Figure 1: Experimental "volumetric 
water content (0-5cm) 
/backscattering coefficient’ 
relationship (5.3 GHz, 
15 .polarization HH ). 
Backscattering coefficient (dB) 
plotted using 0o-6 for the soil water 
content determination (Figure 5). This 
relationship is not any more linear, 
but it can be well modelled by a second 
order polynomial function (0o- 
ó=0.316+0.045oo+0.0012oo 2 ). With the 
set of data used for this analysis, the 
residual standard deviation on the 
moisture determination decreased from 
0.038 m 3 . rrr 3 to 0.035 m 3 . rrr 3 when 
penetration depth is taken into 
account. This small improvement does 
not compensate troubles caused by a 
variable depth for soil sampling. 
Figure 3: Experimental volumetric water- 
content from 0 to 10 cm 
( m 3 /m 3 ) 
volumetric water content 
0.0 0.05 0.15 0.25 0.35 
Figure 2: £>perimental "volumetric 
water content i0- 
5cm )/backscattering 
coefficient" relationship 
(5.3 GHz, 23 .polarization 
VV ). 
Figure 4: "Microwave penetration 
depth/volumetric water 
content" relationship for 
uniform (-) and experimental 
nonuniform (*) water content 
profiles (5.3 GHz, HH 
polarization, 15°) 
Volumetric water content 
(0-penetration depth) 
704