Method for radar measurement of cloud and precipitation particle charge

FIELD: radio engineering, communication.

SUBSTANCE: in the disclosed method, the region of the atmosphere under investigation is simultaneously irradiated with an electromagnetic wave with wavelength λ₁, which is not damped during propagation in the investigated medium, and a wave with length λ₂, which is damped; reflected electromagnetic signals from two volumes lying within the investigated region are received; power of the electromagnetic signals reflected from the first and second volumes, as well as phase shift between said signals are measured separately and the measurement results are used to determine the cloud and precipitation particle charge of the investigated region using the formula:

$$\rho =K\cdot \frac{1}{{\lambda }_2\cdot (R_2-R_1)}\cdot \frac{lg(\raisebox{1ex}{$u_{pd}$}\!\left/ \!\raisebox{-1ex}{$U_0$}\right.)}{lg\left[cos(\frac{2\pi \text{}(R_2-R_1)}{{\lambda }_2})\right]}\cdot \Delta ,\left(1\right)$$

where $$K=\frac{m\cdot c}{60\cdot e}=2,84\cdot 10^{-5}\frac{Cl}{m}$$ is a constant; m is electron mass; e is electron charge; c is the propagation speed of the electromagnetic wave; R₁ and R₂ denote distance to the two volumes lying within the investigated region; U_pd is the complex voltage at the output of the phase detector; U₀ is the amplitude of voltage at the output of the amplitude limiter; $$\Delta =\left[ln{(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_1}-ln{(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_2}\right]$$ is the difference of logarithms of the ratio of the power values of the reflected radar signal from two regions of the investigated space lying at distance R₁ and R₂ from the radar, respectively; P(λ₁) is the power of the reflected signal with length of the undamped wave of λ₁; P(λ₂) is the power of the reflected signal with wavelength of λ₂, which is damped in the investigated volume of the cloud or precipitation.

EFFECT: longer range and reduced dependency of charge measurement results on the state of the atmosphere.

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The invention relates to meteorology, in particular, to remote methods of measurement of characteristics of the atmosphere and can be used in automated systems definition of hazardous aviation weather events, as well as in other areas of human activity where knowledge is required about the amount of charge of the particles, clouds, and precipitation.

By the way - analog is the way to determine the charge clouds, along with the charge of the aircraft, which is estimated from measurements of the average radar reflectivity of clouds [1. Hasina D.B Communication radar characteristics of clouds with their turbulent and electrical condition. Tr. MGO, 1965, VIP, p.58-62].

The disadvantage of this method is unacceptably large error in determining the amount of charge of the aircraft (average charge clouds) on average radar reflectivity.

The closest in technical essence and the achieved result of the claimed method of measuring the charge of the particle clouds and precipitation (the prototype of the present invention) is a method radiocasting measurement of the charge of the aerosol particles in the atmosphere [2. RF patent №2319981. Priority from 20.11.06, bull. No. 8, 2008], which is the energy of the acoustic wave in the investigated volume of the atmosphere containing charged particles, definition wide-angle and the charge of the aerosol particle characterization initiated by electromagnetic signal - the strength of the electric field. In the method-prototype information about the charges of the particles get in the spectrum of acoustic frequencies, which leads to a restriction of range and significant dependence of the accuracy of determination of the charge particles from the atmosphere.

The technical result of the invention is to increase the range and reduce the dependence of the measurement results of charge from the state of the atmosphere.

