A method for monitoring low-altitude atmospheric wind shear and turbulence based on wind profiler radar

Abstract

The present invention discloses a method for monitoring low-altitude atmospheric wind shear and turbulence based on a wind profiler radar. The radial velocity data in the five-beam detection mode are used to calculate the vertical wind speed and horizontal wind speed profiles, and the wind shear index in the vertical and horizontal directions is obtained accordingly; at the same time, the atmospheric horizontal motion uniformity index is calculated by four sets of horizontal wind speed standard deviations. Combining the radial velocity spectral width data with other observation methods such as microwave radiometers, soundings or temperature profiles provided by satellites, five sets of turbulent kinetic energy dissipation rate profiles are calculated and synthesized. This method can continuously monitor the wind shear, horizontal motion uniformity and turbulence conditions in the low-altitude atmosphere at high temporal and spatial resolution, providing strong technical support for low-altitude flight safety.

Description

Technical Field

[0001] The invention relates to a low-altitude atmospheric wind shear and turbulence monitoring method based on wind profile radar, and belongs to the field of atmospheric science. Background Art

[0002] Low-altitude economy refers to a comprehensive economic form with a vertical range of less than 1,000 meters, which can be extended to a low-altitude airspace of no more than 3,000 meters according to actual needs. It is mainly based on civil manned or unmanned aircraft, and is driven by low-altitude flight activities in multiple scenarios such as manned and cargo transportation. It radiates and drives the integrated development of related fields.

[0003] Meteorological service guarantee, as a part of the low-altitude economic service guarantee system, plays a very important role. It plays an important technical support role in planning airworthy airspace, designing safe and reasonable routes, and coordinating the formulation of low-altitude airspace flight plans. Under clear sky conditions, the atmospheric motion factors that affect flight safety mainly include wind shear and turbulence. Wind shear is divided into horizontal wind shear and vertical wind shear. Traditional methods are difficult to accurately obtain the movement of atmospheric motion in the horizontal and vertical directions at the same time. The inhomogeneity of atmospheric motion in the horizontal and vertical dimensions is an important factor affecting flight safety. Clear air turbulence is a very complex and common atmospheric motion phenomenon. Its strength and changing trend have a great impact on flight safety.

[0004] Since clear-sky atmospheric wind shear and turbulence pose a great threat to flight safety, some existing methods for calculating wind shear based on sounding are limited by the low density of the sounding station network. For example, in Jiangsu Province, there are only three sounding stations in the province, and there are only 2 to 3 soundings per day. The temporal and spatial resolution is low, which makes it difficult to meet the needs of users for high temporal and spatial resolution services. However, wind profiler radars have very high temporal and spatial resolutions, with a time resolution of generally 6 minutes and a vertical height resolution of 50m to 60m depending on the radar. The site density is also high. For example, in Jiangsu Province, 23 sites have been deployed and there will be more sites in the future. Therefore, the use of wind profiler radars can conduct all-weather continuous detection, and can observe the wind speed, wind direction, wind shear and turbulence above the station in real time. It is an important tool for monitoring atmospheric motion conditions under clear sky conditions, and helps to provide relevant departments with a more effective means of monitoring and early warning of low-altitude atmospheric conditions. Summary of the invention

[0005] The present invention aims at the shortcomings that the existing ground sounding station network is sparsely distributed and the temporal and spatial resolution of detecting the low-altitude atmosphere is low. A low-altitude atmospheric wind shear and turbulence monitoring method based on wind profiler radar is proposed to solve the problem of insufficient recognition and early warning capabilities of low-altitude atmospheric motion wind shear and turbulence in the absence of low-altitude atmospheric monitoring means.

