Method for remote optical probing of weakly scattering atmosphere

FIELD: physics.

SUBSTANCE: light pulses are sent into the atmosphere from points spread in space on crossing probing paths passing in noncollinear directions. Echo signals are received at sending points; light pulses are sent on additional paths, each crossing all previous paths. The total number of paths is not less than five. Characteristics of the atmosphere are determined from the power of said signals using calculation formulae.

EFFECT: high accuracy of determination due to correct accounting for atmospheric background illumination.

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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 optical parameters of weakly scattering atmospheric 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 pulse low duration and registration scattered in the opposite direction of the light converted into electrical signals. These signals accumulate within a specified period of time depending on the total length of the investigated area. Thus amplify the received signals is proportional to the square of the current time counted from the moment of sending of the pulse in the atmosphere.

This known method has low accuracy, because it is based on the assumption of 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.

Closest to the proposed invention is a method of determining the transparency of an inhomogeneous atmosphere [2], which are making the atmosphere light the new impulses from the points posted in space, crossing paths sensing, held not less than three noncollinear directions; with the formation of the field sensing line segments between the points of their intersection, shall receive echo signals at the point of shipment, and the characteristics of the atmosphere is determined by the capacity of these signals using the calculated formulas.

In this known solution improves the accuracy of the characterization of heterogeneous contamination of the atmosphere due to the use of not less than three points make the atmosphere light pulses. However, in solution [2] is not taken into account the background illumination in the process of measuring the properties of weakly scattering atmosphere.

The technical result of the invention is to improve the accuracy of determining the characteristics of the atmosphere due to correctly record the light pollution of the atmosphere.

In the proposed method uses some of the essential features of the prototype, namely: in it are making the atmosphere light pulses of points, spaced, crossing paths sensing, passing through noncollinear directions.

Salient features of the proposed method is that exercised by sending light pulses on more tracks, each of which intersects all before the previous track, with a total of not less than five tracks, and on the accepted signals to determine characteristics of the atmosphere.

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

$$z_i={\{\beta (r_i)\}}^m$$, (1)

found from the system of equations, written for the polygons formed by the intersection of the tracks sounding by noncollinear directions

$$a{}_{i,i}z{}_i-a{}_{i,i+1}{z}_{i+1}=b{}_i,i=1,2\mathrm{that...,}k-1$$(2)

$$a{}_{k,k}z{}_k-a_{k\mathrm{,1}}{z}_1=b_k,$$

where$$a_{i,j}=\sqrt[g]{S_{i,j}}$$,

$$b_i=\pm 2m{\displaystyle \underset{C{}_i}{\int }{\left\{S(R_i,r)\right\}}^{m}dr},$$

$$S_{i,j}=S({\stackrel{\to }{R}}_i,{\stackrel{\to }{r}}_j)=(P_{i,j}-P_{*}(\stackrel{\to }{R{}_i}))/\mathrm{f/mi>\; <mo>\; ,\; </mo>}$$,

S - power signal backscatter adjusted geometric factor lidar$$f$$,

$$P_{i,j}$$- power signal backscattering,

$$f={({\stackrel{\to }{r}}_j-{\stackrel{\to }{R}}_i)}^{-2}$$geometrical factor lidar

β - coefficient backscattering,

σ is the attenuation coefficient,

m=1/g, and is defined and constant g in a power-law relation of the coefficient of the inverse scattering attenuation coefficient β = Dσ^g, (3)

$${\stackrel{\to }{R}}_i$$- the radius vector of the point of sending light pulses and receiving signals, backscattering (i-th location of the transceiver corresponds to the radius-vector$${\stackrel{\to }{R}}_i$$and $$i=\mathrm{1,}\mathrm{2,}\mathrm{...}$$),

$${\stackrel{\to }{r}}_{j_{}}$$is the radius-vector of the sensed scattering element,

$$\stackrel{\to }{r}$$- the current radius-vector of a line passing through the point i, j,

$$c_i$$- segment$$[{\stackrel{\to }{r}}_i,{\stackrel{\to }{r}}_j]$$by which calculates integrals

$$dr$$the element length of the segment.

The invention is illustrated in the drawing. In Fig. 1 presents a diagram of the pulser pulses and receiving echo signals, for example 5 transceivers (lidar).

The method is implemented as follows.