The technical result is achieved by the fact that the analyzed region of the atmosphere simultaneously irradiate an electromagnetic wave with wavelength λ₁, continuous with the distribution in the studied environment, and wave with λ₂experiencing attenuation; takes the reflected electromagnetic signals from the two volumes that lie within the study area, measured separately power of the electromagnetic signal reflected from the first and second volumes, as well as the magnitude of the phase shift between these signals and the results of measurements to determine particle charge clouds and precipitation in the study area according to the formula:

$$\rho =K\cdot \frac{1}{{\lambda }_2\cdot (R_2-R_1)}\cdot \frac{lg(\raisebox{1ex}{$u_{F\mathrm{D/mi>}}$}\!\left/ \!\raisebox{-1ex}{$U_0$}\right.)}{lg\left[cos(\frac{2\pi (R_2-R_1)}{{\lambda }_2})\right]}\cdot \Delta ,\left(1\right)$$

where$$K=\frac{m\cdot c}{60\cdot e}=2,84\cdot 10^{-5}\frac{Kl}{m}$$ - constant coefficient; m is the electron mass; e is the electron charge; C is the speed of propagation of electromagnetic waves; R₁and R₂- distance to the two volumes that lie within the study area; U_FD- integrated value of the voltage at the output of the phase detector; U₀- peak value of the voltage at the output of the amplitude limiter;$$\Delta =\left[ln{(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_1}-ln{(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_2}\right]$$the difference between the logarithms of the relationship of the capacity of the reflected radar signal from two areas of study space, remote from the radar at a distance of R₁and R₂respectively; R(λ₁- the power of the reflected signal with the length of the continuous wave λ₁; P(λ₂- the power of the reflected signal with wavelength λ₂experience what she attenuation in the volume under study clouds or precipitation.

The essence of the proposed method lies in the fact that for more information about the charge of the aerosol particles, clouds and precipitation is used is known from Maxwell theory the dependence of the absorption of electromagnetic waves of the investigated volume cloudy atmosphere from the electrophysical properties of aerosol particles in this volume [3. Shifrin, K.S. light Scattering in turbid environment. - M.: State. Izdat., 1951. - Ñ.38-43, 50-52; 4. Dolukhanov BTW, the Propagation of radio waves. - M.: Owls. Radio, 1960. - P.24-27], on the one hand, and dependence of electrophysical properties of aerosol particles from their charges [4. Dolukhanov BTW, the Propagation of radio waves. - M.: Owls. Radio, 1960. - S-243; 5. S. Dukhin conductivity and electrokinetic properties of dispersed systems. - Kyiv: Publishing house "Naukova Dumka", 1975. - S-108] - on the other side.

In this regard, emit a radar signal simultaneously at two wavelengths λ₁and λ₂in the direction of the investigated volume of clouds or precipitation of the charged aerosol particles. For two regions of space that lie within the survey area along the beam of radar and remote from him on the R₁and R₂to measure reflected aerosol particles of electromagnetic signals. For information about the signal power and phase shift between them receive information about the electrophysical characteristics of aerosols the x particles, which in turn is related to the magnitude of the charge of the particles.

The way radar measurements of particle charge clouds and precipitation is illustrated by the figure, which shows: meteorological radar (MRLS), consisting of the transmitting devices 1 and 2, a dual-band antenna 3, the receiver of the electromagnetic wave length λ₁4, the receiver of the electromagnetic wave with wavelength λ₂5, divider capacity output signals 6 from the receivers 4 and 5, calculate the logarithm 7, device delay signal 8, the amplitude limiter 9, phase detector 10, a casting device 11 connected as shown in the figure; and the measurement object 12.

Transmitting devices MRLS 1 and 2 simultaneously create the probing pulses of microwave oscillations of a large capacity with wavelengths λ₁and λ₂that radiate dual band antenna 3. Reflected from object 12 of the probe pulses are accepted dual-band antenna 3 and fed to the receivers 4 and 5. Electromagnetic signal, do not have absorption in the studied environment - in receiver 4; experiencing absorption in the receiver 5. Next, the signals are directly and through the delay device 8 by the divider 6, which is the division of power of signals received from the output of the receivers 4 and 5. From the output of the divider 6 signals transported the t logarithmorum device 7, after serving on the crucial device 11. Simultaneously, the signal from the receiver 5, experiencing absorption in the studied environment is directly and through the delay device 8 on the amplitude limiter 9, the output of which the voltage amplitude threshold U₀enters the phase detector 10. From the output of the phase detector 10 and the amplitude limiter 9 voltage signals are at a critical device 11, which is determined by the value of the charge particles in accordance with formula 1.

