Double-layer rapid stream identification method based on wind measurement laser radar

Abstract

The invention discloses a double-layer rapid stream identification method based on a wind measurement laser radar. The method comprises the following steps: (1) acquiring horizontal wind speed profile data of the wind measurement laser radar in a preset time period; (2) time-height two-dimensional connected domain detection is carried out on the horizontal wind speed profile data, and candidate torrent connected domains are screened; (3) torrent core parameters including the torrent axis height, the maximum wind speed and the torrent upper boundary height are extracted; (4) calculating the maximum wind speed difference and the wind speed gradient of each time point, setting a wind speed difference threshold value and a gradient threshold value, and screening an effective torrent layer; (5) dynamically grading the torrent intensity based on the maximum wind speed and the wind speed difference of the effective torrent layer; the reliability of the identification result is improved.

Description

Technical Field

[0001] The present invention relates to the field of laser radar technology, and in particular to a double-layer jet stream identification method based on wind laser radar. Background Art

[0002] As a zonal airflow with significantly enhanced wind speed in the atmospheric boundary layer, the low-level jet has significant vertical wind shear characteristics and a typical diurnal variation pattern. The formation and maintenance of the low-level jet are related to the coupled development with the high and low-level circulations, and it is one of the core dynamic mechanisms that trigger mesoscale severe convective systems and extreme precipitation events. Traditional research has focused on the contribution of a single low-level jet (such as the weather-scale low-level jet SLLJ or the boundary layer jet BLJ) to heavy rain. However, observations in recent years have shown that double low-level jets (i.e., the synergistic coupling of SLLJ and BLJ) can significantly amplify the intensity of heavy rain through multi-level dynamic-thermal coupling effects, but its mechanism of action has not been fully revealed, and there are significant gaps in related detection technologies.

[0003] At present, the main means of observing low-level jets are radiosondes and wind profiler radars. However, general radiosondes are only conducted twice a day, and their temporal resolution is extremely low, which cannot capture the continuous evolution characteristics and daily variation characteristics of the jet stream. Although wind profiler radar provides a higher temporal resolution, its vertical resolution is relatively limited (usually on the order of hundreds of meters), and the data is easily disturbed in complex terrain and heavy precipitation environments. In addition, strong gusts in the near-ground layer caused by afternoon thermal convection are prone to produce instantaneous wind speed maxima, and their wind field characteristics are highly similar to those of real low-level jets. Therefore, it is easy to show characteristics similar to low-level jets in the observation data, which leads to misjudgment. Summary of the invention

[0004] Purpose of the invention: The purpose of the present invention is to provide a double-layer jet identification method based on wind measuring lidar, which can realize the real-time extraction of low-altitude jet core parameters through connected domain identification algorithm and high-precision vertical wind speed profile analysis, effectively identify double-layer low-altitude jets and filter out abnormal wind speed fluctuations, thereby reducing the false alarm rate.

[0005] Technical solution: The double-layer jet stream identification method based on wind laser radar described in the present invention comprises the following steps: (1) Obtain horizontal wind speed profile data from the wind laser radar within a preset time period; (2) Perform time-height two-dimensional connected domain detection on horizontal wind speed profile data to screen candidate jet stream connected domains. (3) Extract the core parameters of the jet stream, including the jet stream axis height, maximum wind speed, and jet stream upper boundary height; (4) Calculate the maximum wind speed difference and wind speed gradient at each time point, set the wind speed difference threshold and gradient threshold, and screen the effective jet layer; (5) Dynamically classify the jet stream intensity based on the maximum wind speed and wind speed difference of the effective jet layer.

[0006] Furthermore, in step (2), the specific steps are as follows: setting the altitude range for low-altitude jet stream identification and maximum wind speed threshold , traverse the time-height wind speed data, mark the pixels that meet the maximum wind speed threshold as candidate areas; scan the candidate areas point by point, based on the time window threshold and the height window threshold, allow the wind speed to be discontinuous in the window, and mark the same connected domain; filter out short-term disturbances and isolated noise through the time span threshold and the pixel area threshold, and obtain the final candidate jet connected domain.

[0007] Furthermore, in step (2), the time window threshold and the height window threshold allow the connected domain to be interrupted by no more than 3 consecutive time points in the time dimension and no more than 5 consecutive height layers in the height dimension, respectively.

[0008] Furthermore, in step (3), the number of connected domains of the vertical section at each time point is detected; the maximum wind speed point of each connected domain and the corresponding jet axis height are determined; the minimum wind speed value is found between the jet axis height and the search upper boundary, and the jet upper boundary height is determined; Furthermore, in step (3), the maximum wind speed point of each connected domain is determined by a local extreme value detection algorithm, and pseudo extreme values ​​caused by noise are eliminated.