The transceivers 1 - 5 come with diversity in space, in pixels$${\stackrel{\to }{R}}_1$$,$${\stackrel{\to }{R}}_2$$,$${\stackrel{\to }{R}}_3$$,$${\stackrel{\to }{R}}_4$$,$${\stackrel{\to }{R}}_5$$.

Are sending light pulses in the direction of the scattering volume$${\stackrel{\to }{r}}_{1_{}}$$point$${\stackrel{\to }{R}}_1$$,$${\stackrel{\to }{R}}_2$$. Are sending light pulses from point$${\stackrel{\to }{R}}_3$$in the direction of the scattering volume{\stackrel{\to }{r}}_{2_{}}. The route that passes through the points$${\stackrel{\to }{R}}_3$$,$${\stackrel{\to }{r}}_{2_{}}$$crosses two previous trails through the point$${\stackrel{\to }{R}}_1$$,$${\stackrel{\to }{r}}_{1_{}}$$and through the point$${\stackrel{\to }{R}}_2$$,$${\stackrel{\to }{r}}_{1_{}}$$. Are sending light pulses from point$${\stackrel{\to }{R}}_4$$in the direction of the scattering volume$${\stackrel{\to }{r}}_{3_{}}$$. The route that passes through the points$${\stackrel{\to }{R}}_4$$,$${\stackrel{\to }{r}}_{3_{}}$$crosses three previous trails through the point$${\stackrel{\to }{R}}_1$$,$${\stackrel{\to }{r}}_{1_{}}$$through point$${\stackrel{\to }{R}}_2$$,$${\stackrel{\to }{r}}_{1_{}}$$and also through the point$${\stackrel{\to }{R}}_3$$,$${\stackrel{\to }{r}}_{2_{}}$$. Are sending light pulses from point$${\stackrel{\to }{R}}_5$$in the direction of the scattering volume$${\stackrel{\to }{r}}_{4_{}}$$. The route that passes through the points$${\stackrel{\to }{R}}_5$$,$${\stackrel{\to }{r}}_{4_{}}$$crosses the previous four trails through the point$${\stackrel{\to }{R}}_1$$,$${\stackrel{\to }{r}}_{1_{}}$$through point$${\stackrel{\to }{R}}_2$$,$${\stackrel{\to }{r}}_{1_{}}$$

Receive signals at the point of shipment from segments that are limited to the scattering volume. Received echo signals are "adjusted" by the geometrical factor of the lidar. The result is proportional to:

b₁- in the area bounded by the points: $${\stackrel{\to }{r}}_{1_{}}$$ , $${\stackrel{\to }{r}}_{2_{}}$$ ;

b₂- in the area bounded by the points: $${\stackrel{\to }{r}}_{2_{}}$$ , $${\stackrel{\to }{r}}_{3_{}}$$ ;

b₃- in the area bounded by the points: $${\stackrel{\to }{r}}_{3_{}}$$ , $${\stackrel{\to }{r}}_{4_{}}$$ ;

b₄- in the area bounded by the points: $${\stackrel{\to }{r}}_{1_{}}$$ , $${\stackrel{\to }{r}}_{5_{}}$$ ;

b₅- in the area bounded by the points: $${\stackrel{\to }{r}}_{5_{}}$$ , $${\stackrel{\to }{r}}_{6_{}}$$ ;

b₆- in the area bounded by the points: $${\stackrel{\to }{r}}_{}{6}_{}$$ , $${\stackrel{\to }{r}}_{7_{}}$$ ;

b₇- in the area bounded by the points: $${\stackrel{\to }{r}}_{2_{}}$$ , $${\stackrel{\to }{r}}_{5_{}}$$ ;

b₈- in the area bounded by the points: $${\stackrel{\to }{r}}_{5_{}}$$ , $${\stackrel{\to }{r}}_{8_{}}$$ ;

b₉- in the area bounded by the points: $${\stackrel{\to }{r}}_{8_{}}$$ , $${\stackrel{\to }{r}}_{9_{}}$$ ;

b₁₁- in the area bounded by the points: $${\stackrel{\to }{r}}_{6_{}}$$ , $${\stackrel{\to }{r}}_{8_{}}$$ ;

b₁₂- in the area bounded by the points: $${\stackrel{\to }{r}}_{8_{}}$$ , $${\stackrel{\to }{r}}_{{10}_{}}$$ ;

b₁₃- in the area bounded by the points: $${\stackrel{\to }{r}}_{4_{}}$$ , $${\stackrel{\to /mo>}{r}}_{7_{}}$$ ;

b₁₄- in the area bounded by the points: $${\stackrel{\to }{r}}_{7_{}}$$ , $${\stackrel{\to }{r}}_{9_{}}$$ ;

b₁₅- in the area bounded by the points: $${\stackrel{\to }{r}}_{9_{}}$$ , $${\stackrel{\to }{r}}_{{10}_{}}$$ .

