Method for multi-position determination of optical atmospheric characteristics

FIELD: physics.

SUBSTANCE: short light pulses are emitted into an inhomogeneous atmosphere and echo signals are received. The echo signals are corrected for the lidar geometric factor. The corrected signals are accumulated during a given period of time depending on the overall length of the investigated area. The light pulses are deflected in at least two points of the probing path in directions towards a common scattering volume. Optical thickness of the area enclosed between points where the pulses are deflected is taken into account in order to determine transparency of the atmosphere.

EFFECT: high accuracy of determination due to correct accounting for influencing factors.

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The invention relates to the field of meteorology, and more specifically to methods for characterization of atmospheric pollution, and can be used, for example, for measuring the transparency of the atmosphere lidar systems when determining the aerosol pollution of the air.

There is a method of optical sensing of inhomogeneous atmosphere [1], which are making the atmosphere light pulses on crossing paths sensing, passing through noncollinear directions, carry out the reception of the echo signals, and the characteristics of the atmosphere is determined by the capacity of the echo signals using the calculated formulas.

This known method has low accuracy, because it is based on the assumption about the possibility of differentiation of the echo signals. This assumption is not performed in real inhomogeneous atmosphere.

Closest to the proposed invention is a method of optical sensing of inhomogeneous atmosphere [2], in which the parcel in an inhomogeneous atmosphere light pulses of short duration and receiving echo signals; provides correction of the echo signals on the geometric factor lidar; accumulate the adjusted signals within a specified period of time depending on the total length of the study involved the ka.

In this known solution improves the accuracy of the characterization of heterogeneous contamination of the atmosphere due to the fact that the echo signals accumulate within a specified period of time depending on the total length of the investigated area. However, the solution [2] is based on the assumption of the constancy of the relationship of the coefficient of the inverse scattering to the attenuation coefficient on the studied highway sensing. This assumption is not performed in real inhomogeneous atmosphere.

The technical result of the invention is to improve the accuracy of determining the characteristics of the atmosphere due to the correct accounting due coefficient backscattering and attenuation coefficient.

In the proposed method uses some of the essential features of the prototype, namely: there are package in a nonuniform atmosphere of light pulses of short duration and receiving echo signals; provides correction of the echo signals on the geometric factor lidar; accumulate the adjusted signals within a specified period of time depending on the total length of the investigated area.

Salient features of the proposed method is that the light pulses reject no less than two points of sounding in the directions on a common race is living volume, and to determine the transparency of the atmosphere into account the optical thickness of the area enclosed between the points at which rejects pulses.

The optical characteristics of heterogeneous contamination of the atmosphere, in particular optical thickness

$$t_1={\displaystyle \underset{R_1}{\overset{R_1+{\Delta }_1}{\int }}\sigma dR,\left(1\right)}$$

$$t_2={\displaystyle \underset{R_1}{\overset{R_2+{\Delta }_2}{\int }}\sigma dR\left(2\right)}$$

where σ is the attenuation coefficient,

R_idistance from the lidar to the point of deviation pulse

Δ_i- the distance from the point of deviation of the pulse to the scattering volume,

found from the system of equations:

$$\frac{\sqrt[g]{S_1\left(R_1\right)}}{{\sigma }_1}-\frac{\sqrt[g]{S_1\left(R_1+{\Delta }_1\right)}}{\sigma }=\frac{2}{g}{\displaystyle \underset{R_1}{\overset{R_1+{\Delta }_1}{\int }}\sqrt[g]{S_1}dR\left(3\right)}$$

$$\frac{\sqrt[g]{S_2\left(R_1\right)}}{{\sigma }_1}-\frac{\sqrt[g]{S_2\left(R_2+{\Delta }_2\right)}}{\sigma }=\frac{2}{g}{\displaystyle \underset{R_1}{\overset{R_2+{\Delta }_2}{\int }}\sqrt[g]{S_2}dR\left(4\right)}$$

$$\frac{\sqrt[g]{S_2\left(R_2\right)}}{{\sigma }_2}-\frac{\sqrt[g]{S_2\left(R_2+{\Delta }_2\right)}}{\sigma }=\frac{2}{g}{\displaystyle \underset{R_2}{\overset{R_2+{\Delta }_2}{\int }}\sqrt[g]{S_2}dR\left(5\right)}$$

$$\sqrt[g]{\frac{S_2\left(R_1\right)}{S_2\left(R_2\right)}}=\frac{{\sigma }_1}{{\sigma }_2}\exp \left(\frac{2}{g}{\displaystyle \underset{R_1}{\overset{R_2}{\int }}\sigma dR}\right)\left(6\right)$$

$$\sqrt[g]{S_1\left(R_1\right)S_1\left(R_1+{\Delta }_1\right)}=\frac{{\sigma }_1}{{\sigma }_{}}\exp \left(\frac{2}{g}{t}_1\right)\left(7\right)$$

$$\sqrt[g]{\frac{S_2\left(R_2\right)}{S_2\left(R_2+{\Delta }_2\right)}}=\frac{{\sigma }_1}{{\sigma }_{}}\exp \left(\frac{2}{g}{t}_2\right)\left(8\right)$$

where S is the signal power of the backscattered adjusted geometric factor from lidar.

