Wide-area atmospheric wind field detection system and method based on forward scattering

Abstract

This application relates to a wide-area atmospheric wind field detection system based on forward scattering, comprising: a ground-based laser emission system, including a laser and a scanning device, which is arranged on the ground; and a space-based optical receiving system, including a receiving telescope and an optical receiver device, which is arranged on an airborne platform. And a wide-area atmospheric wind field detection method based on forward scattering is provided for the above system, including: emitting a laser into the air at a set angle backward of the airborne platform after the scanning device detects it; wherein, the laser generates a forward scattering signal through the forward scattering effect of atmospheric particles; using the receiving telescope and the optical receiver device to receive the forward scattering signal at a specified angle; and generating wind field data according to the forward scattering signal. The airborne platform only carries a receiver, which can reduce the requirements for the load and power consumption of the satellite platform, and the deployment of the laser on the ground can reduce the platform limitations. Moreover, the satellite receives the forward scattering signal, avoiding the atmospheric attenuation of the return of the echo signal, which is beneficial to improving the signal-to-noise ratio and detection accuracy.

Description

Technical Field

[0001] The present application relates to the technical field of atmospheric wind field detection, and in particular to a wide-area atmospheric wind field detection system and method based on forward scattering. Background Art

[0002] The atmospheric wind field is one of the main parameters of the atmosphere, and the observation of the atmospheric wind field is an important basis for carrying out weather forecasting and long-term climate change prediction. At the same time, with the increasing proportion of domestic wind power installed capacity year by year, the operation uncertainty of the power system increases, and the requirements for the numerical prediction timeliness and accuracy of the wind field are also continuously improving.

[0003] In the prior art, the ground-based lidar detection technology is relatively mature and most widely used. It mainly uses the backscattering signal of atmospheric particles as the echo signal source for atmospheric detection. The laser emission end and the telescope receiving end of this type of lidar are at the same position. The laser will be affected by the atmosphere during both the emission and backscattering processes and undergo energy attenuation. Therefore, when performing upper atmosphere detection, the energy attenuation is severe, resulting in a decrease in the signal-to-noise ratio. In addition, the detection range of the ground-based lidar is limited. When performing regional atmospheric detection, a large number of networks need to be combined for joint detection.

[0004] Refer to Figure 1 , when the laser emitted by the ground-based lidar travels in the atmosphere, it is attenuated by the atmosphere on the transmission path (mainly from the extinction of atmospheric aerosols and air molecules). At the same time, a part of the laser scattered by the atmospheric aerosols and air molecules returns along the original path and is again attenuated by the atmosphere on the transmission path, and finally is received by the lidar.

[0005] The ground-based lidar detection has deficiencies in coverage and measurement capabilities. The advantages of satellites are reflected in their ability to provide high-resolution, high-quality, near-real-time three-dimensional wind profile data on a global scale. Spaceborne lidar is one of the important means for global-scale atmospheric detection. However, due to the limitations of the operating orbit and operating mechanism, the data of a single spaceborne lidar cannot accurately describe the regional atmospheric conditions. Taking the Aelus spaceborne wind lidar as an example, this type of system uses a detection technology route of a 150 mJ pulsed laser and a large-aperture receiving analog detection mechanism of 1.5 m, which brings the characteristics of large system volume, heavy weight, high cost, and high risk. The orbital operation period of this lidar is 7 days. To obtain an effective vertical profile, data accumulation with a horizontal resolution of 87 km and a vertical resolution of 250 m is required, and it is not easy to obtain regional and refined atmospheric measurement data.

[0006] Refer to Figure 2, the laser emission position of the spaceborne lidar is different from that of the ground-based lidar. The height of the detection target from the ground is z, and the satellite orbit height is 600 km. Similar to the ground-based lidar detection, both the laser emission end and the telescope receiving end of the spaceborne lidar are carried on the satellite. It also uses the backscattering signal of atmospheric particles as the echo signal source. Therefore, the signal will be attenuated by the atmosphere during both the laser emission and the scattering return processes. However, compared with the ground-based lidar, the spaceborne lidar has more advantages in detecting the upper atmosphere.

