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30/06/2007 |
The emissivity Spatial, Spectral and Angular Variations The land AMSU emissivities have been
analysed and their angular and their frequency dependencies examined. The emissivity varies smoothly in
frequency (at least for snow free areas). This makes it possible
to extrapolate, at a specific location, the emissivity at sounding
frequencies from the window
channel estimates. The temporal and spatial variations of AMSU
emissivities have also been studied. In addition,
good agreement has been found between AMSU, SSM/I, AMSR-E
and TMI emissivities. AMSU emissivities varies with the frequency, with the
surface type and also with the observation scan angle.
For instance, there is a strong angular dependence of the AMSU
emissivity over bare soils whereas
it is negligible over forested land. Additional resulats are presented
in Karbou et al. 2005.
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