the Earth's surface
and the
atmosphere. Proper interpretation of the measured signal require knowledge of
the
interaction of the radiation with the atmosphere and the underlying surface.
Thus, in the remote sensing community there is a need to know how the radiance
at the
top-of-the-atmosphere (TOA) or at aircraft altitude depends on atmospheric and
surface parameters.
The most important of these parameters are the aerosol optical depth and the
surface reflectance (albedo or Bidirectional Reflectance Distribution Function,
BRDF). The TOA radiance is exactly what an instrument deployed on an
Earth-orbiting satellite would measure. Thus, a computational tool that predicts
how the TOA radiance depends on aerosol optical depth and surface reflectance is of
great interest to the remote sensing community.
Design and construction of algorithms for accurate 'atmospheric correction' play
a crucial role in remote sensing of surface characteristics. Such corrections are
necessary to enable the user to retrieve the radiance emanating from lakes and
marine bodies of water, and the radiance leaving a plant canopy on land. The radiance
leaving the plant canopy or the water contains the information needed to
assess biological
productivity on land or in the water.
We are currently developing research tools that can be used to extract
information about the environment from in situ and remote sensing data.
These tools will enable
the user to obtain information about the Earth-atmosphere system by properly
analyzing the remotely-sensed data.