2 Physical Principles and Technical Aspects of Remote Sensing
23
~E 2500
::::1.
i 2000
~
c
.~ 1500
"0
~ ....
~ 1000
t5 (])
0.
U)
500
0.5
1.0
1.5
2.0
2.5
3.0
Wavelength [11m]
Fig. 2.6. Solar irradiance outside the atmosphere (upper curve) and after passing
vertically through a standard atmosphere (lower curve)
'tatm
Atmosphere
Surface
Target (r,>
Fig. 2.7. Contributions to satellite-observed radiance of reflected solar radiation.
The radiation fluxes are explained in the text
various types of reflectance functions (Vermote et al., 1997). If no information
on atmospheric properties is available, empirical atmospheric corrections can
be applied, relying on targets with known and temporally stable reflectivity
(Schott, 1997).