The way radar measurements of particle charge clouds and precipitation explained as follows.

For information about the charges of aerosol particles it is necessary to determine the parameters characterizing the electrical properties of the investigated aerosol particles. Since the average distance between particles is much less than the wavelengths emitted MRLS, the analyzed volumes clouds can be regarded as a continuous medium, electrophysical properties of which are determined by the electrical and physical properties of aerosol particles, namely, the absorption coefficient (p) and refractive index (n) [3. Shifrin, K.S. light Scattering in turbid environment. - M.: State. Izdat., 1951. - S]. To investigate the possibility of determining these coefficients consider the values of electric field intensity of radio waves, reflected the volume of the investigated area, containing aerosol particles [6. Stepanenko E Radar in meteorology. - L.: Gidrometeoizdat, 1966. - P.9-13; 4. Dolukhanov BTW, the Propagation of radio waves. - M.: Owls. Radio, 1960. - S].

For waves that do not undergo absorption and reflected from volumes disposed in the R₁and R₂we obtain

$$\stackrel{}{E}\left(R_2,{\lambda }_1\right)=\frac{1}{R_2^2}\sqrt{{\sigma }_{21}}{E}_m\left(R_2\right)e^{j\omega \left(t-\frac{R_2}{c}n\right)}.\left(3\right)$$

For waves, affected the absorption and reflected from volumes disposed in the R₁and R₂

_{$$\stackrel{}{E}\left(R_1,{\lambda }_2\right)=\frac{1}{R_1^2}\sqrt{{\sigma }_{12}}{E}_m\left(R_1\right)e^{-\frac{4\pi }{{\lambda }_2}p{R}_1}{e}^{j{\omega }_2\left(t-\frac{R_1}{c}n\right)},\left(4\right)$$}

_{$$\stackrel{}{E}\left(R_2,{\lambda }_2\right)=\frac{1}{R_2^2}\sqrt{{\sigma }_{22}}{E}_m\left(R_2\right)e^{-\frac{4\pi }{{\lambda }_2}p{R}_2}{e}^{j{\omega }_2\left(t-\frac{R_2}{c}n\right)},\left(5\right)$$}

_{where σijeffective reflective surface of the i-th volume of the investigated area for the j-th wavelength, p is the absorption coefficient of the electromagnetic wave;and$${\omega }_2=\frac{2\pi \cdot c}{{\lambda }_2}$$circular frequency is; c is the velocity of propagation of electromagnetic waves.}

The signal power at the input of the receiver of the radar in both wavelength ranges will be determined by the formula [6. Stepanenko E Radar in meteorology. - L.: Gidrometeoizdat, 1966. - S]

$$P_{R1}\left({\lambda }_1\right)=\frac{C_1\cdot {\sigma }_{11}\left({\lambda }_1\right)}{R_1^2},P_{R2}\left({\lambda }_1\right)=\frac{C_1\cdot {\sigma }_{21}\left({\lambda }_1\right)}{R_2^2}\left(6\right)$$

$$P_{R1}\left({\lambda }_2\right)=\frac{C_2\cdot {\sigma }_{12}\left({\lambda }_2\right)}{R_1^2}{e}^{-\frac{4\pi }{{\lambda }_2}{\displaystyle \underset{0}{\overset{R1}{\int }}pdR}},P_{R2}\left({\lambda }_2\right)=\frac{C_2\cdot {\sigma }_{22}\left({\lambda }_2\right)}{R_2^2}{e}^{-\frac{4\pi }{{\lambda }_2}{\displaystyle \underset{0}{\overset{R2}{\int }}pdR}}\left(7\right)$$

where C₁C₂are constants.

