Method for identifying and detecting height of atmospheric boundary layer based on coherent Doppler laser radar

Abstract

The invention relates to the technical field of atmospheric layer height detection, in particular to a coherent Doppler laser radar-based atmospheric boundary layer height identification and detection method, which comprises the following steps of: transmitting a laser beam through a coherent Doppler laser radar to obtain echo original radial wind speed data under different azimuth angles; performing inversion operation on the echo original radial wind speed data to obtain three-dimensional wind field information; horizontal wind speed is extracted from the three-dimensional wind field information, and turbulence intensity is obtained through calculation; and performing cubic root gradient calculation on the turbulence intensity, and selecting the height corresponding to the minimum value of the cubic root gradient calculation result, namely the height of the atmospheric boundary layer. According to the method, the accurate atmospheric boundary layer height with high time resolution and high spatial resolution can be obtained, so that the problems of large detection height limitation, poor continuity, poor time resolution, poor spatial resolution, limited deployment, low accuracy and the like in an existing atmospheric boundary layer observation mode are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of atmospheric layer height detection, and in particular to an identification and detection method for the atmospheric boundary layer height based on a coherent Doppler laser radar. Background Art

[0002] The atmospheric boundary layer is a key interface between the atmosphere and the surface, and its dynamic changes are crucial to understanding and predicting weather and climate phenomena. The height changes of the atmospheric boundary layer not only reflect the complex interaction between the surface and the atmosphere, but also directly affect the diffusion of pollutants and the transfer of energy (for example: ground heating during the day causes air convection to form a mixing layer (i.e., an area with active turbulence), which makes the boundary layer thicker; at night, the ground begins to cool due to the lack of direct heating from the sun, causing the boundary layer to become stable and shallow; this periodic change (i.e., the change in the boundary layer between day and night) affects the behavior of pollutants in the atmosphere. Pollutants may be confined to a shallow mixing layer at night, resulting in increased concentrations, which can have adverse effects on human health); in addition, the structure of the boundary layer is crucial to the accuracy of climate models, and continuous observation of the boundary layer height is an effective way to study changes in the boundary layer. Therefore, it is of great significance to continuously obtain high temporal and spatial resolution and accurate boundary layer height observation data.

[0003] At present, the observation methods of atmospheric boundary layer height include: 1. Meteorological observation towers, which can provide data with high temporal and spatial resolution, are suitable for studying atmospheric fluctuations within a certain boundary height range. When the boundary layer height rises due to turbulence, it exceeds the upper limit of observation and cannot provide information on the higher atmosphere; 2. Radiosonde: This method can obtain atmospheric profile data from the surface to high altitudes. However, due to cost and manpower investment, it can usually only be launched once or twice a day, and the configuration sites are limited, so it is impossible to obtain continuous, long-term, high-spatial-resolution, and high-coverage atmospheric boundary layer observation data; 3. Mie scattering lidar: This method has high temporal and spatial resolution and long detection distance, and can effectively obtain continuous atmospheric boundary layer observation data. However, the lidars widely used at present mostly use the threshold method. When there are clouds or vertical aerosol distribution in the atmosphere, it is difficult to identify the atmospheric boundary layer using the threshold method, and the boundary layer height inversion results have large deviations and poor accuracy. 4. The variance method of inverting boundary height based on coherent lidar GNR. This method solves the height of the boundary layer according to the variance change of GNR in a given time window. However, this method has a relatively low time resolution and cannot fully utilize the high time resolution of lidar. 5. The threshold method based on the inversion boundary height of the coherent laser radar GNR. This method determines the height of the atmospheric boundary layer according to the breakthrough value of the GNR vertical profile. Under different weather conditions, the error is large. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in order to solve the technical problem of low temporal and spatial resolution and low accuracy of the existing atmospheric boundary layer height recognition and detection method, the present invention provides an atmospheric boundary layer height recognition and detection method based on coherent Doppler laser radar, which can improve the temporal resolution, spatial resolution and accuracy of the atmospheric boundary layer height by improving the atmospheric boundary layer height recognition and detection method.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar, comprising the following steps: S1, emitting a laser beam through a coherent Doppler laser radar to obtain echo raw radial wind speed data at different azimuth angles; S2, obtaining the original radial wind speed data of the echo in step S1, and performing an inversion operation on the original radial wind speed data of the echo to obtain three-dimensional wind field information; S3, obtaining the three-dimensional wind field information in step S2, and extracting the horizontal wind speed from the three-dimensional wind field information, and obtaining the turbulence intensity by calculation; S4. Obtain the turbulence intensity in step S3, perform cube root gradient calculation on the turbulence intensity, and select the height corresponding to the minimum value of the cube root gradient calculation result, which is the atmospheric boundary layer height.

