CN105676231A - Atmospheric temperature inversion method based on rotation Raman laser radar - Google Patents

Abstract

The invention discloses an atmospheric temperature inversion method based on a rotation Raman laser radar. The method comprises the following steps that 1) original data of echo signals of high quantum number and low quantum number rotation Raman channels is read, de-noised and smoothened; 2) a pseudo channel constant C1(z) of the high quantum number of rotation Raman scattering channels is calculated; 3) a backward scattering coefficient beta2 (Jlow, T, z) of the low quantum number of rotation Raman scattering channels is calculated; and 4) a profile T(z) of the atmospheric temperature is solved. According to the atmospheric temperature inversion method based on the rotation Raman laser radar, high quantum number and low quantum number rotation Raman scattering channels are used for solution independently and alternatively, the atmospheric temperature is inversed accurately, an inversion result is not influenced by the intensity and the signal-to-noise ratio of the high quantum number of echo signals of the rotation Raman, the inversion height of the atmospheric temperature is greatly improved, the signal to noise ratio, the stability and the accuracy of detection are higher, and the method is highly consistent with sounding data.

Description

A kind of method based on rotational Raman lidar inverting free air temperature

Technical field

The invention belongs to lidar atmospheric exploration technical field, it is specifically related to a kind of method based on rotational Raman lidar inverting free air temperature.

Background technology

Lidar is a kind of active contemporary optics remote sensing equipment, has the advantage such as high-spatial and temporal resolution and high detectivity, is widely used in 1) free air temperature, humidity and air pressure detection; 2) detection of atmospheric optical parameters; 3) detection of aerosol and plume; 4) detection of atmospheric gas components and concentration and distribution; 5) detection of air wind and turbulent flow.

Raman laser radar is the Raman scattering effect utilizing laser and atmospheric medium, the optics detection means effect of the information such as the density of medium detected by the Raman diffused light of probing medium. Rotational Raman lidar atmospheric temperature detecting technology carrys out atmospheric sounding temperature according to nitrogen in air or the rotational raman scattering intensity of oxygen molecule and the dependence of temperature. Owing to the intensity of the low quantum number of nitrogen molecule and high quantum number rotary Raman spectrum line presents the trend weakening and strengthening respectively with the rising of temperature, rotational Raman lidar utilizes this effect just, realizes the detected with high accuracy to free air temperature by detecting air backscatter signal in these two spectrum line regions. Therefore, rotational Raman lidar has become one of effective technology of atmospheric temperature detecting in troposphere-stratosphere.

At present, utilize the comparatively maturation that rotational Raman lidar Detection Techniques have developed both at home and abroad, but the atmospheric temperature retrieval algorithm that many employings are traditional in the inverting to free air temperature profile, namely utilizes the intensity rate function of high quantum number and low quantum number rotary Raman echoed signal to solve free air temperature. Due to the high difference with low quantum number rotary Raman passage signal to noise ratio (SNR), have impact on the range of detector of free air temperature raman laser radar, meanwhile, in this tradition algorithm, the unstable solution of meter constant A, B and C (or A and B) also will bring error to inversion result. The optimization algorithm of a kind of atmospheric temperature retrieval is proposed for this, this algorithm is utilized can greatly to improve the inverting height of free air temperature, its result has higher detection signal to noise ratio, and detecting error is comparatively stable, reach the inverting requirement of high precision, and with synchronous sounding balloon data, there is good consistence.

Summary of the invention

It is an object of the invention to provide a kind of method based on rotational Raman lidar inverting free air temperature, solve the problem being subject to passage signal to noise ratio difference and meter constant de-stabilising effect existed in existing classical inverse algorithm.

The technical solution adopted in the present invention is, a kind of method based on rotational Raman lidar inverting free air temperature, utilizes the independence of high quantum number and low quantum number rotational raman scattering echoed signal alternately to solve, and obtains the accurate inverting to free air temperature. Specifically according to following step:

Step 1, reading rotary Raman height quantum number and low quantum number passage echoed signal raw data, and carry out denoising and smoothing processing;

Step 2, the pseudo-channel constant C calculating high quantum number rotational raman scattering passage₁(z);

Step 3, the backscattering factor beta calculating low quantum number rotational raman scattering passage₂(J_low, T, z);

Step 4, solve free air temperature profile T (z).

