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