[0009] Furthermore, in step (3), if there is only a single connected domain, then at the jet axis height to Find the minimum wind speed to determine the upper boundary height .

[0010] Furthermore, in step (4), the maximum wind speed difference at each time point in vertical height is calculated: With wind speed gradient , the calculation formula is as follows: ; ; in, is the maximum wind speed in the effective jet layer, is the corresponding height position; is the minimum wind speed above, is the corresponding height position.

[0011] Furthermore, in step (5), the dynamic classification type of rapids intensity is: Type 1: and It is a weak rapid; Type 2: and It is a moderate rapid; Type 3: and It is a strong rapids; Type 4: and It is a super rapid.

[0012] An electronic device described in the present invention includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is loaded into the processor, any one of the methods for identifying a double-layer jet stream based on a wind laser radar is implemented.

[0013] A storage medium described in the present invention stores a computer program, characterized in that when the computer program is executed by a processor, any one of the methods for identifying a double-layer jet stream based on a wind laser radar is implemented.

[0014] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: The present invention can effectively identify the double-layer jet structure in the low-altitude atmosphere through the time-altitude two-dimensional connected domain detection method, combined with wind speed extreme value analysis and jet core parameter extraction. Compared with traditional methods, this method can not only capture a single jet layer, but also accurately locate the double-layer low-altitude jet with complex stratification characteristics, providing more accurate data support for low-altitude wind field structure research and atmospheric dynamics analysis; the present invention effectively filters out short-term sudden wind speed anomaly areas by setting the spatiotemporal continuity detection conditions and combining wind speed gradient screening, avoiding the mistaken identification of local short-term strong gusts as low-altitude jets, and improving the reliability of the identification results. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process of the present invention; Figure 2 It is the vertical profile diagram of wind speed of the present invention; Figure 3 This is the first effect diagram of double-layer rapids identification of the present invention; wherein, Figure 3 (a) is the traditional method; Figure 3 (b) is the method of the present invention; Figure 4 This is the second effect diagram of double-layer rapids identification of the present invention; wherein, Figure 4 (a) is the traditional method; Figure 4 (b) is the method of the present invention. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0017] like Figure 1As shown, an embodiment of the present invention provides a method for identifying low-altitude jet streams based on a wind laser radar, comprising the following steps: Step S1: Obtain horizontal wind speed profile data within a certain period of time ,in Represents time and altitude respectively. Represent the corresponding time index and height index respectively.

[0018] Step S2: Horizontal wind speed profile data Perform time-height two-dimensional connected domain detection and preliminarily screen candidate rapids connected domains. The following steps are included: S21, set the altitude range for low-altitude jet stream identification , set the maximum wind speed threshold of the jet stream , traverse the time-height two-dimensional wind speed data and identify all wind speed areas that meet the preset maximum wind speed threshold. At the same time, create a jet stream marker matrix , the area that meets the condition of being greater than the preset maximum wind speed threshold is marked as 1, and the area that does not meet the condition is marked as 0, which is used to subsequently number the identified jet stream connected domains.

[0019] S22, preliminary screening of candidate rapids areas. and minimum altitude Start scanning all the pixels of the wind speed data point by point. When a jet point with a wind speed greater than the preset threshold and not marked is found, it is used as the starting point of the new connected domain for search. During the search process, the pixel point window threshold of the time dimension of the connected domain is set. Pixel window threshold with height dimension , allowing the maximum wind speed to be in the time dimension pixel window Pixel window with height dimension There are discontinuities in the range. When the maximum wind speed does not meet the condition of being greater than the preset wind speed threshold within the preset time step and height step, it can still be considered to belong to the same connected domain to better adapt to the non-uniform change characteristics of the low-level jet. Finally, all connected pixels are marked with the same connected domain number to complete the preliminary screening of the jet area.

[0020] S23, screening effective jet stream connected domains. In order to avoid the impact of short-term strong gusts, the spatiotemporal continuity of the extracted wind speed area is detected. The detection method is: setting the connected domain detection time window , the time span is less than the preset connected domain detection time window The connected domain is filtered out to eliminate the influence of short-term disturbance on the recognition results, and the strong wind caused by strong gusts with instantaneous wind speed reaching the jet stream standard is initially filtered out. Set the connected domain area threshold , the connected domain pixel area is less than the preset connected domain area threshold The regions of the rapids are filtered out to remove the pseudo-connected domains formed by isolated noise points. After the above screening, the final candidate rapids connected domain is obtained.

[0021] Step S3: Based on the determined candidate jet stream connected domain, further extract the jet stream core parameters, including the jet stream axis height , Maximum wind speed , height of the upper boundary of the jet stream . The following steps are included: S31, according to Matrix, for each time point The number of connected domains is detected on the vertical section of the wind speed profile to determine the number of connected domains of the wind speed profile at that moment. According to the number, they are marked as the first connected domain, the second connected domain, etc.