[0006] In order to solve the above technical problems, the method of the present invention needs to use five-beam wind profile radar data. The specific technical solution of the present invention is as follows:

[0007] A method for monitoring low-altitude atmospheric wind shear and turbulence based on wind profiler radar comprises the following steps:

[0008] Step S1, based on the radial velocity data in the five-beam detection mode of the wind profiler radar, a vertical wind speed profile is obtained by a vertical detection beam, and according to the obtained vertical wind speed profile, a vertical wind shear index of the vertical wind speed in any given height interval in the vertical direction is calculated respectively;

[0009] Step S2, based on the radial velocity data detected by the five-beam wind profiler radar, four sets of horizontal wind speed profiles are calculated using the three-beam horizontal wind inversion theory, and the vertical wind shear index of the horizontal wind speed at any given height interval in the vertical direction is calculated according to the obtained horizontal wind speed profiles;

[0010] Step S3, using the four groups of horizontal wind speeds calculated in step S2, calculating the standard deviation of the four groups of horizontal wind speeds and the atmospheric horizontal motion uniformity index;

[0011] Step S4, based on the radial velocity spectrum width data of the five-beam detection, combined with the temperature profile observed by the microwave radiometer or satellite, five sets of turbulent kinetic energy dissipation rate profiles are calculated and corrected according to the distance and synthesized;

[0012] Step S5, in combination with step S1-step S4, in the continuous high spatiotemporal resolution real-time observation mode of the wind profiler radar, the vertical shear index of horizontal wind and vertical wind, the atmospheric horizontal dimension motion uniformity index and the continuous spatiotemporal variation trend of the atmospheric turbulent kinetic energy dissipation rate are obtained.

[0013] As a preferred embodiment of the present invention, the specific method of step S1 is:

[0014] The wind profile radar launches five beams in the five directions of southeast, northwest, and center in a predetermined order. Each beam detection is divided into 1~gatenum distance bins, where gatenum is the number of distance bins, the length of each distance bin is GL, and the angle between each beam and the vertical direction is , the five beam radial velocities detected by the wind profiler radar are defined as , then the radial velocity of each range bin in each beam is defined as , where i=L, N, W, E, S, representing the middle beam, north beam, west beam, east beam and south beam respectively, j=1, 2, 3...gatenum;

[0015] For medium beam, vertical velocity , for the other four beams, the vertical velocity , for any given height interval H1 and H2, the vertical shear index of vertical wind is defined as:

[0016] (1)

[0017] According to formula (1), five groups of vertical wind shear index profiles can be calculated.

[0018] As a preferred embodiment of the present invention, the specific method in step S2 is:

[0019] The three-beam horizontal wind inversion method is used, with the middle beam pointing to the zenith and the radial velocity equal to the vertical velocity, that is, The two tilted beams differ by 90° in azimuth and measure the radial velocity. According to formula (2) and formula (3), two horizontal wind components are derived from the combination of two tilt beams and the middle beam: , , calculate four sets of horizontal wind speeds , horizontal wind direction (i=1~4):

[0020] (2)

[0021] (3)

[0022] Similarly, the horizontal wind vertical shear index for any given height interval H1 and H2 is defined as:

[0023] (4)

[0024] According to formula (4), four sets of horizontal wind vertical wind shear index profiles are calculated.

[0025] As a preferred embodiment of the present invention, the specific method of step S3 is:

[0026] For each range library of the wind profiler radar, four horizontal wind speeds are calculated by step S2: (i=1~4),

[0027] The mean horizontal velocity of this group is:

[0028] (5)

[0029] Standard Deviation for:

[0030] (6)

[0031] Similarly, the atmospheric horizontal dimensional homogeneity index is defined as :

[0032] (7)

[0033] Where abs is the absolute value function, max is the maximum value function of the four horizontal velocities in the distance library, when the atmospheric horizontal dimension homogeneity index When it is 0, it indicates that the horizontal dimension of the atmosphere in the distance library is isotropic and the horizontal motion of the atmosphere is highly uniform. When it is greater than 0, it indicates that the horizontal motion of the atmosphere is inhomogeneous, and The larger it is, the more inhomogeneous the horizontal motion of the atmosphere is.

