Geoscience Reference
In-Depth Information
This method is based on the effect of variations in the intensity of electromagnetic
field, as well as in the phase and frequency of radiowaves under the transmission of
atmosphere and ionosphere. Eclipse monitoring of the atmosphere and ionosphere
is dependent on the inverse problem being solved so that it can de
ne the vertical
pro
cients and atmospheric tem-
peratures. Subsequent development of this method would involve creation of
algorithms that might make it possible to identify atmospheric and ionospheric
characteristics based on regular measurements.
According to the estimations by many authors the greatest role of microwave
radiometry is displayed under the precipitation and clouds monitoring. For the
les of electron concentrations, refraction coef
rst
time these possibilities were demonstrated by the experiments with satellite
“
in 1968, and then many space microwave measurements were real-
ized by means of SMMR (Scanning Multichannel Microwave Radiometer), SSM/I,
TRMM, and multichannel on-board systems placed on the cosmic station
Cosmos-243
”
“
Mir
”
what
was sunk in 2001.
Local measurements of water vapor concentration in the atmosphere reliable are
registered with wavelength 1.35 cm. Under this the dependence of atmosphere
radiobrightness temperature on the integrated content of water vapor can be well
described by a linear function with a slope equal to
19 K g
−
1
cm
−
1
.
The application of radio waves from the centimeter and millimeter ranges to
diagnose atmospheric properties has been pretty successful because of weak, unlike
the optical and IR ranges, interaction with cloud particles, dust, and atmospheric gas
molecules. Radio wave interaction with rain drops, on the contrary, is resonant and
expressed by the intensive absorption and scattering of wave energy. Therefore,
microwave devices of the active and passive sensing at present time are unique
means giving a possibility to receive from space the data about the precipitation
parameters in global scale.
Microwave observations of precipitation are based on the measurements and
calculations of four Stock; s parameters (Zagorin 1999; Zagorin and Kutuza 1998;
Kutuza et al. 1998, 2000): S ={S
1
, S
2
, S
3
, S
4
), where S
1
is the total intensivity of
radiation, S
2
is the difference between the radiation intensivities of horizontal and
vertical signal polarization, S
3
is the difference of radiation intensivities with linear
orthogonal polarizations respect to the coordinates system turned by 45
≈
, S
4
is the
difference of radiation intensivities of right and left circular polarization. The
Reileigh-Jeans approximation gives S
1
=2k
B
T
j
ʻ
−
2
, where k
B
is the Boltzmann
°
'
s
10
20
mW Hz
−
1
K
−
1
),
constant (=1.38
is the wavelength. These parameters are
the functions of radiobrightness temperatures T
j
of radiation, receiving by the
channels of vertical, T
V
, horizontal, T
h
, under the angle
×
ʻ
, T
±
45
, and circular
(right, Tl)
r
, and left, Tl)
l
) polarizations, and also they are expressed as functions of
complex amplitude for the vertical, E
V
, and horizontal, E
h
, components of electric
±
45
°
field intensity of radiothermal emission (Zagorin abnd Kutuza 1998):
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