[0022] S32, performing extreme value detection in the first connected domain and the second connected domain respectively to determine the first maximum wind speed point in each connected domain and the second maximum wind speed point , define its height as the first jet axis height and the second jet stream axis high speed .

[0023] S33, at the height of the first jet axis and the height of the second jet axis Find the minimum wind speed between , and determine the corresponding height , is defined as the candidate first jet upper boundary height. and the upper search boundary Find the minimum wind speed between , and determine the corresponding height , is determined as the candidate upper boundary height of the second jet.

[0024] When there is only one connected domain in S31, namely the first connected domain, then at the height of the first jet axis To the upper limit of the search Find the minimum wind speed between , and determine the corresponding height , is defined as the upper boundary height of the candidate jet stream.

[0025] Step S4: Based on the jet stream parameters initially extracted in step S3, the maximum wind speed difference at each time point in vertical height is calculated. With wind speed gradient , the calculation formula is as follows: ; ; in, is the maximum wind speed in the effective jet layer, is the corresponding height position; is the minimum wind speed above, is the corresponding height position.

[0026] To ensure the physical plausibility of the jet stream, a wind speed difference threshold is set. and wind speed gradient threshold , perform data screening: only keep the wind speed difference Greater than or equal to the preset threshold The jet layer is designed to ensure that the intensity of the jet meets the characteristic requirements; Keep only wind speed gradient Less than or equal to the preset threshold jet layer to avoid misjudgment due to high wind speed gradients formed by interfering signal points.

[0027] Finally, the connected jet domains that meet the above screening criteria are identified as effective jet layers and used for further analysis.

[0028] Step S5: The final effective jet layer and its maximum wind speed confirmed in step S4 Wind speed difference The intensity of the rapids is dynamically classified to determine the type of rapids; the types of dynamic classification of rapids intensity are: Type 1: and It is a weak rapid; Type 2: and It is a moderate rapid; Type 3: and It is a strong rapids; Type 4: and It is a super rapid.

[0029] Embodiment 1: The present invention proposes a double-layer jet stream identification method based on wind laser radar, which analyzes horizontal wind speed observation data and includes the following steps: Step S1: Obtain horizontal wind speed profile data within a certain period of time ,in Represents time and altitude respectively. Represent the corresponding time index and height index respectively.

[0030] Step S2: Horizontal wind speed profile data Perform time-height two-dimensional connected domain detection and preliminarily screen candidate rapids connected domains. The following steps are included: S21, set the altitude range for low-altitude jet stream identification , set the maximum wind speed threshold of the jet stream In this example, the low-altitude jet stream identification height interval is set to [100m, 3500m], and the maximum wind speed threshold of the jet stream is 10m / s. Traverse the time-height wind speed pixel points and identify the area where the wind speed is greater than or equal to 10m / s. Create a jet stream marker matrix , the area that meets the condition of being greater than the preset maximum wind speed threshold is marked as 1, and the area that does not meet the condition is marked as 0, which is used to subsequently number the identified jet stream connected domains.

[0031] S22, from the initial moment and minimum altitude Start by scanning the wind speed data point by point to find the wind speed that meets The pixels that are not marked with numbers are retrieved as the starting point of the new connected domain. and height step threshold If the wind speed value within the range is not greater than 10m / s, it can still be considered to belong to the same connected domain. All pixels that meet the conditions are marked as the same connected domain and assigned a unique number.

[0032] S23, in order to avoid the influence of short-term strong gusts, the temporal and spatial continuity of the extracted wind speed area is detected to screen the effective jet area. The detection method is: In this embodiment, a connected domain detection time window is set , remove the connected domains whose time span is less than In the area, strong winds with instantaneous wind speeds reaching jet stream standards caused by short-term strong gusts are initially filtered out.

[0033] In this embodiment, the connected domain pixel area threshold is set , the connected domain pixel area is smaller than The pseudo-connected domain formed by isolated noise points is removed by filtering out the regions.

[0034] Step S3: Based on the determined candidate jet stream connected domain, further extract the jet stream core parameters, including the jet stream axis height , Maximum wind speed , height of the upper boundary of the jet stream . The following steps are included: S31, according to Matrix, for each time point The vertical section of is used to detect the number of connected domains. Figure 2 The figure shows the horizontal wind speed profile at 3:00 obtained by vertical detection. It is detected that there are 2 connected domains in the vertical direction at this time, which are marked as the first connected domain and the second connected domain respectively.

[0035] S32, yes Figure 2 The first connected domain and the second connected domain are respectively tested for extreme values ​​to determine the first maximum wind speed point in each connected domain. and the second maximum wind speed point , define its height as the height of the first jet axis and the second jet stream axis high speed .like Figure 2 The maximum wind speed point in the first connected domain is marked with an asterisk, and the maximum wind speed point in the second connected domain is marked with a solid square point.