[0034] As a preferred embodiment of the present invention, the specific method of step S4 is: first obtain the atmospheric temperature profile, interpolate to the same height resolution as the wind profile radar, and obtain the temperature profile. , turbulence dissipation rate The calculation formula is as follows:

[0035] (8)

[0036] Where C is a constant, N is the Bouvet frequency, is the radial velocity spectrum width of the wind profiler radar radial observation. The Bouvet frequency calculation formula is as follows:

[0037] (9)

[0038] Where g is the acceleration due to gravity, is the potential temperature, is a constant, is the vertical temperature gradient, , and is the ground temperature and air pressure;

[0039] Five groups of turbulent kinetic energy dissipation rates were calculated using the radial velocity spectrum widths of the five beams detected by the wind profiler radar and combined with the temperature profile. Profile;

[0040] Five groups of turbulent kinetic energy dissipation rates were calculated After profiling, five groups of turbulent dissipation rates are synthesized.

[0041] As a preferred embodiment of the present invention, the specific method for synthesizing five groups of turbulence dissipation rates is as follows: in the same detection mode, for the nth distance library, the vertical beam detection Height , tilt beam detection Height , and correct the distance. Correct the tilt beam data to the vertical beam height interval. For the medium beam, the turbulent kinetic energy dissipation rate is expressed by height instead of distance bin number. , for other beams, the corrected turbulent kinetic energy dissipation rate is for:

[0042] (10)

[0043] in represents the interpolation of the tilted beam, and the interpolation standard is the vertical beam height interval. The final synthesized turbulent kinetic energy dissipation rate profile is:

[0044] (11)

[0045] Among them, i=L, W, E, S, N, std is the standard deviation, To find the average function, It needs to be less than 3 times the standard deviation of the data set, otherwise it will be eliminated as an outlier.

[0046] Beneficial effects:

[0047] The main advantages of the method for calculating the low-altitude atmosphere related index and turbulent kinetic energy dissipation rate of the present invention are as follows:

[0048] 1. The present invention uses wind profiler radar radial velocity data to detect data in real time, with high temporal and spatial resolution and accuracy, and can perform continuous observation for 24 hours without human supervision;

[0049] 2. The present invention divides low-altitude wind shear into horizontal and vertical dimensions for calculation, which can make up for the shortcomings of current three-dimensional wind shear observation and improve the refined monitoring of low-altitude wind shear;

[0050] 3. The present invention provides a uniformity index of low-altitude atmospheric motion in the horizontal dimension, which improves the monitoring capability of low-altitude atmospheric motion state;

[0051] 4. The present invention uses the radial velocity spectrum width to calculate the turbulent kinetic energy dissipation rate, and corrects and synthesizes the turbulent kinetic energy dissipation rate according to the distance. It can monitor the turbulent motion conditions of the low-altitude atmosphere and provide a means for low-altitude flight users to monitor atmospheric turbulence in real time. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a flow chart of the method for calculating the low-altitude atmosphere related index and turbulent kinetic energy dissipation rate of the present invention;

[0053] Figure 2 This is a schematic diagram of five-beam wind profile radar detection;

[0054] Figure 3 Flowchart for the synthesis of turbulent kinetic energy dissipation rate. DETAILED DESCRIPTION

[0055] The following will be combined with the attached Figure 1-3 The present invention is described in detail with specific embodiments.

[0056] Reference Figure 1 This embodiment discloses a method for monitoring low-altitude atmospheric wind shear and turbulence based on a wind profiler radar, which mainly includes the following steps:

[0057] Step S1: Based on the radial velocity data detected by the five-beam wind profiler radar, five sets of vertical wind speed profiles can be calculated. Based on the obtained vertical wind speed profiles, the vertical wind shear index of any given height interval in the vertical direction is calculated. The specific calculation process is as follows:

[0058] like Figure 1 As shown in the figure, the wind profile radar launches five beams in the five directions of southeast, northwest, and center in a predetermined order. Each beam detection is divided into 1~gatenum distance bins (gatenum is the number of distance bins), and the length of each distance bin is GL (GL is generally 50m~60m in low-mode detection). The angle between each beam and the vertical direction is , the five beam radial velocities detected by the wind profiler radar are defined as , then the radial velocity of each range bin in each beam is defined as , where i=L, N, W, E, S represent the middle beam, north beam, west beam, east beam and south beam respectively, and j=1, 2, 3...gatenum.