When this is determined, and the constant g in a power-law relation of the coefficient of the inverse scattering attenuation coefficient

\beta =D{\sigma }^g.\left(9\right)

These significant differences possible to increase accuracy at the expense of correct accounting due coefficient backscattering and attenuation coefficient.

The physical principles on which is based the dimensions of the proposed method consist in the fact that the measured power of the echo signals associated with optical characteristics of an inhomogeneous atmosphere known lidar equation. Based on the equations developed new, previously unused computational algorithms for definition of optical characteristics. In these algorithms correctly taken into account influencing factors.

An example implementation of the method (see drawing).

In paragraph 0 place lidar-based FUEL. Radiation probe pulses is performed in the horizontal direction at the working wavelength 0,69 µm in the window of transparency of water vapor. The pulse energy of 0.07 - 0.1 joules. The pulse duration of 30 NS. The distance R₁from the lidar to the point of deviation of the pulse does not exceed 0,3 km Distance between the points of deflection R₁and R₂is 0.1 km Probing inhomogeneous atmosphere is performed in the vertical plane. The promise of the Ute light pulses, which rejects at the point R₁in the direction of the scattering volume 1, receive echo signals that adjust the geometric factor from lidar and accumulate. Send light pulses that are rejected at the point R₂in the direction of the scattering volume 2, receive echo signals that adjust the geometric factor from lidar and accumulate.

For the adopted, adjusted and accumulated echo signals define the characteristics of an inhomogeneous atmosphere τ₁τ₂from the system of equations(3) - (8).

Measurements are desired accuracy when the results of determination of the constant g, obtained by the formulas (3) to (8), does not depend significantly on the position of the scattering volume 1.

Rationale materiality of signs. As follows from the description, each of these features is necessary, and all their indissoluble totality sufficient to achieve a technical result improved measurement accuracy due to more correct account of influencing factors.

Rationale inventive step. The inventive method was analyzed for compliance with the criterion of "inventive step". For this were investigated similar characteristics known in this and related areas of technology. So according to the source [3] was revealed, the characteristic of the reception of the echo signals from the total asciivalues volume of an inhomogeneous atmosphere. However, in this known solution [3] the total scattering volume of the atmosphere belongs tracks sensing, held not less than three noncollinear directions. It is through this realization of the parcels in the atmosphere of light pulses from points separated in space, is achieved technical result of [3]. In the inventive way the common scattering volume of the atmosphere belongs to two tracks sounding, and to determine the transparency of the atmosphere into account the optical thickness of the area enclosed between the points at which rejects pulses.

Thus, in the opinion of the applicants and the proposed solution is the Way multi-position determining optical characteristics of the atmosphere" in their indissoluble totality of symptoms is new, not obvious from the prior art and allows you to get important technical result is to increase the accuracy of definitions at the expense of a more correct account of influencing factors.

Sources of information

1. A. S. No. 966639. The method of determining the optical characteristics of scattering media / N. Sergeev.M., Cogeco M. M., Ashkinadze D. A. Bulletin of inventions No. 38, 1982.

2. A. S. No. 390401. The method of determining the transparency of the atmosphere / Kovalev C. A. Bulletin of inventions No. 30, 1973 (prototype).

3. Patent No. 2439626. The method of determining the transparent the particular atmosphere / Egorov A. D., Potapova, I. A. Bulletin of inventions No. 1, 2012.

The way multi-position determining optical characteristics of the atmosphere in which the parcel in an inhomogeneous atmosphere light pulses of short duration and receiving echo signals; provides correction of the echo signals on the geometric factor lidar; accumulate the adjusted signals within a specified period of time depending on the total length of the investigated area, characterized in that the light pulses reject no less than two points of sounding in the directions for the total scattering volume, and to determine the transparency of the atmosphere into account the optical thickness of the area enclosed between the points at which rejects pulses, define the characteristics of air pollution on accepted and accumulated echo signals.