[0036] S33, at the height of the first jet axis and the second jet axis height Find the minimum wind speed between ,correspond Figure 2 The blue dotted line marks the height , is defined as the candidate first jet upper boundary height. and the upper search boundary Find the minimum wind speed between ,correspond Figure 2 The red dotted line marks the height , is determined as the candidate upper boundary height of the second jet.

[0037] Step S4: Based on the jet stream parameters initially extracted in step S3, the maximum wind speed difference at each time point in vertical height is calculated. With wind speed gradient , the calculation formula is as follows: ; ; In order to ensure the physical rationality of the rapids, this embodiment sets the wind speed difference threshold and wind speed gradient threshold , perform data screening: only keep the wind speed difference Greater than or equal to The jet layer and wind speed gradient Less than or equal to to ensure that the intensity of the jet stream meets the characteristic requirements.

[0038] like Figure 3 (b) and Figure 4 As shown in (b), the effective jet layers finally selected are marked with black dotted lines to indicate the jet axis height. Figure 3 (a) and Figure 4Compared with the traditional method shown in (a) in FIG, the embodiment of the present invention can not only accurately capture a single jet layer, but also accurately identify a double-layer low-altitude jet with complex stratification characteristics. In addition, for wind speed fluctuations caused by short-term gusts, the present invention effectively eliminates wind speed fluctuations caused by short-term gusts in the afternoon through time window screening and wind speed gradient filtering, thereby improving the accuracy and reliability of jet identification.

Claims

1. A double-layer jet stream identification method based on wind laser radar, characterized in that: The following steps are involved: (1) Obtain horizontal wind speed profile data from the wind laser radar within a preset time period; (2) Perform time-height two-dimensional connected domain detection on horizontal wind speed profile data to screen candidate jet stream connected domains; (3) Extract the core parameters of the jet stream, including the jet stream axis height, maximum wind speed, and jet stream upper boundary height; (4) Calculate the maximum wind speed difference and wind speed gradient at each time point, set the wind speed difference threshold and gradient threshold, and screen the effective jet layer; (5) Dynamically classify the jet stream intensity based on the maximum wind speed and wind speed difference of the effective jet layer.

2. A double-layer jet stream identification method based on wind laser radar according to claim 1, characterized in that: In step (2), the details are as follows: Set the altitude range for low-altitude jet stream identification and maximum wind speed threshold , traverse the time-height wind speed data, mark the pixels that meet the maximum wind speed threshold as candidate areas; scan the candidate areas point by point, based on the time window threshold and the height window threshold, allow the wind speed to be discontinuous in the window, and mark the same connected domain; filter out short-term disturbances and isolated noise through the time span threshold and the pixel area threshold, and obtain the final candidate jet connected domain.

3. The double-layer jet stream identification method based on wind laser radar according to claim 2 is characterized in that: In step (2), the time window threshold and the height window threshold allow the connected domain to be interrupted by no more than 3 consecutive time points in the time dimension and no more than 5 consecutive height layers in the height dimension, respectively.

4. The double-layer jet stream identification method based on wind laser radar according to claim 1 is characterized in that: In step (3), the number of connected domains of the vertical section at each time point is detected; the maximum wind speed point of each connected domain and the corresponding jet axis height are determined; the minimum wind speed value is found between the jet axis height and the search upper boundary, and the jet upper boundary height is determined.

5. The double-layer jet stream identification method based on wind laser radar according to claim 4 is characterized in that: In step (3), the maximum wind speed point of each connected domain is determined by the local extreme value detection algorithm, and the pseudo extreme values ​​caused by noise are eliminated.

6. The double-layer jet stream identification method based on wind laser radar according to claim 4 is characterized in that: In step (3), if there is only a single connected domain, then at the jet axis height to Find the minimum wind speed to determine the upper boundary height .

7. The double-layer jet stream identification method based on wind laser radar according to claim 1 is characterized in that: In step (4), calculate the maximum wind speed difference at each time point in vertical height With wind speed gradient , the calculation formula is as follows: ； ； in, is the maximum wind speed in the effective jet layer, is the corresponding height position; is the minimum wind speed above, is the corresponding height position.

8. The double-layer jet stream identification method based on wind laser radar according to claim 1 is characterized in that: In step (5), the dynamic classification type of rapids intensity is: Type 1: and It is a weak rapid; Type 2: and It is a moderate rapid; Type 3: and It is a strong rapids; Type 4: and It is a super rapid.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the computer program is loaded into a processor, a double-layer jet stream identification method based on wind laser radar according to any one of claims 1 to 8 is implemented.

10. A storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, a double-layer jet stream identification method based on wind laser radar according to any one of claims 1 to 8 is implemented.

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