[0059] For medium beam, vertical velocity , for the other four beams, the vertical velocity , for any given height interval H1 and H2, the vertical shear index of vertical wind is defined as:

[0060] (1)

[0061] According to formula (1), five groups of vertical wind shear index profiles can be calculated.

[0062] Step S2: Based on the radial velocity data detected by the five-beam wind profiler radar, four sets of horizontal wind speed profiles can be calculated using the three-beam horizontal wind inversion theory. Based on the obtained horizontal wind speed profiles, the vertical wind shear index of any given height interval in the vertical direction is calculated. Specific calculation process:

[0063] When the three-beam horizontal wind inversion theory is used, the middle beam points to the zenith and the radial velocity is equal to the vertical velocity, that is, The two tilted beams (four groups, east and south beam, east and north beam, west and north beam, west and south beam) differ by 90° in azimuth and measure the radial velocity. According to formula (2) and formula (3), two horizontal wind components can be derived from the combination of two tilt beams and the middle beam: , , and then calculate four sets of horizontal wind speeds , horizontal wind direction (i=1~4):

[0064] , (2)

[0065] , (3)

[0066] Similarly, the horizontal wind vertical shear index for any given height interval H1 and H2 is defined as:

[0067] (4)

[0068] According to formula (4), four sets of horizontal wind vertical wind shear index profiles can be calculated.

[0069] Step S3: Using the four groups of horizontal wind speed profiles calculated in step S2, calculate the standard deviations of the four groups of horizontal wind speeds in each distance library, and on this basis define and calculate the atmospheric horizontal dimension homogeneity index to represent the inhomogeneity of atmospheric motion in the horizontal dimension within the detection range of the wind profile radar.

[0070] Specific calculation process:

[0071] For each range library of the wind profiler radar, four horizontal wind speeds are calculated by step S2: (i=1~4),

[0072] The mean horizontal velocity of this group is:

[0073] (5)

[0074] Standard Deviation for:

[0075] (6)

[0076] Similarly, the atmospheric horizontal dimensional homogeneity index is defined as :

[0077] (7)

[0078] Where abs is the absolute value function, and max is the maximum value function of the four horizontal velocities in the distance library. When it is 0, it indicates that the horizontal dimension of the atmosphere in the distance library is isotropic and the horizontal motion of the atmosphere is highly uniform. When it is greater than 0, it indicates that the horizontal motion of the atmosphere is inhomogeneous, and The larger it is, the more inhomogeneous the horizontal motion of the atmosphere is.

[0079] Step S4: Based on the radial velocity spectrum width data of the five-beam detection, combined with other means such as microwave radiometers, soundings (referring to the national meteorological station, the sounding balloons released at a fixed time every day to observe the atmospheric temperature, pressure, humidity and wind conditions, which can obtain the temperature, pressure, humidity and wind information of the atmosphere from the bottom to the top) or temperature profiles observed by satellites, five sets of turbulent kinetic energy dissipation rate profiles are calculated and corrected according to the distance and synthesized, which can characterize the strength of turbulent motion within the detection range of the wind profile radar. Specific calculation process:

[0080] First, the atmospheric temperature profile is obtained by other observation methods (microwave radiometer, sounding, or satellite, etc.), and then interpolated to the same height resolution as the wind profile radar to obtain the temperature profile. . Turbulence dissipation rate The calculation formula is as follows:

[0081] (8)

[0082] Where C is a constant, N is the Bouvet frequency, is the radial velocity spectrum width of the wind profiler radar radial observation. The Bouvet frequency calculation formula is as follows:

[0083] (9)

[0084] Where g is the acceleration due to gravity, is the potential temperature, is a constant, is the vertical temperature gradient, , and is the ground temperature and air pressure, which can be obtained from ground observations.