For two regions of space that lie within the survey area, the distance to which R₁and R₂the logarithm of the relations of power signals at two wavelengths equal to

$$ln{(\frac{P\left({\lambda }_1\right)}{P({\lambda }_2)})}_{R_1}=ln\frac{C_1}{C_2}+ln{(\frac{{\sigma }_{11}({\lambda }_1)}{{\sigma }_{12}({\lambda }_2)})}_{R_1}-\frac{4\pi }{{\lambda }_2}{\displaystyle \underset{0}{\overset{R_1}{\int }}pdR,\left(8\right)}$$

$$ln{(\frac{P\left({\lambda }_1\right)}{P({\lambda }_2)})}_{R_2}=ln\frac{C_1}{C_2}+ln{(\frac{{\sigma }_{21}({\lambda }_1)}{{}_{22}({\lambda }_2)})}_{R_2}-\frac{4\pi }{{\lambda }_2}{\displaystyle \underset{0}{\overset{R_2}{\int }}pdR}.\begin{array}{ccc}& & \end{array}\left(9\right)$$

The difference of the logarithms of relations capacity

$$\Delta =ln\frac{{\left(\frac{{\sigma }_{11}\left({\lambda }_1\right)}{{\sigma }_{12}\left({\lambda }_2\right)}\right)}_{R_1}}{{\left(\frac{{\sigma }_{21}\left({\lambda }_1\right)}{{\sigma }_{22}\left({\lambda }_2\right)}\right)}_{R_2}}+\frac{4\pi }{{\lambda }_2}{\displaystyle \underset{R_1}{\overset{R_2}{\int }}mi>\; pdR.}\begin{array}{ccc}& & \end{array}\left(10\right)$$

Because the range of droplet size does not change during the sensing within the studied area [6. Stepanenko E Radar in meteorology. - L.: Gidrometeoizdat, 1966. - S-271], the first term in the right-hand side of equation (10) equals zero, then

$$\Delta =\frac{4\pi }{{\lambda }_2}{\displaystyle \underset{R_2}{\overset{R_1}{\int }}pdR}\text{or}$$$$p=\frac{{\lambda }_2}{4\pi }\frac{\Delta }{R_2-R_1}=\frac{{\lambda }_2}{4\pi }\cdot \frac{ln{(\frac{P\left({\lambda }_1\right)}{P({\lambda }_2)})}_{R_1}-ln{(\frac{P\left({\lambda }_{}\right)}{P({\lambda }_2)})}_{R_2}}{R_2-R_1},\left(11\right)$$

where p is the average value on the interval (R₁, R₂), (measured by the difference of the logarithms of the capacity of the radar signal at two wavelengths λ₁and λ₂.

To determine the refractive index serves voltage created the reflected signals with wavelength λ₂two volumes of$$\stackrel{}{u}\left(R_1,{\lambda }_2\right)$$and$$\stackrel{}{u}\left(R_2,{\lambda }_2\right)$$, amplifiers, limiters, to exclude the influence of the value of these voltages on the output voltage of the phase dete the Torah

$$\stackrel{}{u}\left(R_1,{\lambda }_2\right)={\stackrel{}{U}}_{10}{e}^{j\omega t},\left(12\right)$$

By submitting this voltage to the input of the phase detector, its output will receive:

$${\stackrel{}{u}}_{FD}=U_0{e}^{-j\omega \frac{R2-R1}{c}n},\text{<mrow> <mo> ( </mo> <mrow> <mn> 1 </mn> <mn> 4 </mn> </mrow> <mo> ) </mo> </mrow>}$$

where U₀- peak value of the voltage at the output of the amplitude limiter;$${\stackrel{}{u}}_{FD}$$- integrated value of the voltage at the output of the phase detector. Taking the real part of the expression (14), get:

$$u_{FD}=U_0\cdot cos(2\pi \frac{R_2-R_1}{{\lambda }_2}n).\left(15\right)$$

Using the de Moivre formula [7. The Dwight G.B. Tables of integrals and other mathematical formulas. - M.: "Nauka", 1964. - P.76] and after conversion the of get

$$n=\frac{lg(\raisebox{1ex}{$u_{FD}$}\!\left/ \!\raisebox{-1ex}{$U_0$}\right.)}{lg\left[cos(\frac{2\pi (R_2-R_1)}{\lambda })\right]}.\left(16\right)$$

