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The approach to the selection of the optimum wave
length range is as follows. Since the large variance of
the radio-brightness temperatures of the boggy areas is
caused by the non-uniform wetting, then at the selected
wavelength the vegetation layer should be transparent or
semi-transparent in order to screen the soil and the water
areas of small size. At the same time the terrain resolu
tion should be not much more than the characteristic size
of nonuniformities £ . The terrain resolution D depends on
parameters of the antenna and wavelength. Thus, relation
ships (3) should be supplemented with the restraint of the
type I>(A,d) « K a P
(6)
where d - is the vector of antenna parameters;
Kci-is the constant determined by the three-dimen
sional spectrum of electrophysical heterogeneity
of the object causing fluctuations of radio
brightness temperatures.
Just as in the earlier case selection of polariza
tion has become biased in favour of the horizontal one not
only because of the less absorption in the vegetation
layer but also because of large differences in the radio
brightness temperatures under the same variation of elect
rophysical parameters.
In our opinion, the joint use of the microwave radio-
metrical and multizonal measurements are highly promising
in studying forests. One of such problems here is the
assessment of fire-hazardness of forests.
From the results of the joint processing of the aerial
photos and synchronous microwave radiometrical measurements
we have developed the technique for assessing fire hazard-
ness of forests. The appropriate ground measurements were
conducted synchronously which included determination of
the level of ground water, detailed forest-estimation
description of the route being investigated and assessment
of fire hazardness with the use of standard methods. The
algorithm developed on the basis of the obtained informa
tion makes it possible to estimate the fire-hazardness