[0007] The successful experience of the Aelus spaceborne wind lidar shows that the spaceborne wind measurement technology has the ability to obtain a large-scale wind field. However, currently, the spaceborne wind measurement technology is also restricted by the satellite platform. For example, in the Aelus spaceborne wind lidar, the satellite only carries one effective payload, the ALADIN. The total weight of the satellite exceeds 1 ton, and it still fails to reach its predetermined technical indicators; the backscattering results in a relatively low signal-to-noise ratio and a relatively coarse spatio-temporal resolution; the spatial coverage density of a single satellite is still relatively low, and at the same time, the satellite cost is high. Summary of the Invention

[0008] This application provides a wide-area atmospheric wind field detection system based on forward scattering, including: a ground-based laser emission system, including a laser and a scanning device, which is set on the ground; a space-based optical receiving system, including a receiving telescope and an optical receiver device, which is set on an airborne platform; wherein, after the scanning device detects the airborne platform, it emits a laser into the air at a set angle backward. The laser generates a forward scattering signal through the forward scattering effect of atmospheric particles, and uses the receiving telescope and the optical receiver device to receive the forward scattering signal at a specified angle, and generates wind field data according to the forward scattering signal.

[0009] In one embodiment, the forward scattering angle range is from 1° to 20°.

[0010] In one embodiment, the laser can emit lasers with wavelengths of 355 nm and 1064 nm.

[0011] This application also provides a wide-area atmospheric wind field detection method based on forward scattering, including: emitting a laser into the air at a set angle backward after the scanning device detects the airborne platform; wherein, the laser generates a forward scattering signal through the forward scattering effect of atmospheric particles; using the receiving telescope and the optical receiver device to receive the forward scattering signal at a specified angle; preprocessing the forward scattering signal to extract the Doppler shift frequency sequence of the preprocessed forward scattering signal; correcting the Doppler shift frequency sequence according to the orbital velocity and attitude parameters of the airborne platform; performing atmospheric attenuation compensation processing on the corrected Doppler shift frequency sequence according to real-time meteorological parameters; generating wind speed information according to the Doppler shift frequency sequence after atmospheric attenuation compensation processing.

[0012] In one embodiment, the laser can emit lasers with wavelengths of 355 nm and 1064 nm; among them, the 355-nm band is used for Rayleigh scattering signals to retrieve the upper-middle atmosphere wind field above 10 km; the 1064-nm band is used for Mie scattering signals to retrieve the middle-lower atmosphere wind field from the boundary layer to the lower troposphere.

[0013] In one embodiment, the preprocessing of the forward scattering signal includes: using the time gating technique to filter out background noise by setting an effective time window to generate a signal sequence after background noise filtering. , and the specific formula is as follows:

[0014]

[0015] Among them, is the original signal intensity; , are the start and end times of the effective signal.

[0016] In one embodiment, extracting the Doppler shift frequency sequence of the preprocessed forward scattering signal includes: using the dual-edge frequency discrimination technique to measure the light intensity values of the signals output by two channels of the frequency discriminator to generate a light intensity ratio, and calculating the Doppler shift amount according to the light intensity ratio. The specific formula is as follows:

[0017]

[0018]

[0019] Among them, , are the signal intensities received by the two channels of the frequency discriminator; is the Doppler shift rate sequence; is the ratio of the two-channel signals; is the reference ratio under windless conditions; G is the frequency shift proportionality coefficient, which is determined by instrument calibration.

[0020] In one embodiment, the formula for correcting the Doppler shift frequency sequence according to the orbital velocity and attitude parameters of the empty platform is as follows:

[0021]

[0022] Among them, is the corrected Doppler shift frequency sequence; is the orbital velocity of the empty platform; λ is the laser wavelength; α is the angle between the moving velocity vector of the empty platform and the laser propagation direction.

[0023] In one embodiment, the formula for compensating the atmospheric attenuation of the corrected Doppler shift frequency sequence using the radiation transfer model according to real-time meteorological parameters is as follows:

[0024]

[0025] Among them, is the frequency shift sequence after atmospheric attenuation compensation; is the atmospheric optical thickness; L is the length of the signal transmission path from laser emission to the reception by the airborne platform.