To determine the charge of the aerosol particles contained in the volume under study, we need to find is elicina conductivity γ _CRthat is associated with the refractive index n and absorption of p the following relations [4. Dolukhanov BTW, the Propagation of radio waves. - M.: Owls. Radio, 1960. - P.27; 8. Jaworski BM, Detlef A.A. physics Handbook. - M.: "Nauka", 1990. - S-217]

$$2np=60\lambda {\gamma }_{np}.\left(17\right)$$

Then charge the investigated volume is equal to

$$j_{np}=E{\gamma }_{np}=\rho \cdot V,\rho =\frac{{\gamma }_{np}}{V}E\left(18\right)$$

where p is the charge of the investigated volume, V is the velocity of the charge, j_npis the density of conduction current.

Since in the investigated volume of the charged aerosol particles are carriers of free elementary charges - electrons, in an alternating electric field, they will move with velocity V according to the following law [4. Dolukhanov BTW, the Propagation of radio waves. - M.: Owls. Radio, 1960. - S-243]

$$e{E}_m\cdot e^{iwt}=m\frac{dV}{dt}+\beta m\cdot V,\left(19\right)$$

where m and e are mass and charge of the electron; β - coefficient of the collision of electrons.

The solution of equation (19) represents a

$$V=\frac{e\cdot \beta \cdot E}{m\left(w^2+{\beta }^2\right)}-i\frac{e\cdot w\cdot E}{m\left(w^2+{\beta }^2\right)}.\text{the}\left(20\right)$$

Then taking into account (17) and (18), have

$$\rho =\frac{{\gamma }_{np}\cdot E}{\left[\frac{e\cdot \beta \cdot E}{m\left(w^2+{\beta }^2\right)}-i\frac{e\cdot w\cdot E}{m\left(w^2+{\beta }^2\right)}\right]}\text{what is}\left(21\right)$$

The value of the coefficient of collisions of the charge carriers - electrons is significantly less than the frequency of the electromagnetic wave radar signal β≈10⁵<<ω≈10¹⁰Hz [4. Dolukhanov BTW, the Propagation of radio waves. - M.: Owls. Radio, 1960. - S-316], therefore, the formula (21) can be rewritten in the form

$$\rho =i\frac{{\gamma }_{np}\cdot m\cdot \omega }{e},\left(22\right)$$

Then by analogy with [9. Bohren C.F., A.J. Hunt Scattering of electromagnetic waves by a charged sphere // Can. J. Phys. - Vol.55. - 1977. - P.1930-1935.], the charge of the studied environment will be determined by the coefficient of the imaginary part of equation (22).

Thus, taking into account(11), (16), (17) and (22), the value of the charge study space will be determined by the formula

$$\rho =K\cdot \frac{1}{\lambda \cdot (R_2-R_1)}\cdot \frac{lg(\raisebox{1ex}{$u_{FD}$}\!\left/ \!\raisebox{-1ex}{$U_0$}\right.)}{lg\left[cos(\frac{2\pi (R_2-R_1)}{\lambda })\right]}\cdot \Delta ,\left(23\right)$$

where$$K=\frac{m\cdot c}{60\cdot e}=2,84\cdot 10^{-5}\frac{Kl}{m}$$- constant coefficient;

$$\Delta =\left[\ln {(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_1}-\ln {(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_2}\right]$$the difference between the relationship of the logarithm of the capacity of radar signals.