[0006] Therefore, by obtaining the original radial wind speed data of the echo at different azimuths of the coherent Doppler lidar, and inverting the original radial wind speed data of the echo, the three-dimensional wind field information is obtained, and the horizontal wind speed is extracted, and the turbulence intensity is calculated by the horizontal wind speed. The cube root gradient is then calculated for the turbulence intensity, and the height corresponding to the minimum value of the cube root gradient is selected as the atmospheric boundary layer height. The accurate, high temporal resolution, and high spatial resolution atmospheric boundary layer height can be obtained to solve the problems of large detection height limitation, poor continuity, poor temporal resolution, poor spatial resolution, limited deployment, and low accuracy in the existing atmospheric boundary layer observation methods. It is helpful to understand the atmospheric transmission mechanism and atmospheric microphysical processes, and is effectively applied to meteorological disaster prevention monitoring, aviation safety assurance, and environmental pollution control. It is of great significance in the fields of meteorology, aviation, and environment.

[0007] Furthermore, in step S1, the coherent Doppler laser radar rotates eight azimuths in sequence within a set time interval to obtain the original radial wind speed data of the echo at each azimuth; wherein: eight azimuths correspond to eight original radial wind speed data of the echo. Thus, obtaining the original radial wind speed data of the echo at eight azimuths can provide more dense spatial sampling points, thereby achieving more precise and accurate three-dimensional wind field reconstruction; it can improve the redundancy of the data (that is, if a certain azimuth data is lost, the other azimuth data can still reconstruct the wind field), and improve the reliability of the system.

[0008] Furthermore, in step S2, an eight-beam singular value matrix decomposition method is used and the data is simplified to obtain three-dimensional wind field information.

[0009] Further, in step S2, the radial velocity matrix The calculation formula is: ; It can be expressed as: ; Singular value matrix The expression is: ; in: Three-dimensional wind field matrix, represents the radial velocity at each azimuth angle, is the angle of a certain azimuth, is the elevation angle.

[0010] Furthermore, it is characterized in that, in step S2, the three-dimensional wind field matrix The expression is: ; Decomposing the matrix to solve the three-dimensional wind field : ; in: Three-dimensional wind field Direction of wind speed, Three-dimensional wind field Direction of wind speed, Three-dimensional wind field Direction of wind speed.

[0011] Further, in step S3, the horizontal wind speed standard deviation The calculation formula is: ; Average horizontal wind speed The calculation formula is: ; Where: n is the number of data values.

[0012] Further, in step S3, the end flow intensity The calculation formula is: .

[0013] Further, in step S4, the end flow intensity Cube root gradient The calculation formula is: .

[0014] Further, in step S4, the atmospheric boundary layer height The calculation formula is: .

[0015] Compared with the prior art, the present invention has the following beneficial effects: By acquiring the original radial wind speed data of the echo at different azimuths of the coherent Doppler lidar, and inverting the original radial wind speed data of the echo, the three-dimensional wind field information is obtained, and then the horizontal wind speed is extracted, and the turbulence intensity is calculated by the horizontal wind speed. The cube root gradient is then calculated for the turbulence intensity, and the height corresponding to the minimum value of the cube root gradient is selected as the atmospheric boundary layer height. The accurate, high temporal resolution, and high spatial resolution atmospheric boundary layer height can be obtained to solve the problems of large detection height limitation, poor continuity, poor temporal resolution, poor spatial resolution, limited deployment, and low accuracy in the existing atmospheric boundary layer observation methods. It is helpful to understand the atmospheric transmission mechanism and atmospheric microphysical processes, and is effectively applied to meteorological disaster prevention monitoring, aviation safety assurance, and environmental pollution control. It is of great significance in the fields of meteorology, aviation, and environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0017] Figure 1 It is a flow chart of the method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar of the present invention; Figure 2 The eight azimuths of the present invention Schematic diagram of Figure 3 is the elevation angle of the present invention Schematic diagram of . DETAILED DESCRIPTION

[0018] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention.

