Geoscience Reference
In-Depth Information
particles consist of mineral and organic matter. Basic mass of majority soils forms
mineral substances (mineral soils): particles of size more 3 mm form the stony soil
part, particles from 0.01 to 1 mm are called as
“
physical sand
”
, and particles less
0.01 mm are
clay. The minerals that make up the soil consist basically of
two oxides: SiO
2
and Al
2
O
3
. The content of organic substances (mainly humus)
fl
“
physical
”
fluctuates in such soils between 1 and 10 % by the weight. All these circumstances,
when the monitoring system of land covers is designed, lead to the necessity of
microwave channels choice to be informative. The many lengthy investigations in
this
field facilitate choosing the most effective wave range for monitoring many
types of vegetation and soils. Studies of agricultural systems, forest, and arid zones
are inevitable very detailed. Such areas as the control of hydrological soil regime
under the forest canopy and the study of reforestation dynamics in the regions of
clearing and forest
fields to be studied at the nearest
time in the microwave monitoring. This can be done by using the decimeter range
in which the forest canopy is transparent in the microwave range and, consequently,
soil up to the ground waters level can be sensed. Experimental characteristics of the
natural microwave L-band emission of a forest are described by Chukhlantsev and
Shutko (1988), Phillips et al. (2004), and Chukhlantsev (2006).
A possibility of wood-bushes vegetation inventory by means of radiolocation
sensing is based on the correlation between the coef
fires are perspective scienti
c
cients of SHF waves back
scattering and the structure and dielectric properties of vegetation. Using radiolo-
cation systems to control forests is stipulated by the possibilities of additional data
being received together with remote measurements in the visible and IR ranges
(Savin and Bondur 2000).
Global mapping of vegetation in the scale determined by economic needs of
given region is main task of the satellite based radiolocators under the forest
observations. Speci
fires is one of directions in
the development of remote monitoring to assess the vegetation state. Present
satellite- and aviation- based monitoring systems solve many signi
cally, the forest protection from the
cant problems:
•
Operative assessment of the forest
'
s
fire risk;
•
The forest watering mapping under the putting out
fire in the forest;
•
The mapping of the forest
fires contours through the smoke layer and trees
canopy;
•
The determination of the energetic
re parameters;
•
The forest state determination after
re;
Investigations of radiothermal emission from natural layers of a forest that are
combustible such as the lichen, mosses, grass rags, died pine needles, and scrub
have brought about methodologies to identify forest
re parameters based on the
measurements of radiothermal emission in microwave range of electromagnetic
spectrum. The examples of radiobrightness temperature in the forest burning zone
are given in Figs.
2.11
and
2.12
. The leading and rear edges of
re and the burnt
forest in between can clearly be distinguished.
Comparing radiobrightness temperatures registered in different wavelengths
shows that forest
fires emissivity increases with the wavelength decrease and
Search WWH ::
Custom Search