The feature of the present invention is also:

Step 2 calculates the pseudo-channel constant C of high quantum number rotational raman scattering passage₁Z (), is specially:

Step 2.1, utilize klett method and the Fernald method of drawing graceful meticulous inversion method or rice scattering of atmospheric molecule, solve and obtain air Aerosol Extinction profile α (z);

Step 2.2, the backscattering factor beta calculating high quantum number rotational raman scattering passage₁(J_high,t₀(z), z):

${\mathrm{\β}}_1(J_{high},t_0(z),z)=\frac{64{\mathrm{\π}}^4}{15}\×\frac{Ng\left(J_{high}\right){\mathrm{hcB}}_0{({\widetilde{\mathrm{\ν}}}_0+\mathrm{\Δ}{\widetilde{\mathrm{\ν}}}_s(J_{high}\left)\right)}^4{\mathrm{\γ}}^2}{{(2I+1)}^2{k}_B{t}_0\left(z\right)}\×\frac{J_{high}(J_{high}-1)}{(2J_{high}-1)}\×\exp (-\frac{E\left(J_{high}\right)}{k_B{t}_0\left(z\right)});---\left(1\right)$

Wherein, $E_{J_{high}}=\[B_0{J}_{high}(J_{high}+1)-D_0{J}_{high}^2{(J_{high}+1)}^2\]hc,$ G is the statistical weight of core rotation, and h is quantum of action, B₀For molecular rotation constant,For the frequency of incident light, γ is molecular anisotropy, k_BFor Bohr's hereby graceful constant, I is core rotation, and T is the temperature variable solved, t₀Z () is the known free air temperature at synchronous sounding data gained height z place,For Raman frequency shift, E (J_high) be and the high quantum number J of rotation_high, the centrifugal distortion constant D of vibration ground state₀And molecular rotation constant B₀Relevant rotational energy;

Step 2.3, the pseudo-channel constant C solving high quantum number rotational raman scattering passage₁(z):

$C_1\left(z\right)=\frac{P_1(J_{high},t_0(z),z)\×z^2}{{\mathrm{\β}}_1(J_{high},t_0(z),z)\×\exp \[-2\underset{0}{\overset{z}{\∫}}\mathrm{\α}\left(z\right)dz\]};---\left(2\right)$

Wherein, z is height, P₁(J_high,t₀(z), z) it is high quantum number rotational raman scattering echoed signal intensity, constant term C is unrelated with temperature T for this pseudo-channel, comprises laser apparatus launching device parameter, visual telescope receiving trap parameter, the optical efficiency etc. of geometric overlap factor and photodetector efficiency and light path.

Step 3 calculates the backscattering factor beta of low quantum number rotational raman scattering passage₂(J_low, T, z), it is specially:

Assume the pseudo-channel constant C of low quantum number rotational raman scattering passage₂The pseudo-channel constant C of (z) and step 2 gained height quantum number rotational raman scattering passage₁(z) approximately equal, i.e. C₂(z)≈C₁Z (), utilizes formula (3) to calculate the backscattering factor beta of low quantum number rotational raman scattering passage₂(J_low, T, z):

${\mathrm{\β}}_2(J_{low},T,z)=\frac{P_2(J_{low},T,z)\×z^2}{C_2\left(z\right)\×\exp \[-2\underset{o}{\overset{z}{\∫}}\mathrm{\α}\left(z\right)dz\]};---\left(3\right)$

Wherein, P₂(J_low, T, z) and it is low quantum number rotational raman scattering echoed signal intensity.

Step 4 solves free air temperature profile T (z), is specially:

Step 4.1, by variables separation, seek air backscattering factor beta₂(J_low, T, z) with the funtcional relationship of temperature T, represent and be:

$In\[{\mathrm{\β}}_2(J_{low},T,z)\]=In\[M\left(J_{low}\right)\]+In\left(\frac{1}{T\left(z\right)}\right)-\frac{E\left(J_{low}\right)}{k_B}\left(\frac{1}{T\left(z\right)}\right);---\left(4\right)$

Wherein, $M\left(J_{low}\right)=\frac{64{\mathrm{\π}}^4}{15}\×\frac{Ng\left(J_{low}\right){\mathrm{hcB}}_0{({\tilde{v}}_0+\mathrm{\Δ}{\tilde{v}}_s)}^4{\mathrm{\γ}}^2}{{(2I+1)}^2}\×\frac{J_{low}(J_{low}-1)}{(2J_{low}-1)},$