[0026] In one embodiment, wind speed information is generated according to the Doppler frequency shift sequence after atmospheric attenuation compensation processing, including: calculating the radial wind speed based on the Doppler effect, and the specific formula is:

[0027]

[0028] Among them, is the radial wind speed, with the unit of m / s; is the included angle between the laser emission direction and the reception direction of the airborne platform.

[0029] The present application adopts the above method and has the following beneficial effects:

[0030] 1. The airborne platform only carries a receiver, which can effectively reduce the requirements for the load and power consumption of the satellite platform; the laser is deployed on the ground, which can reduce the platform limitations, use dual wavelengths of 355nm and 1064nm for detection, and provide laser power and pulse repetition frequency, thereby reducing the aperture and weight of the telescope carried by the satellite;

[0031] 2. The scattering intensity of forward scattering within a certain angular range (1° to 20°) is 10 - 100 times that of backward scattering. The satellite receives the forward scattering signal of single-pass extinction, avoiding the atmospheric attenuation when the echo signal returns, which is beneficial to improving the signal-to-noise ratio and detection accuracy, and reducing the requirements for low telescopes and detectors;

[0032] 3. The satellite only carries a telescope and a detector, which can effectively reduce costs and technical risks and facilitate the realization of satellite collaborative network observation;

[0033] 4. Through small satellite network observation, the spatio-temporal resolution and coverage rate of the wind profile can be improved, and the observation accuracy can be improved by using collaborative observation inversion, and the inversion of the three-dimensional wind field can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of a ground-based lidar detection system in one embodiment;

[0035] Figure 2 is a schematic diagram of a spaceborne lidar detection system in one embodiment;

[0036] Figure 3Schematic diagram of a wide-area atmospheric wind field detection system based on forward scattering in an embodiment;

[0037] Figure 4 Flowchart of a wide-area atmospheric wind field detection method based on forward scattering in an embodiment;

[0038] Figure 5 Schematic diagram of the vertical distribution profile of the extinction coefficients of atmospheric aerosols and gas molecules in an embodiment;

[0039] Figure 6 Schematic diagram of the simulated signals of ground-air detection and ground-based detection in an embodiment;

[0040] Figure 7 Schematic diagram of the simulated signals of ground-air detection and spaceborne detection in an embodiment. Detailed implementation manners

[0041] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0042] The relevant terms in the present application are explained as follows:

[0043] Forward scattering: The phenomenon that the propagation direction of the scattered light forms an angle less than 90° with the incident light direction after the laser beam interacts with atmospheric particles.

[0044] ATP system (acquisition, pointing, tracking): A control system in which a ground laser station adjusts the laser emission direction in real time through an optoelectronic sensor and a servo mechanism to align with the satellite field of view.

[0045] Dual-edge F-P etalon: A high-precision frequency discriminator that inversely calculates the wind speed by measuring the frequency shift of the Rayleigh scattering signal.

[0046] Multi-angle radial wind synthesis: A technology that uses multiple satellites to observe the same area from different azimuth angles and obtains a three-dimensional wind field through vector synthesis.

[0047] Space-ground integrated collaborative networking: A system architecture in which a ground laser station and a space-based satellite group work together to achieve continuous detection of a wide-area wind field.

[0048] The present application provides a wide-area atmospheric wind field detection system based on forward scattering, including: a ground-based laser emission system, including a laser and a scanning device, which is arranged on the ground; a space-based optical receiving system, including a receiving telescope and an optical receiver device, which is arranged on an airborne platform; wherein, after the scanning device detects the airborne platform, it emits a laser into the air at a set angle backward, the laser generates a forward scattering signal through the forward scattering effect of atmospheric particles, and the receiving telescope and the optical receiver device are used to receive the forward scattering signal at a specified angle, and wind field data is generated according to the forward scattering signal.

[0049] In one embodiment, the forward scattering angle range is from 1° to 20°.

[0050] In one embodiment, the laser can emit lasers with wavelengths of 355 nm and 1064 nm.

[0051] In the present application, the airborne platform includes a satellite platform, an aircraft and a stratospheric airship platform.