Consider the example of a specific implementation of the present with the person and obtain a technical result.

Typical radar simultaneously emits electromagnetic waves with a length of 3.2 cm and 10 cm this registers the response of an electromagnetic wave from the areas studied in the cloud space, remote, for example, R₁=40 km and R₂=50 km is Determined by the difference of the logarithms of the relationship of the capacity of the electromagnetic signal, for example Δ=1,8·10^-3and the ratio of the voltages at the outputs of the amplitude limiter and phase detector, for example, u_FD/U₀=0,88. The calculation of the charge investigated cloud space is calculated by the formula

$$\begin{array}{l}\rho =K\cdot \frac{1}{\lambda \cdot (R_2-R_1)}\cdot \frac{lg(\raisebox{1ex}{$u_{FD}$}\!\left/ \!\raisebox{-1ex}{$U_0$}\right.)}{lg\left[cos(\frac{2\pi (R_2-R_1)}{\lambda })\right]}\cdot \Delta =2,84\cdot 10^{-5}\cdot \frac{1}{0,032\left(50000-40000\right)}\cdot \\ \cdot \frac{lg\left(0,88\right)}{lg\left[cos(\frac{2\pi \cdot 10000}{0,032})\right]}\cdot 1,8\cdot 10^{-3}=2,84\cdot 10^{-9}\cdot \frac{1}{0,032}\cdot 1,08\cdot 1,8\cdot 10^{-3}\approx 1,7\cdot 10^{-10}\frac{Kl}{m^3}\end{array}$$

Thus, calculations were performed using the averaged data of long-term observations of meteorological and physical parameters in the atmosphere showed the efficiency of the proposed method.

The results obtained indicate the existence of a causal link between the new set of essential priznakov proposed method and achievable technical result.

The proposed solution is industrially applicable, so as to implement templates can be used for radio hosts and devices used in MRLS, as well as equipment and materials in the microwave range, is a widespread technology.

The way radar measurements of particle charge clouds and precipitation, which in the energy impact on the analyzed volume, measuring electromagnetic response signal and determining the amount of charge on the characteristics of the electromagnetic response signal, wherein the analyzed region of the atmosphere simultaneously irradiate an electromagnetic wave with wavelength λ₁, continuous redistributions of clouds and precipitation, and wave with λ₂experiencing attenuation; takes the reflected electromagnetic signals from the two volumes that lie within the study area, measured separately power of the electromagnetic signal reflected from the first and second volumes, as well as the magnitude of the phase shift between these signals, and the measurement results determine the charge of the particle cloud and precipitation of the study area according to the formula:
$$\rho =K\cdot \frac{1}{{\lambda }_2\cdot (R_2-R_1)}\cdot \frac{lg(\raisebox{1ex}{$U_{FD}$}\!\left/ \!\raisebox{-1ex}{$U_0$}\right.)}{lg\left[cos(\frac{2\pi (R_2-R_1)}{{\lambda }_2})\right]}\cdot \Delta ,\left(1\right)$$
where$$K=\frac{m\cdot c}{60\cdot e}=2,84\cdot 10^{-5}\frac{Kl}{m}$$- constant coefficient; m is the electron mass; e is the electron charge; C is the speed of propagation of electromagn is based wave; R₁and R₂- distance of two volumes that lie within the study area; U_FD- integrated value of the voltage at the output of the phase detector; U₀- peak value of the voltage at the output of the amplitude detector;
$$\Delta =\left[ln{(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_1}-ln{(\frac{P({\lambda }_1)}{P({\lambda }_2)})}_{R_2}\right]$$the difference between the logarithms of the relationship of the capacity of the reflected radar signal from two areas of study space, remote from the radar at a distance of R₁and R₂respectively; P(λ₁- the power of the reflected signal with the length of the continuous wave λ₁; P(λ₂- the power of the reflected signal with wavelength λ₂experiencing attenuation in the volume under study clouds or precipitation.