E(J_low) be and the high quantum number J of rotation_low, the centrifugal distortion constant D of vibration ground state₀And molecular rotation constant B₀Relevant rotational energy;

Step 4.2, it is that independent variable(s) accurately solves free air temperature profile T (z) taking 1/T:

$ln\[{\mathrm{\β}}_2(J_{low},T,z)\]=-\frac{1}{2}\frac{1}{T^2\left(z\right)}+\[2-\frac{E\left(J_{low}\right)}{k_B}\]\frac{1}{T\left(z\right)}+(InM-\frac{3}{2});---\left(5\right)$

The invention has the beneficial effects as follows: a kind of method based on rotational Raman lidar inverting free air temperature of the present invention, utilize the independence of high quantum number and low quantum number rotational raman scattering passage alternately to solve, final acquisition is to the accurate inverting of free air temperature:

1) its inversion result is not by the impact that rotary Raman height quantum number echoed signal intensity signal to noise ratio is low;

2) its inverting process avoids the unstable of meter constant;

3) the free air temperature height that inverting obtains improves greatly;

4) algorithm has and better detects signal to noise ratio, stability and accuracy, and has good consistence with sounding data.

Accompanying drawing explanation

Fig. 1 is the schema of a kind of method based on rotational Raman lidar inverting free air temperature of the present invention;

Fig. 2 is the high quantum number of embodiment 1 and the square distance correction signal of low quantum number rotational raman scattering echoed signal;

Fig. 3 is that the utilization tradition algorithm of embodiment 1 and the temperature profile of the inventive method inverting acquisition compare;

Fig. 4 is the high quantum number of embodiment 2 and the square distance correction signal of low quantum number rotational raman scattering echoed signal;

Fig. 5 is that the utilization tradition algorithm of embodiment 2 and the temperature profile of the inventive method inverting acquisition compare.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.

A kind of method based on rotational Raman lidar inverting free air temperature of the present invention, flow process as shown in Figure 1, specifically according to following step:

Step 1, reading rotary Raman height quantum number and low quantum number passage echoed signal raw data, and carry out denoising and smoothing processing;

Step 2, the pseudo-channel constant C calculating high quantum number rotational raman scattering passage₁Z (), is specially:

Step 2.1, utilize klett method and the Fernald method of drawing graceful meticulous inversion method or rice scattering of atmospheric molecule, solve and obtain air Aerosol Extinction profile α (z);

Step 2.2, the backscattering factor beta calculating high quantum number rotational raman scattering passage₁(J_high,t₀(z), z):

${\mathrm{\β}}_1(J_{high},t_0(z),z)=\frac{64{\mathrm{\π}}^4}{15}\×\frac{Ng\left(J_{high}\right){\mathrm{hcB}}_0{({\widetilde{\mathrm{\ν}}}_0+\mathrm{\Δ}{\widetilde{\mathrm{\ν}}}_s(J_{high}\left)\right)}^4{\mathrm{\γ}}^2}{{(2I+1)}^2{k}_B{t}_0\left(z\right)}\×\frac{J_{high}(J_{high}-1)}{(2J_{high}-1)}\×\exp (-\frac{E\left(J_{high}\right)}{k_B{t}_0\left(z\right)});---\left(1\right)$

Wherein, $E_{J_{high}}=\[B_0{J}_{high}(J_{high}+1)-D_0{J}_{high}^2{(J_{high}+1)}^2\]hc,$ G is the statistical weight of core rotation, and h is quantum of action, B₀For molecular rotation constant,For the frequency of incident light, γ is molecular anisotropy, k_BFor Bohr's hereby graceful constant, I is core rotation, and T is the temperature variable solved, t₀Z () is the known free air temperature at synchronous sounding data gained height z place,For Raman frequency shift, E (J_high) be and the high quantum number J of rotation_high, the centrifugal distortion constant D of vibration ground state₀And molecular rotation constant B₀Relevant rotational energy;

Step 2.3, the pseudo-channel constant C solving high quantum number rotational raman scattering passage₁(z):

$C_1\left(z\right)=\frac{P_1(J_{high},t_0(z),z)\×z^2}{{\mathrm{\β}}_1(J_{high},t_0(z),z)\×\exp \[-2\underset{0}{\overset{z}{\∫}}\mathrm{\α}\left(z\right)dz\]};---\left(2\right)$