[0052] Taking the satellite platform as an example, aiming at the characteristics of the small satellite platform, a new type of space-ground integrated collaborative regional wind field measurement system is established. By separating the light source and the receiving end, using the ground-based laser emission and the satellite-borne detection to receive the forward scattering signal, the detection of the regional wind field is realized.

[0053] Specifically, referring to Figure 3 , the lidar telescope and the subsequent unit are carried on the satellite, and the satellite orbit altitude is 300 km. The 355 nm laser is deployed on the ground, and the laser direction points to the satellite. Assuming the angle between the laser and the satellite is , and the height of the detection target (atmospheric molecules and aerosol particles) from the ground is z, the design of the whole system is as follows:

[0054] 1. Design of the spaceborne detector: The middle and upper layer winds are measured by using the Rayleigh scattering signal of the atmosphere in the 355 nm band, and the middle and lower layer winds are measured by using the Mie scattering signal of aerosols and thin clouds in the 1064 nm band. Among them, the atmospheric scattering signal in the 355 nm band is stronger, and the clear sky atmospheric scattering in the 1064 nm band is weaker. Using different bands for different detection objects is beneficial to improving the signal-to-noise ratio. At the same time, when the satellite detector does not receive the scattering signal of the ground actively emitted laser, it can also be used as a passive detector to perform single-point detection of clouds, and realize regional coverage by using satellite network observation.

[0055] According to requirements, detectors with 2 bands can be carried on one satellite at the same time and share 1 telescope, or single-band detectors and multi-angle telescopes can be carried only.

[0056] 2. Ground station design: The ground station is mainly composed of a laser emission unit and an ATP (capture, alignment, tracking) unit. The laser emission unit consists of a laser and a telescope, etc. The pulse repetition rate is planned to be above 100 Hz to improve the horizontal spatial resolution. When a satellite passes by, the ATP unit tracks the position of the passing satellite and directs the laser beam emitted by the laser emission unit into the field of view of the satellite detector, so that the satellite detector can receive forward scattered signals from the atmosphere, aerosols or thin clouds.

[0057] 3. Network detection design: Network detection includes ground station networking and satellite networking. According to the positions of ground stations and satellites, the direction of the laser beam emitted from the ground is planned. Combined with the changes in the observation field of view of different satellites, radial wind measurement at different azimuths, altitudes and horizontal positions can be achieved. Combined with multi-satellite collaborative inversion and regional assimilation, high-temporal and high-precision regional wind field inversion can be achieved.

[0058] In this system, the light source part with the highest weight requirement is placed at the ground station, and the satellite is only equipped with a receiver, which can effectively reduce the load and power consumption requirements of the satellite platform; the deployment of the laser on the ground can reduce the restrictions of the platform, use 355nm and 1064nm dual wavelengths for detection, and provide laser power and repetition rate, so as to reduce the aperture of the satellite-borne telescope and reduce the weight; the satellite receives the forward scattering signal with one-way extinction, which is beneficial to improve the signal-to-noise ratio and detection accuracy, and reduce the requirements for low telescopes and detectors; in the present application scheme, the satellite is only equipped with a telescope and a detector, which can effectively reduce costs and technical risks, and facilitate the realization of collaborative networking observation of small satellites; the spatiotemporal resolution and coverage of wind profiles can be improved through small satellite networking observations, and the collaborative observation inversion can be used to improve the observation accuracy, and the inversion of three-dimensional wind fields can be realized.

[0059] When detecting the atmosphere in a certain area, ground-to-air joint detection has advantages that the above two radar systems do not have. Compared with ground-based lidar, which requires a large-scale network, ground-to-air joint detection only needs to deploy lasers in the area to be detected where the satellite passes, and the temporal and spatial resolution of regional detection is also higher than that of satellite-based lidar.

[0060] Since the laser emission and reception are not at the same end, the forward scattering signal of the particles can be fully utilized. According to the Lorentz-Mie scattering model, the scattering intensity of forward scattering within a certain angle range (1° to 20°) is 10-100 times that of backscattering. In addition, since the reception of forward scattering signals avoids the atmospheric attenuation of the return echo signal, the signal intensity received by the ground-to-air joint detection is superior to that of satellite-borne detection, and deploying the laser on the ground can effectively reduce the load pressure, which is conducive to the later system maintenance.

