118 
Backscattering coefficient (dB) Backscatterlng coefficient (dB) 
Figure 4 : 
15 
10 
5 - 
0 - 
-5 L. 
1.1 
0 
-5 - 
■10 - 
■15 - 
-20 L 
1.1 
The backscattering coefficient as 
a function of the Tortuosity index 
for two angles of incidence (5.3 
Hz, Polarization HH) 
s 
Angle of incidence 0’ 
s* 
s, 
9 
So 
1.2 1.3 1.4 1.5 1.« 1.7 1.8 
Tortuosity Index 
Angle of incidence 50* 
s; 
i 
S 1 
o 
So 
_i 1 1 « 1 1——i 
1.2 1.3 1.4 1.5 1.8 1.7 1.8 
Tortuosity index 
— Dry 
* Dry (only one measurement) 
- Wet 
0 Wet (only one measurement) 
Figure 5: Relationships between the 
reflectance in SPOT bands and the 
Tortuosity index (T) under wet 
and dry soil moisture conditions 
(0‘ angle of incidence, midday) 
Figure 6 : The effect of the solar illumination 
angle on the spectral behavior of 
bare soil during slaking (Dry soil 
moisture condition, 0* angle of 
incidence) 
a XS1 
□ XS2 
. XS3