[0019] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0020] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] like Figures 1 to 3 As shown in the figure, it is the best embodiment of the present invention. The method for identifying and detecting the atmospheric boundary layer height based on the coherent Doppler laser radar in this embodiment comprises the following steps: S1, emitting a laser beam through a coherent Doppler laser radar to obtain echo raw radial wind speed data at different azimuth angles; S2, obtaining the original radial wind speed data of the echo in step S1, and performing an inversion operation on the original radial wind speed data of the echo to obtain three-dimensional wind field information; S3, obtaining the three-dimensional wind field information in step S2, and extracting the horizontal wind speed from the three-dimensional wind field information, and obtaining the turbulence intensity by calculation; S4, obtain the turbulence intensity in step S3, and perform a cube root gradient calculation on the turbulence intensity, select the height corresponding to the minimum value of the cube root gradient calculation result, and the height is the atmospheric boundary layer height. Thus, by obtaining the original radial wind speed data of the echo under different azimuths of the coherent Doppler laser radar, and inverting the original radial wind speed data of the echo, extract the horizontal wind speed after obtaining the three-dimensional wind field information, and calculate the turbulence intensity by the horizontal wind speed, and then calculate the cube root gradient for the turbulence intensity, select the height corresponding to the minimum value of the cube root gradient as the atmospheric boundary layer height, and obtain an accurate atmospheric boundary layer height with high temporal resolution and high spatial resolution, so as to solve the problems of large detection height limit, poor continuity, poor temporal resolution, poor spatial resolution, limited deployment, and low accuracy in the existing atmospheric boundary layer observation method, it is helpful to understand the atmospheric transmission mechanism and atmospheric microphysical process, and effectively apply to the fields of meteorological disaster prevention monitoring, aviation safety and environmental pollution control, and it is of great significance in the fields of meteorology, aviation and environment.

[0022] In other words, the method of observing the atmospheric boundary layer based on coherent Doppler lidar has high temporal resolution and can meet the requirements of atmospheric boundary layer observation altitude. In addition, it can also obtain effective atmospheric boundary layer observation information. The mechanical automated scanning mode does not require excessive manpower investment, can achieve continuous long-term observation, and the equipment deployment is flexible. The cubic root gradient method is used for solution, which can filter out the influence of clouds or uneven spatial distribution of aerosols on the lidar signal, and the inversion result has low deviation and high accuracy. From the perspective of atmospheric turbulence, the atmospheric boundary layer is the contact between turbulent motion and non-turbulent motion. The theory is solid and reliable, and the atmospheric boundary layer height solved using turbulence intensity is more accurate.

[0023] Specifically, the use of coherent Doppler lidar can realize multiple scanning modes such as PPI, DBS, and RHI, which can improve different observation data and thus fully understand the dynamic changes of the atmospheric boundary layer; coherent Doppler lidar can perform multiple high-frequency scans to obtain high temporal resolution, and the lidar beam width is narrow, which can perform accurate measurements at a smaller spatial resolution and provide data with high spatial resolution and high temporal resolution; in addition, coherent Doppler lidar has a long working distance and can cover a large spatial range to observe atmospheric boundary layer structures at different height levels; eight beams are used to solve the three-dimensional wind field to obtain more dense spatial sampling points, and to achieve more precise and accurate three-dimensional wind field reconstruction, thereby achieving high-accuracy atmospheric boundary layer observation.

[0024] It should be noted that: 1. Temporal resolution refers to the time interval between atmospheric boundary layer height measurements at the same location, i.e., the temporal frequency of sampling; 2. Spatial resolution refers to the difference or accuracy obtained when measuring the atmospheric boundary layer height at different geographical locations. This parameter reflects the spatial variation characteristics of the atmospheric boundary layer height; 3. In meteorological radar observation, radial velocity refers to the wind speed corresponding to the phase difference between the reflected echo received by the radar and the radar transmission wave. It reflects the radial movement rate of airflow in the atmosphere toward the radar station. The original radial wind speed of the echo refers to the direct measurement result of the radial velocity before further processing or interpretation. 4. Three-dimensional wind field information refers to the physical quantity in which the wind vector (including wind speed and wind direction) changes with the spatial position and time in three-dimensional space. In the fields of meteorology, atmospheric science, environmental science, etc., three-dimensional wind field information is of great significance for understanding atmospheric movement, predicting weather changes, and evaluating wind energy resources.

[0025] In this embodiment, in step S1, the coherent Doppler laser radar rotates eight azimuths in sequence within a set time interval to obtain the original radial wind speed data of the echo at each azimuth; wherein: eight azimuths correspond to eight original radial wind speed data of the echo. Thus, obtaining the original radial wind speed data of the echo at eight azimuths can provide more dense spatial sampling points, thereby achieving more precise and accurate three-dimensional wind field reconstruction; it can improve the redundancy of the data (that is, if a certain azimuth data is lost, the other azimuth data can still reconstruct the wind field), and improve the reliability of the system.

[0026] Specifically, Figure 2 As shown, the eight azimuth angles mean that the coherent Doppler laser radar rotates continuously for one circle (i.e. 360°), and the azimuth angles are 45° apart.

[0027] In this embodiment, in step S2, eight-beam singular value matrix decomposition is used and data is simplified to obtain three-dimensional wind field information; radial velocity matrix The calculation formula is: ; It can be expressed as: ; Singular value matrix The expression is: ; in: Three-dimensional wind field matrix, represents the radial velocity at each azimuth angle, is the angle of a certain azimuth (such as Figure 2 As shown, θ1=45°, θ2=90°, θ3=135°, θ4=180°, θ5=225°, θ6=270°, θ7=345°, θ8=360°), is the elevation angle; 3D Wind Field Matrix The expression is: ; Decomposing the matrix to solve the three-dimensional wind field : ; in: Three-dimensional wind field Direction of wind speed, Three-dimensional wind field Direction of wind speed, Three-dimensional wind field Specifically, the radial velocity at different azimuth angles is equal to the matrix product of the elevation angle, azimuth angle singular value matrix and the three-dimensional wind field.