[0061] In addition, the present application makes relevant designs for the optical system and the detector as shown in Table 1 and Table 2 below:

[0062] Table 1 Optical System Related Design

[0063]

[0064] Table 2 Detector Related Design

[0065]

[0066] For the above system, referring to Figure 4 , this application also provides a wide-area atmospheric wind field detection method based on forward scattering, including:

[0067] S101, After the scanning device detects the empty platform, emit laser into the air at a set angle; wherein, the laser generates a forward scattering signal through the forward scattering effect of atmospheric particles;

[0068] S201, Use the receiving telescope and optical receiver device to receive the forward scattering signal at a specified angle;

[0069] S301, Preprocess the forward scattering signal and extract the Doppler shift frequency sequence of the preprocessed forward scattering signal;

[0070] S401, Correct the Doppler shift frequency sequence according to the orbit velocity and attitude parameters of the empty platform;

[0071] S501, Use the radiation transfer model to perform atmospheric attenuation compensation processing on the corrected Doppler shift frequency sequence according to real-time meteorological parameters;

[0072] S601, Generate wind speed information according to the Doppler shift frequency sequence after atmospheric attenuation compensation processing.

[0073] This application is based on the Doppler shift principle, calculates the wind speed through the frequency shift amount of the forward scattering signal, combines satellite orbit velocity correction to eliminate platform motion interference. Adopt the multi-angle radial wind synthesis technology (multiple satellites cooperate to observe data at different azimuth angles), combine with the atmospheric dynamics model to invert the three-dimensional wind field vector.

[0074] During the laser emission process, the ground station emits high-energy laser to form a beam suitable for forward scattering detection. The key parameters are as follows: Laser source: High-power Nd:YAG solid-state laser (355nm / 1064nm); Pulse energy: >1J; Pulse repetition frequency: >30Hz; Beam divergence angle: <0.1mrad; Beam pointing and tracking system (ATP): Adjust the laser angle in real time to align with the satellite detection window.

[0075] The satellite is equipped with a telescope and a detector, which receives forward scattered light signals within a specified angle (adjustable from 0 to 30°; theoretically, the smaller the angle, the stronger the intensity, but in reality it is affected by optical and mechanical conditions, so 5° is optimal).

[0076] In one embodiment, the laser can emit lasers with wavelengths of 355nm and 1064nm; the 355nm band is used for Rayleigh scattering signals to invert the middle and high-level wind fields above 10km; the 1064nm band is used for Mie scattering signals to invert the middle and low-level wind fields from the boundary layer to the lower troposphere.

[0077] In one embodiment, preprocessing the forward scattered signal includes: using time gating technology to filter out background noise by setting an effective time window to generate a signal sequence after the background noise is filtered out. , the specific formula is as follows:

[0078]

[0079] in, is the original signal strength; , It is the start and end time of the effective signal.

[0080] In one embodiment, extracting the Doppler shift frequency sequence of the pre-processed forward scattered signal includes: using the double edge frequency detection technology to measure the light intensity values ​​of the output signals of the two channels of the frequency detector, generating a light intensity ratio, and calculating the Doppler frequency shift amount according to the light intensity ratio. The specific formula is as follows:

[0081]

[0082]

[0083] in, , The received signal strength of the two channels of the discriminator; is the Doppler frequency shift rate sequence; is the ratio of the two channel signals; It is the reference ratio under windless conditions; G is the frequency shift proportional coefficient, which is determined by instrument calibration.

[0084] In one embodiment, the formula for correcting the Doppler shift frequency sequence according to the orbital velocity and attitude parameters of the unloaded platform is as follows:

[0085]

[0086] in, is the corrected Doppler shift frequency sequence; is the track speed of the no-load platform; λ is the laser wavelength; α is the angle between the movement speed vector of the no-load platform and the laser propagation direction.

[0087] In one embodiment, the formula for compensating the atmospheric attenuation of the corrected Doppler frequency shift frequency sequence according to the real-time meteorological parameters using the radiative transfer model is as follows:

[0088]

[0089] Wherein, is the frequency shift sequence after atmospheric attenuation compensation; is the atmospheric optical thickness; L is the length of the signal transmission path from laser emission to the no-load platform reception.

