Figure 9 shows the inverted reflectance spectra for the polo field in comparison with a reflectance spectrum 
measured at the polo field The agreement provides preliminary validation tliat the effects of the solar 
irradiance spectrum, the aerosol scattering, the well mixed gas absorption and scattering, the water vapor 
absorption have been compensated. Figure 10 shows the inverted apparent reflectance spectrum for the golf 
course showing the expected vegetation absorption and cellular scattering spectrum. 
Figure 10 : An AVIRIS inverted reflectance spectrum for the golf course 
6 - CONCLUSION 
Radiative transfer code based NLLSSF algorithms are described that allow direct estimation of parameters 
constraining the absorption and scattering characteristics of the atmosphere. These parameters arc derived 
directly from the imaging spectrometer measured spectral upwelling radiance. These NLLSSF algorithms were 
applied to each spatial element of the AVIRIS data acquired over Jasper Ridge, California, in 1992. The 
derived atmospheric parameters and illumination geometry were used to constraint the MODTRAN radiative 
transfer code to invert the AVIRIS measured spectral radiance to apparent surface reflectance for each spatial 
element A preliminary validation is given through comparison of the inverted apparent reflectance and the in 
situ measured reflectance for a target in the data set. In inversion of imaging spectrometer radiance to apparent 
surface reflectance. Surface reflectance is used to investigate molecular absorption and particle scattering 
characteristics of constituents in the disciplines of ecology, geology, oceanography and snow hydrology. 
Acknowledgments 
This research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under 
contract with the National Aeronautics and Space Administration.