[0085] Therefore, using the radial velocity spectrum width of the five beams detected by the wind profiler radar and combining it with the temperature profile, five sets of turbulent kinetic energy dissipation rates can be calculated: outline.

[0086] Five groups of turbulent kinetic energy dissipation rates were calculated After the profile, the five groups of turbulence dissipation rates are synthesized. The characteristics of the wind profile radar detection mode need to be taken into account during the synthesis. Since the beam in the wind profile radar is detected vertically, the other four beams are observed at a certain zenith angle ( Generally, it is 14°~15°). In the same detection mode, for the nth range library, the vertical beam detection Height , tilt beam detection Height , when the detection distance is close, and The approximate equal error is small. When the detection distance is far, and The error increases, =15°, for example, the error at 2000m reaches 70m, which exceeds the size of a distance bin. At this time, it is necessary to make distance corrections when synthesizing the turbulent kinetic energy dissipation rate profile, and correct the tilt beam data to the case where the vertical beam height interval is used as the standard. For the medium beam, the turbulent kinetic energy dissipation rate is expressed by height instead of the distance bin number. , for other beams, the corrected turbulent kinetic energy dissipation rate is for:

[0087] (10)

[0088] in represents the interpolation of the tilted beam, and the interpolation standard is the vertical beam height interval. The final synthesized turbulent kinetic energy dissipation rate profile is:

[0089] (11)

[0090] Among them, i=L, W, E, S, N, std is the standard deviation, To find the average function, It needs to be less than 3 times the standard deviation of the data set, otherwise it will be eliminated as an outlier.

[0091] Step S5: Using the calculation results of steps S1 to S4, combined with the continuous high temporal and spatial resolution observations of the wind profiler radar, we can obtain the real-time and continuous wind shear conditions of low-altitude atmospheric motion in the horizontal and vertical dimensions, the uniformity of atmospheric motion at different heights within the detection range of the wind profiler radar, and the dissipation rate of atmospheric turbulence kinetic energy at different heights within the detection range of the wind profiler radar. The specific calculation process is:

[0092] Steps S1 to S4 obtain the vertical profiles of each index at each observation moment. When the wind profile radar operates continuously in real time, a continuous spatiotemporal variation trend of each index above the measuring station can be obtained. As the observation continues, new real-time data is continuously added to provide users with real-time and continuous wind shear index, atmospheric motion homogeneity index and turbulent kinetic energy dissipation rate.