[0090] Wherein, the radiative transfer model is MODTRAN, which is used to determine the attenuation coefficient.

[0091] In one embodiment, the low-level error is controlled within ≤2 m / s, and the high-level error is controlled within ≤5 m / s.

[0092] In one embodiment, wind speed information is generated according to the Doppler frequency shift frequency sequence after atmospheric attenuation compensation, including: calculating the radial wind speed according to the Doppler effect, and the specific formula is:

[0093]

[0094] Wherein, is the radial wind speed, with the unit of m / s; is the angle between the laser emission direction and the no-load platform reception direction.

[0095] Refer to Figures 1 to 3 For the system shown, relevant simulations are given in this application. Specifically, the expressions for the backscattering coefficients of gas molecules and atmospheric aerosol particles used in the simulation calculation:

[0096]

[0097] Wherein, and are the backscattering coefficients of air molecules and atmospheric aerosol particles respectively; is the wavelength of the detection target (atmospheric molecules and aerosol particles); z is the height of the detection target (atmospheric molecules and aerosol particles) from the ground; their extinction coefficients and can be obtained by multiplying their respective backscattering coefficients by the extinction backscattering ratio; the extinction backscattering ratios of air molecules and atmospheric aerosol particles are 8 / 3 and 50 respectively.

[0098] Refer to Figure 5, according to the above formula, the vertical distribution profiles of the extinction coefficients of atmospheric aerosols and gas molecules simulated and calculated in this application are in the altitude range of 0 - 100 km, and the laser wavelength is selected as 355 nm. It can be seen from the figure that the extinction coefficient of near-surface atmospheric aerosols is greater than that of gas molecules until the altitude of about 4 km. Further upward, the extinction coefficient of atmospheric aerosols is always less than that of gas molecules. Secondly, in the altitude range of 0 - 30 km, the extinction coefficient of gas molecules attenuates from 10 -2 km -1 to less than 10 -3 km -1 , and the dynamic range is within 2 orders of magnitude. While the extinction coefficient of atmospheric aerosols attenuates from 10 -1 km -1 to 10 -5 km -1 , reaching more than 4 orders of magnitude. It can be seen that the attenuation rate of the extinction coefficient of atmospheric aerosols with altitude is significantly greater than that of gas molecules. Thirdly, the extinction coefficient of gas molecules almost shows a linear attenuation with altitude, while the extinction coefficient of atmospheric aerosols has a minimum value near the tropopause and shows an increasing trend in the stratosphere.

[0099] The simulation parameter inputs are shown in Table 3. The selection of these technical parameters is mainly based on four considerations: First, the technical parameters of domestic and foreign similar lidars are used as references; second, the simulation calculation results obtained with different technical parameters are compared and the technical parameters are optimized; third, the lidar development technology that has been mastered is utilized; fourth, the technical parameters of various commonly used device products at the current stage on the market are used as the basis.

[0100] Table 3 Simulation Parameters

[0101]

[0102] Refer to Figure 6 and Figure 7 , and according to the above atmospheric models and lidar parameters, the signal intensities of radars with different detection systems are calculated under the same atmospheric conditions and radar parameters. It can be seen from the figure that in the altitude range of 3 km - 30 km, the number of echo photons of the ground-based detection decreases from 106km -1 to 102km -1 , and the dynamic range is 4 orders of magnitude; while when the angle between the satellite and the laser is 5° and 15°, the number of echo photons of the ground-air combined detection decreases from 103km -1 to 101km -1, the dynamic range is two orders of magnitude. At the same time, as the altitude increases, the number of echo photons detected by the two radar systems becomes closer. The simulated echo photon numbers of spaceborne detection and space-air combined detection are comparable in magnitude. Under the existing atmospheric model and radar parameter conditions, due to the strong forward scattering of low-level aerosols, the signal of space-air combined detection is one order of magnitude stronger than that of spaceborne detection when the satellite-laser angle is 5° and 15° at an altitude of 0 - 7 km; in areas with low aerosol content, the signal of spaceborne detection is slightly stronger than that of space-air combined detection. In addition, as the detection angle decreases, the forward scattering effect of aerosol particles becomes stronger, the echo signal in this area is also stronger, and some distribution characteristics of aerosols can be reflected.

