Abstract for IGARSS'98 - 6-10 July 1998, Sheraton Seattle, Seattle, WA  
 
   SURFACE EMISSIVITY AND TEMPERATURE RETRIEVAL 
   FOR A HYPERSPECTRAL SENSOR 
   
  Christoph C. BOREL 
  NIS-2, MS C323 
  Los Alamos National Laboratory 
  Los Alamos, New Mexico 87545, USA 
  Phone: 505-667-8972, FAX: 505-667-8972 
  E-mail: cborel@lanl.gov 

With the growing use of hyperspectral imagers, e.g. AVIRIS in the
visible and short-wave infrared there is hope of using such instruments
in the mid-wave and thermal IR (TIR) some day. We believe that this
will enable us to get around using the present temperature - emissivity
separation algorithms using methods which take advantage of the many channels
available in hyperspectral imagers.

A simple fact used in coming up with a novel algorithm is that a typical
surface emissivity spectrum are rather smooth compared to spectral features
introduced by the atmosphere.
Thus a iterative solution technique can be devised which retrieves
emissivity spectra based on spectral smoothness. To make the emissivities
realistic, atmospheric parameters are varied using approximations, look-up
tables derived from a radiative transfer code and spectral libraries.
One such iterative algorithm solves the radiative transfer equation for the
radiance at the sensor for the unknown emissivity and uses the blackbody
temperature computed in an atmospheric window to get a guess for
the unknown surface temperature. By varying the surface temperature
over a small range a series of emissivity spectra are calculated.
The one with the smoothest characteristic is chosen.
The algorithm was tested on synthetic data using MODTRAN and the Salisbury
emissivity database. 
    
Preferred Topic Area:   Spectrometry
    
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