Values of z_ifound from the system of equations (2). For this specific example find the solution of systems of equations:

$$a_{11}{z}_1-a_{12}{z}_2=b_1,$$

$$a_{12}{z}_2-a_{13}{z}_3=b_2,$$

$$a_{13}{z}_3-a_{14}{z}_4=b_3,$$

$$a_{21}{z}_1-a_{25}{z}_5=b_4,$$

$$a_{25}{z}_5-a_{26}{z}_6=b_5,$$

$$a_{26}{z}_6-a_{27}{z}_7=b_6,$$

$$a_{32}z2-a_{35}{z}_5=b_7,$$ (4)

$$a_{35}{z}_5-a_{38}{z}_8=b_8,$$

$$a_{38}{z}_8-a_{39}{z}_9=b_9,$$

$$a_{43}{z}_3-a_{46}{z}_6=b_{10},$$

$$a_{46}{z}_6-a_{48}{z}_8=b_{11},$$

$$a_{48}{z}_8-a_{\mathrm{4,10}}{z}_{10}=b_{12},$$

$$a_{54}{z}_4-a_{57}{z}_7=b_{13},$$

$$a_{57}{z}_7-a_{59}{z}_9=b_{14},$$

$$a_{59}{z}_9-a_{\mathrm{5,10}}{z}_{10}=b_{15},$$

moreover, these significant differences allow to improve the accuracy of accounting 5 unknown capacities of the background illumination of the closed system of 15 equations for them and 10 of unknown optical the x characteristics of atmospheric aerosol.

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 the atmosphere known lidar equation taking into consideration the background illumination. 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.

In paragraphs $${\stackrel{\to }{R}}_1$$ , $${\stackrel{\to }{R}}_2$$ , $${\stackrel{\to }{R}}_3$$ , $${\stackrel{\to }{R}}_4$$ , $${\stackrel{\to }{R}}_5$$ located on one straight line, place the lidar 1 - 5 on the basis of LEVI. Radiation probe pulses is carried out at a working wavelength 0,69 µm in the window of transparency of water vapor. Energy and the pulse is 0.07 - 0.1 joules. The pulse duration of 30 NS. The distance between neighboring lidar does not exceed 0.5 km Probing inhomogeneous atmosphere is performed in the vertical plane passing through the line placement lidar. Are sending light pulses lidar 1 on the highway that passes through the points $${\stackrel{\to }{R}}_1$$ , $${\stackrel{\to }{r}}_{1_{}}$$ , lidar 2 - through point $${\stackrel{\to }{R}}_2$$ , $${\stackrel{\to }{r}}_{1_{}}$$ ; lidar 3 - through point $${\stackrel{\to }{R}}_3$$ , $${\stackrel{\to }{r}}_{2_{}}$$ ; lidar 4 - through point $${\stackrel{\to }{R}}_4$$ , $${\stackrel{\to }{r}}_{3_{}}$$ ; lidar 5 - through point $${\stackrel{\to }{R}}_5$$ , $${\stackrel{\to }{r}}_{4_{}}$$ .

The route that passes through the points $${\stackrel{\to }{R}}_3$$ , $${\stackrel{\to }{r}}_{2_{}}$$ crosses two previous trails through the point $${\stackrel{\to }{R}}_1$$ , $${\stackrel{\to }{r}}_{1_{}}$$ and through the point $${\stackrel{\to }{R}}_2$$ , $${\stackrel{}{r}}_{1_{}}$$ . The route that passes through the points $${\stackrel{\to }{R}}_4$$ , $${\stackrel{\to }{r}}_{3_{}}$$ crosses three previous trails through the point $${\stackrel{\to }{R}}_1$$ , $${\stackrel{\to }{r}}_{1_{}}$$ through point $${\stackrel{\to }{R}}_2$$ , $${\stackrel{\to }{r}}_{1_{}}$$ and through the point $${\stackrel{\to }{R}}_3$$ , $${\stackrel{\to }{r}}_{2_{}}$$ . The route that passes through the points $${\stackrel{\to }{R}}_5$$ , $${\stackrel{\to }{r}}_{4_{}}$$ crosses the previous four trails through the point $${\stackrel{\to }{R}}_1$$ , $${\stackrel{\to }{r}}_{1_{}}$$ through point $${\stackrel{\to }{R}}_2$$ , $${\stackrel{\to }{r}}_{1_{}}$$ through point $${\stackrel{\to }{R}}_3$$ , $${\stackrel{\to }{r}}_{2_{}}$$ and through the point $${\stackrel{}{\mathrm{R\; <mo\; stretchy="true">\; \to \; </mo>}}}_4$$ , $${\stackrel{\to }{r}}_{3_{}}$$ .