[0103] The above-described embodiments merely represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the appended claims.

Claims

1. A wide-area atmospheric wind field detection system based on forward scattering, characterized in that: include: The ground-based laser emission system, including a laser and a scanning device, is located on the ground; The space-based optical receiving system includes a receiving telescope and an optical receiver device, which is installed on an airborne platform; Among them, after the scanning device detects the empty platform, a laser is emitted into the air at a set angle. The laser generates a forward scattering signal through the forward scattering effect of atmospheric particles, and the forward scattering signal is received at a specified angle using a receiving telescope and an optical receiver device, and wind field data is generated based on the forward scattering signal.

2. The system according to claim 1, characterized in that The forward scatter angle ranges from 1° to 20°.

3. The system according to claim 1, characterized in that The laser can emit laser light at 355nm and 1064nm wavelengths.

4. A wide-area atmospheric wind field detection method based on forward scattering, characterized in that: include: After the scanning device detects the empty platform, the laser is emitted into the air at a set angle; wherein the laser generates a forward scattering signal through the forward scattering effect of atmospheric particles; receiving the forward scattered signal at a specified angle using a receiving telescope and an optical receiver device; Preprocessing the forward scattered signal, extracting the Doppler shift frequency sequence of the preprocessed forward scattered signal; Correct the Doppler shift frequency sequence according to the orbital velocity and attitude parameters of the airborne platform; According to the real-time meteorological parameters, the radiation transmission model is used to perform atmospheric attenuation compensation processing on the corrected Doppler shift frequency sequence; The wind speed information is generated according to the Doppler shift frequency sequence after atmospheric attenuation compensation.

5. The method according to claim 4, characterized in that The laser can emit lasers with wavelengths of 355nm and 1064nm; the 355nm band is used for Rayleigh scattering signals to invert the middle and high-level wind fields above 10km; the 1064nm band is used for Mie scattering signals to invert the middle and low-level wind fields from the boundary layer to the lower troposphere.

6. The method according to claim 4, characterized in that Preprocessing of the forward scattered signal includes: using time gating technology to filter out background noise by setting an effective time window, and generating a signal sequence after background noise is filtered out. , the specific formula is as follows: in, is the original signal strength; , It is the start and end time of the effective signal.

7. The method according to claim 6, characterized in that Extracting the Doppler shift frequency sequence of the pre-processed forward scattered signal includes: using the double edge frequency discrimination technology, measuring the light intensity values ​​of the output signals of the two channels of the discriminator, generating a light intensity ratio, and calculating the Doppler frequency shift amount according to the light intensity ratio. The specific formula is as follows: in, , The received signal strength of the two channels of the discriminator; is the Doppler frequency shift rate sequence; is the ratio of the two channel signals; It is the reference ratio under windless conditions; G is the frequency shift proportional coefficient, which is determined by instrument calibration.

8. The method according to claim 7, characterized in that The formula for correcting the Doppler shift frequency sequence according to the orbital velocity and attitude parameters of the airborne platform is as follows: in, is the corrected Doppler shift frequency sequence; is the orbital velocity of the unloaded platform; λ is the laser wavelength; α is the angle between the velocity vector of the unloaded platform and the laser propagation direction.

9. The method according to claim 8, characterized in that The formula for atmospheric attenuation compensation of the corrected Doppler shift frequency sequence using the radiation transmission model according to real-time meteorological parameters is as follows: in, is the frequency shift sequence after atmospheric attenuation compensation; is the atmospheric optical thickness; L It is the length of the signal transmission path between the laser emission and the reception on the airborne platform.

10. The method according to claim 9, characterized in that The wind speed information is generated according to the Doppler frequency shift frequency sequence after atmospheric attenuation compensation, including: calculating the radial wind speed according to the Doppler effect, the specific formula is: in, is the radial wind speed, in m / s; It is the angle between the laser emission direction and the receiving direction of the unloaded platform.

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