[0093] The present invention is disclosed above with preferred embodiments, which are not intended to limit the present invention. Any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. A method for monitoring low-altitude atmospheric wind shear and turbulence based on wind profiler radar, characterized in that: The following steps are involved: Step S1, based on the radial velocity data in the five-beam detection mode of the wind profiler radar, the vertical wind speed profile is obtained by the vertical detection beam, and the vertical wind shear index of the vertical wind speed in any given height interval in the vertical direction is calculated according to the obtained vertical wind speed profile; the wind profiler radar launches five beams in the five directions of southeast, northwest, and center for detection in a predetermined order, and each beam detection is divided into 1~gatenum distance bins, gatenum is the number of distance bins, the length of each distance bin is GL, and the angle between each beam and the vertical direction is , the five beam radial velocities detected by the wind profiler radar are defined as , then the radial velocity of each range bin in each beam is defined as , where i=L, N, W, E, S, representing the middle beam, north beam, west beam, east beam and south beam respectively, j=1, 2, 3...gatenum; For medium beam, vertical velocity , for the other four beams, the vertical velocity , for any given height interval H1 and H2, the vertical shear index of vertical wind is defined as: （1） According to formula (1), five sets of vertical wind shear index profiles can be calculated; Step S2, based on the radial velocity data in the five-beam detection mode of the wind profiler radar, four sets of horizontal wind speed profiles are calculated using the three-beam horizontal wind inversion theory, and the vertical wind shear index of the horizontal wind speed in any given height interval in the vertical direction is calculated according to the obtained horizontal wind speed profiles; Step S3, using the four groups of horizontal wind speeds calculated in step S2, calculating the standard deviation of the four groups of horizontal wind speeds and the atmospheric horizontal motion uniformity index; Step S4: Based on the radial velocity data of the wind profiler radar in the five-beam detection mode, combined with the temperature profile of the microwave radiometer or satellite observation, five sets of turbulent kinetic energy dissipation rate profiles are calculated and corrected according to the distance and synthesized: first, the atmospheric temperature profile is obtained, interpolated to the same height resolution as the wind profiler radar, and the temperature profile is obtained. , turbulent dissipation rate The calculation formula is as follows: （8） Where C is a constant, N is the Bouvet frequency, is the radial velocity spectrum width of the wind profiler radar radial observation; The Bouvet frequency calculation formula is as follows: （9） Where g is the acceleration due to gravity, is the potential temperature, is a constant, is the vertical temperature gradient, , and is the ground temperature and air pressure; Five groups of turbulent kinetic energy dissipation rates were calculated using the radial velocity spectrum widths of the five beams detected by the wind profiler radar and combined with the temperature profile. Profile; Five groups of turbulent kinetic energy dissipation rates were calculated After the profile is drawn, the five groups of turbulence dissipation rates are synthesized; the specific method for synthesizing the five groups of turbulence dissipation rates is as follows: in the same detection mode, for the nth range library, the vertical beam detection Height , tilt beam detection Height , and correct the distance. Correct the tilt beam data to the vertical beam height interval. For the medium beam, the turbulent kinetic energy dissipation rate is expressed by height instead of distance bin number. , for other beams, the corrected turbulent kinetic energy dissipation rate is for: （10） in It represents the interpolation of the inclined beam, the interpolation standard is the vertical beam height interval, and the final synthesized turbulent kinetic energy dissipation rate profile is: （11） Among them, i=L, W, E, S, N, std is the standard deviation, To find the average function, It needs to be less than 3 times the standard deviation of the data set, otherwise it will be eliminated as an outlier; Step S5, in combination with step S1-step S4, in the continuous high spatiotemporal resolution real-time observation mode of the wind profiler radar, the vertical shear index of horizontal wind and vertical wind, the atmospheric horizontal dimension motion uniformity index and the continuous spatiotemporal variation trend of the atmospheric turbulent kinetic energy dissipation rate are obtained.

2. The method for monitoring low-altitude atmospheric wind shear and turbulence based on wind profiler radar according to claim 1, characterized in that: The specific method in step S2 is: The three-beam horizontal wind inversion method is used, with the middle beam pointing to the zenith and the radial velocity equal to the vertical velocity, that is, The two tilted beams differ by 90° in azimuth and measure the radial velocity. According to formula (2) and formula (3), two horizontal wind components are derived from the combination of two tilt beams and the middle beam: , , calculate four sets of horizontal wind speeds , horizontal wind direction : （2） （3） Similarly, the horizontal wind vertical shear index for any given height interval H1 and H2 is defined as: （4） According to formula (4), four sets of horizontal wind vertical wind shear index profiles are calculated.

3. The method for monitoring low-altitude atmospheric wind shear and turbulence based on wind profiler radar according to claim 1, characterized in that: The specific method of step S3 is: For each range library of the wind profiler radar, four horizontal wind speeds are calculated by step S2: , The mean horizontal velocity of this group is: （5） Standard Deviation for: （6） Defining the atmospheric horizontal dimensional homogeneity index : （7） Where abs is the absolute value function, max is the maximum value function of the four horizontal velocities in the distance library, when the atmospheric horizontal dimension homogeneity index When it is 0, it indicates that the horizontal dimension of the atmosphere in the distance library is isotropic and the horizontal motion of the atmosphere is highly uniform. When it is greater than 0, it indicates that the horizontal motion of the atmosphere is inhomogeneous, and The larger it is, the more inhomogeneous the horizontal motion of the atmosphere is.

Images