At the point of shipment shall receive echo signals:

in point of $${\stackrel{\to }{R}}_1$$ from cuts, limited points: $${\stackrel{\to }{r}}_{1_{}}$$ , $${\stackrel{\to }{r}}_{2_{}}$$ and $${\stackrel{\to }{r}}_{2_{}}$$ , $${\stackrel{\to }{r}}_{3_{}}$$ and $${\stackrel{\to }{r}}_{4_{}}$$ , $${\stackrel{\to }{r}}_{3_{}}$$ ;

in point of $${\stackrel{\to }{R}}_2$$ from cuts, limited points: $${\stackrel{\to }{r}}_{1_{}}$$ , $${\stackrel{\to }{r}}_{5_{}}$$ and $${\stackrel{\to }{r}}_{5_{}}$$ , $${\stackrel{\to }{r}}_{6_{}}$$ and $${\stackrel{\to }{r}}_{6_{}}$$ , $${\stackrel{\to }{r}}_{7_{}}$$ ;

in point of $${\stackrel{\to }{R}}_3$$ from cuts, limited point is: $${\stackrel{\to }{r}}_{2_{}}$$ , $${\stackrel{\to }{r}}_{5_{}}$$ and $${\stackrel{\to }{r}}_{5_{}}$$ , $${\stackrel{\to }{r}}_{8_{}}$$ and $${\stackrel{\to }{r}}_{8_{}}$$ , $${\stackrel{\to }{r}}_{9_{}}$$ ;

in point of $${\stackrel{\to }{R}}_4$$ from cuts, limited points: $${\stackrel{\to }{r}}_{3_{}}$$ , $${\stackrel{\to }{r}}_{6_{}}$$ and $${\stackrel{\to }{r}}_{6_{}}$$ , $${\stackrel{\to }{r}}_{8_{}}$$ and $${\stackrel{\to }{r}}_{8_{}}$$ , $${\stackrel{\to }{r}}_{{10}_{}}$$ ;

in point of $${\stackrel{\to }{R}}_5$$ from cuts, limited points: $${\stackrel{\to }{r}}_{4_{}}$$ , $${\stackrel{\to }{r}}_{7_{}}$$ and $${\stackrel{\to }{r}}_{7_{}}$$ , $${\stackrel{\to }{r}}_{9_{}}$$ and $${\stackrel{\to }{r}}_{9_{}}$$ , $${\stackrel{\to }{r}}_{{10}_{}}$$ .

Accepted and corrected echo signals accumulate. define the characteristics of an inhomogeneous atmosphere z_ifrom the system of equations (4).

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 scattering volume of an inhomogeneous atmosphere. However, in this known solution [3] the total scattering volume of the atmosphere which s belongs tracks sensing, passing at least 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 are sending light pulses on more tracks, each of which intersects all the previous tracks, with a total of at least five runs.

Thus, according to the applicant, and the authors, the proposed solution method for determining the transparency of the atmosphere in its 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. 390401. The method for determining atmospheric transparency/

Kovalev V.A. - Bulletin of inventions No. 30, 1973.

2. A.S. No. 1597815 A1, MKI 5 G01W1/00. The method of determining the attenuation of the atmosphere/ Egorov A.D., Emelyanova VN- Publ. 07.10.90, Bulletin of inventions No. 37 (prototype).

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

The way stantsionnogo optical sensing weakly scattering atmosphere by sending into the atmosphere light pulses on crossing paths, passing through noncollinear directions, receiving back-scattered signals, determining the characteristics of the atmosphere on the capacity of these signals using the calculated formulas, characterized in that are sending light pulses on more tracks, each of which intersects all the previous tracks, a total of not less than five tracks, and on the accepted signals to determine characteristics of the atmosphere.