[0028] In this embodiment, in step S3, the horizontal wind speed The calculation formula is: ; Horizontal wind speed standard deviation The calculation formula is: ; Average horizontal wind speed The calculation formula is: ; Where: n is the number of data values; End flow strength The calculation formula is: .

[0029] Specifically, the turbulence intensity is calculated using the horizontal wind speed solution. The turbulence intensity is defined as the ratio of the horizontal wind speed standard deviation to the horizontal wind speed average value, and is used to characterize the intensity of wind speed fluctuations.

[0030] In this embodiment, in step S4, the end flow intensity Cube root gradient The calculation formula is: ; Atmospheric boundary layer height The calculation formula is: .

[0031] Specifically, choose the cube root gradient The height corresponding to the minimum value of the contour line is the atmospheric boundary layer height , which is also the turbulence intensity The altitude where the gradient changes the most and decays the fastest; the location of the atmospheric boundary layer is to find the turbulence intensity The location where the vertical gradient changes significantly is calculated by Cube root gradient The vertical gradient of the atmospheric boundary layer reaches its minimum value near the top of the atmospheric boundary layer. Therefore, the minimum value of the vertical gradient is used as a landmark to determine the height of the atmospheric boundary layer.

[0032] In summary, the present invention obtains the original radial wind speed data of the echo at different azimuths of the coherent Doppler laser radar, and inverts the original radial wind speed data of the echo to obtain the three-dimensional wind field information, then extracts the horizontal wind speed, and calculates the turbulence intensity through the horizontal wind speed, and then calculates the cube root gradient of the turbulence intensity, and selects the height corresponding to the minimum value of the cube root gradient as the atmospheric boundary layer height, which can obtain accurate, high temporal resolution, and high spatial resolution atmospheric boundary layer height, so as to solve the problems of large detection height limitation, poor continuity, poor temporal resolution, poor spatial resolution, limited deployment, and low accuracy in the existing atmospheric boundary layer observation method, which is helpful to understand the atmospheric transmission mechanism and atmospheric microphysical process, and is effectively applied to the fields of meteorological disaster prevention monitoring, aviation safety and environmental pollution control, and has great significance in the fields of meteorology, aviation and environment.

[0033] The above description is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar, characterized in that: The following steps are involved: S1, emitting a laser beam through a coherent Doppler laser radar to obtain echo raw radial wind speed data at different azimuth angles; S2, obtaining the original radial wind speed data of the echo in step S1, and performing an inversion operation on the original radial wind speed data of the echo to obtain three-dimensional wind field information; S3, obtaining the three-dimensional wind field information in step S2, and extracting the horizontal wind speed from the three-dimensional wind field information, and obtaining the turbulence intensity by calculation; S4. Obtain the turbulence intensity in step S3, perform cube root gradient calculation on the turbulence intensity, and select the height corresponding to the minimum value of the cube root gradient calculation result, which is the atmospheric boundary layer height.

2. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S1, the coherent Doppler laser radar rotates eight azimuth angles in sequence within a set time interval to obtain the original radial wind speed data of the echo at each azimuth angle; Among them: eight azimuths correspond to eight echo original radial wind speed data.

3. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S2, an eight-beam singular value matrix decomposition method is used and the data is simplified to obtain three-dimensional wind field information.

4. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S2, the radial velocity matrix The calculation formula is: ； It can be expressed as: ； Singular value matrix The expression is: ； in: Three-dimensional wind field matrix, represents the radial velocity at each azimuth angle, is the angle of a certain azimuth, is the elevation angle.

5. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S2, the three-dimensional wind field matrix The expression is: ； Decomposing the matrix to solve the three-dimensional wind field : ； in: Three-dimensional wind field Direction of wind speed, Three-dimensional wind field Direction of wind speed, Three-dimensional wind field Direction of wind speed.

6. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S3, the horizontal wind speed The calculation formula is: 。 7. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S3, the horizontal wind speed standard deviation The calculation formula is: ； Average horizontal wind speed The calculation formula is: ； Where: n is the number of data values.

8. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S3, the end flow strength The calculation formula is: 。 9. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S4, the end flow strength Cube root gradient The calculation formula is: 。 10. The method for identifying and detecting the atmospheric boundary layer height based on coherent Doppler laser radar according to claim 1, characterized in that: In step S4, the atmospheric boundary layer height The calculation formula is: 。

Images