Wherein, z is height, P₁(J_high,t₀(z), z) it is high quantum number rotational raman scattering echoed signal intensity, constant term C is unrelated with temperature T for this pseudo-channel, comprises laser apparatus launching device parameter, visual telescope receiving trap parameter, the optical efficiency etc. of geometric overlap factor and photodetector efficiency and light path;

Step 3, the backscattering factor beta calculating low quantum number rotational raman scattering passage₂(J_low, T, z), it is specially:

Assume the pseudo-channel constant C of low quantum number rotational raman scattering passage₂The pseudo-channel constant C of (z) and step 2 gained height quantum number rotational raman scattering passage₁(z) approximately equal, i.e. C₂(z)≈C₁Z (), utilizes formula (3) to calculate the backscattering factor beta of low quantum number rotational raman scattering passage₂(J_low, T, z):

${\mathrm{\β}}_2(J_{low},T,z)=\frac{P_2(J_{low},T,z)\×z^2}{C_2\left(z\right)\×\exp \[-2\underset{o}{\overset{z}{\∫}}\mathrm{\α}\left(z\right)dz\]};---\left(3\right)$

Wherein, P₂(J_low, T, z) and it is low quantum number rotational raman scattering echoed signal intensity;

Step 4, solve free air temperature profile T (z), it be specially:

Step 4.1, by variables separation, seek air backscattering factor beta₂(J_low, T, z) with the funtcional relationship of temperature T, represent and be:

$In\[{\mathrm{\β}}_2(J_{low},T,z)\]=In\[M\left(J_{low}\right)\]+In\left(\frac{1}{T\left(z\right)}\right))-\frac{E\left(J_{low}\right)}{k_B}\left(\frac{1}{T\left(z\right)}\right);---\left(4\right)$

Wherein, $M\left(J_{low}\right)=\frac{64{\mathrm{\π}}^4}{15}\×\frac{Ng\left(J_{low}\right){\mathrm{hcB}}_0{({\tilde{v}}_0+\mathrm{\Δ}{\tilde{v}}_s)}^4{\mathrm{\γ}}^2}{{(2I+1)}^2}\×\frac{J_{low}(J_{low}-1)}{(2J_{low}-1)},$

E(J_low) be and the high quantum number J of rotation_low, the centrifugal distortion constant D of vibration ground state₀And molecular rotation constant B₀Relevant rotational energy;

Step 4.2, it is that independent variable(s) accurately solves free air temperature profile T (z) taking 1/T:

$ln\[{\mathrm{\β}}_2(J_{low},T,z)\]=-\frac{1}{2}\frac{1}{T^2}+\[2-\frac{E\left(J_{low}\right)}{k_B}\]\frac{1}{T}+(InM-\frac{3}{2});---\left(5\right)$

Embodiment 1

Experimental result is detected according to 20:00CST in evening on November 5th, 2013, adopt the method inverting free air temperature profile of the present invention, the high quantum number obtained and the range correct quadrature signal (RSCS) of low quantum number rotational raman scattering signal, as shown in Figure 2, that night is fine, effective range of detector of rotational raman scattering height quantum number passage is only about 12km as seen from the figure, and the maximum probe distance of the low quantum number passage of rotational raman scattering can reach about 18km.Tradition algorithm and the inventive method inverting is utilized to obtain free air temperature profile respectively, as shown in Figure 3, in figure, dotted line is the inversion result utilizing tradition algorithm, the visible inverting to free air temperature is highly only 12km, solid line is the free air temperature profile utilizing the inventive method inverting to obtain, and obtains the free air temperature profile of height below 18km. Figure gives the comparison with synchronous sounding data (dotted line) simultaneously there is good consistence. Therefore, utilizing the inventive method to improve the height of the inverting to free air temperature, the free air temperature that its inverting obtains achieves good consistence with synchronous sounding data, demonstrates the feasibility of the inventive method inverting free air temperature.

