Geoscience Reference
In-Depth Information
eld of
moisted soil and of the soil liquid water content, soil density, temperature and
mineralization level of liquid water are the properties studied both theoretically and
by
Interrelations between the characteristics of the microwave emission
field studies show that microwave
radiometric measurements permit estimates of 7
field measurements. Both research and
10 moisture levels in the top 0.1
-
-
1.0 wavelengths of soil and 3
7 grades of the subsurface water level between 0 and
-
1.5
3.5 m.
The soil moisture is divided into solidly united, loosely united, and free. United
moisture is the water adsorbed by ground particles at the surface and takes the form
of a
-
film of thickness equal to no more than six to eight molecular layers. The
volume of united moisture in the soil layer is determined by the soil type and is
fl
40 % for clay and
loess soils. United water is unattainable by plants and does not in
fluctuated in the wide interval from 2
3 % for sandy soil to 30
-
-
uence the salt
regime of soil. That is why the monitoring system is to realize that kind of moisture
classi
fl
cation in the soil.
The soil moisture is expressed in percent of dry soil weight. Radiation models of
different types of soil moisture that consider soil density, temperature, and salinity
have been studied in great detail. The data required to ascertain moisture levels can
be obtained by means of brightness temperature contrasts, degree of polarization,
and spectral characteristics at centimeter and decimeter wavelengths. Wavelengths
2.25, 18 and 30 cm proved to be the most informative to solve this task. The
microwave radiation model describing the land cover emittively under the condi-
tions of heterogeneously moistened layer is based on the existence of vertical
heterogeneity in the dielectric permeability coef
cient
(see Formula (
2.1
)):
ˁ
s
)
2
. The value of
ʵ ≅
is informative indicator of the moisture soil
variation. As soil moisture begin to grows the
(1 + 0.5
ʵ
first slowly, if soil was
dry, then it increases more rapidly. The weak dependence of
ʵ
increases at
on the initial
moisture stage, explained by moisture tied up in the soil, can be characterized as
having small dielectric permeability. The variety of experimental dependencies of
ʵ
ʵ
from the soil types and moisturizing levels was given by many authors (Shutko
1986; Engman and Chauhan 1995; Borodin and Krapivin 1998; Schmugge 1990;
Tsegaye et al. 2005). Such a knowledge base combined with application of GIMS
technology allows ascertaining water content, W
s
(z), diagnostics in the soil layer.
Basic types of moisture pro
(z),
of dielectric constant were described by Reutov and Shutko (1986). Four major
types of vertical moisture pro
les W
s
(z) of real soils and corresponding pro
les,
ʵ
ed from an analysis of the
moistening characteristics of the various climatic zones in the Former Soviet Union.
In other climatic zones it is necessary to have such identi
les have been identi
cation. As a matter of fact
the task is reduced to the function W
s
(z) reconstruction when the values W
si
= W
s
(z
i
)
are known and the following conditions are satis
ed:
@
W
s
=@
z
j
z¼0
C
;
0
W
s
ðÞ
K
s
ðÞ;
ð
2
:
5
Þ
where K
s
(z) is the given function.
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