Embodiment 2

The experimental observed data in night on the 6th November in 2013 is analyzed. Fig. 4 illustrates 19:52CST rotational raman scattering height quantum number passage and low quantum number passage echoed signal square distance correction signal on that night, it is utilized the inversion algorithm inverting free air temperature of the present invention, and gained result and tradition inversion method are compared, as shown in Figure 5. Utilizing the inverting height of tradition algorithm acquisition free air temperature at about 20km (dotted line), more than 20km is bigger with the deviation of sounding temperature data. The inventive method inverting is utilized to obtain the free air temperature profile (solid line) of height 0～25km, and find with the comparison of synchronous sounding balloon temperature data, the temperature profile of the inventive method inverting and sounding data have good consistence at below height 25km, simultaneously also clear show the temperature at height 18km place tropopause and turn back phenomenon. Therefore, utilizing the inventive method inverting can obtain highly higher free air temperature profile, relative deviation is stablized.

The above results shows, utilize the inventive method that the inverting to free air temperature is carried highly greatly, not only can obtain effective detection that tropopause temperature is turned back, its inversion result and sounding data have good consistence, for providing a kind of inversion algorithm reliably based on the above free air temperature in raman laser radar detection troposphere and humidity section.

Claims (6)

1. the method based on rotational Raman lidar inverting free air temperature, it is characterised in that, specifically according to following step:

Step 1, reading rotary Raman height quantum number and low quantum number passage echoed signal raw data, and carry out denoising and smoothing processing;

Step 2, the pseudo-channel constant C calculating high quantum number rotational raman scattering passage₁(z);

Step 3, the backscattering factor beta calculating low quantum number rotational raman scattering passage₂(J_low, T, z);

Step 4, solve free air temperature profile T (z).

2. a kind of method based on rotational Raman lidar inverting free air temperature according to claim 1, it is characterised in that, described step 2 calculates the pseudo-channel constant C of high quantum number rotational raman scattering passage₁(z), specifically according to following step:

Step 2.1, utilize atmospheric molecule draw graceful meticulous inversion method, solve and obtain air Aerosol Extinction profile α (z);

Step 2.2, the backscattering factor beta calculating high quantum number rotational raman scattering passage₁(J_high,t₀(z), z):

Wherein,G is the statistical weight of core rotation, and h is quantum of action, B₀For molecular rotation constant,For the frequency of incident light, γ is molecular anisotropy, k_BFor Bohr's hereby graceful constant, I is core rotation, and T is the temperature variable solved, t₀Z () is the known free air temperature at synchronous sounding data gained height z place,For Raman frequency shift, E (J_high) be and the high quantum number J of rotation_high, the centrifugal distortion constant D of vibration ground state₀And molecular rotation constant B₀Relevant rotational energy;

Step 2.3, the pseudo-channel constant C solving high quantum number rotational raman scattering passage₁(z):

Wherein, z is height, P₁(J_high,t₀Z (), z) is high quantum number rotational raman scattering echoed signal intensity.

3. a kind of method based on rotational Raman lidar inverting free air temperature according to claim 1, it is characterised in that, described step 3 calculates the backscattering factor beta of low quantum number rotational raman scattering passage₂(J_low, T, z), it is specially: the pseudo-channel constant C assuming low quantum number rotational raman scattering passage₂The pseudo-channel constant C of (z) and step 2 gained height quantum number rotational raman scattering passage₁(z) approximately equal, i.e. C₂(z)≈C₁Z (), utilizes formula (3) to calculate the backscattering factor beta of low quantum number rotational raman scattering passage₂(J_low, T, z):

Wherein, P₂(J_low, T, z) and it is low quantum number rotational raman scattering echoed signal intensity.

4. a kind of method based on rotational Raman lidar inverting free air temperature according to claim 1, it is characterised in that, described step 4 solves free air temperature profile T (z), specifically according to following step:

Step 4.1, by variables separation, seek air backscattering factor beta₂(J_low, T, z) with the funtcional relationship of temperature T, represent and be:

Wherein,

E(J_low) be and the high quantum number J of rotation_low, the centrifugal distortion constant D of vibration ground state₀And molecular rotation constant B₀Relevant rotational energy;

Step 4.2, it is that independent variable(s) accurately solves free air temperature profile T (z) taking 1/T:

5. a kind of method based on rotational Raman lidar inverting free air temperature according to claim 2, it is characterised in that, described step 2.1 obtains the klett method that the method for air Aerosol Extinction profile α (z) is meter scattering.

6. a kind of method based on rotational Raman lidar inverting free air temperature according to claim 2, it is characterised in that, described step 2.1 obtains the Fernald method that the method for air Aerosol Extinction profile α (z) is meter scattering.