Dual-radar three-dimensional wind field inversion method considering standard atmospheric influence

Abstract

The invention discloses a dual-radar three-dimensional wind field inversion method considering standard atmospheric influence under an earth coordinate system, which comprises the following steps of: firstly, converting polar coordinates of radial observation of radars into latitude and longitude grid coordinates, and then converting an inversion grid target point from the latitude and longitude grid coordinates to the earth coordinate system; obtaining position coordinates of the inversion grid target point and the two radars in an earth coordinate system; and finally, performing double-radar wind field inversion considering the standard atmospheric influence under the earth coordinate system, considering the influence of the standard atmospheric influence on the inversion grid target point three-dimensional wind field on the radial speed projection in the inversion wind field iteration equation set, and meanwhile, considering the influence of the density change on the mass continuity equation under the standard atmospheric influence condition. Therefore, accurate calculation of double-radar three-dimensional wind field inversion is realized, and accurate and reliable three-dimensional wind field inversion information is obtained. Based on the method of the invention, accurate calculation of dual-radar three-dimensional wind field inversion can be realized, and accurate and reliable wind field information values can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of atmospheric remote sensing monitoring and analysis, and relates to a three-dimensional wind field inversion method of a dual Doppler weather radar, and specifically to a dual radar three-dimensional wind field inversion method considering the influence of a standard atmosphere in an earth coordinate system. Background Art

[0002] Three-dimensional wind field data are very important for disastrous weather monitoring, numerical forecasting and model verification, as well as mesoscale weather dynamics analysis. Radar, as an effective means of observation for mesoscale and small-scale weather monitoring, can obtain radial velocity information along the direction of the radar antenna. However, this velocity information lacks intuitiveness, and a single radar cannot reflect the true vector velocity of precipitation particles.

[0003] With the development and maturity of radar wind field inversion technology, the application of dual-radar wind field inversion is becoming more and more extensive. The radial velocities observed by two Doppler weather radars are synthesized, and the real three-dimensional wind field information of precipitation echoes can be inverted with the help of relevant assumptions and equations.

[0004] However, most algorithms are calculated in the Cartesian coordinate system, ignoring the influence of the earth's surface as a spherical surface, and not considering the accuracy of the position calculation of the long-distance radar beam. This has a great impact on the wind field inversion analysis of distant weather systems, and it is also difficult to realize the networking application of wind field inversion. In order to ensure the accuracy and applicability of wind field inversion, the patent "A method for three-dimensional wind field inversion of dual Doppler radars" uses a dynamic earth coordinate system and equal longitude and latitude and equal altitude grids for dual radar wind field inversion. This method not only realizes the accurate calculation of the influence of the earth's curved surface, but also facilitates the networking analysis of wind field products and comprehensive analysis with other products. In addition, since the atmosphere is not a uniform fluid, the electromagnetic waves emitted by the radar do not propagate in a straight line under different atmospheric density distributions, but propagate in a curve formed by multiple refractions. Therefore, when calculating the precise position of the radar storage point, it is necessary to consider the influence of its curved propagation, and it is necessary to consider the influence of standard atmospheric refraction on the projection of the inverted wind field in the direction of electromagnetic wave propagation in the dual radar inversion formula. The patent "A method for inverting three-dimensional wind fields using dual Doppler radars" only considers the change in the projection coefficient of the vertical velocity of the target point, but does not calculate the change in the projection coefficient of the horizontal velocity of the target point. In addition, there are some problems in the derivation formula of the projection coefficient of the vertical velocity, and the final calculation formula is quite complicated.

[0005] In addition, if the background of standard atmospheric influence conditions is taken into account, it is also necessary to calculate the approximate change of density with height in the continuity equation, so as to finally achieve the accurate calculation of radar three-dimensional wind field inversion and obtain accurate and reliable inverted wind field information values. However, previous inversion algorithms and the patent "A Dual Doppler Radar Three-Dimensional Wind Field Inversion Method" directly ignore the spatial changes of density. Summary of the invention

[0006] The present invention proposes a dual-radar three-dimensional wind field inversion method considering the influence of the standard atmosphere in the earth coordinate system. The method considers the influence of the earth's curved surface and the standard atmosphere, strictly derives the conversion formula from the polar coordinates of the radar radial observation to the longitude and latitude grid coordinates, and the conversion formula from the longitude and latitude grid coordinates to the earth coordinate system, and calculates the precise position of the two radar inversion grid target points. In addition, the influence of the atmospheric standard refraction on the three-dimensional wind field of the inversion grid target point on the radial velocity projection is considered in the calculation formula of the dual-radar wind field inversion, and the projection coefficient of the three-dimensional wind field of the inversion target point on the true radial velocity (tangential direction of the electromagnetic wave propagation curve) is derived; in addition, the influence of density change on the mass continuity equation under the influence of the standard atmosphere is considered, and the term of density change with height is added, so that the accurate calculation of the radar three-dimensional wind field inversion can be finally realized, and accurate and reliable wind field information values ​​can be obtained.

[0007] The technical solution adopted by the present invention is as follows:

[0008] First, the polar coordinates of the radar radial observation are converted to the latitude and longitude grid coordinates, which specifically includes the following steps:

[0009] 1) Read the longitude, latitude, altitude, and radial velocity information of the radar location from the radar base data. The radial velocity information includes: radial velocity value, azimuth, elevation, range library order, and range library resolution of the radial velocity. Similarly, read the reflectivity information. The reflectivity information includes reflectivity value, azimuth, elevation, range library order, and range library resolution of the reflectivity.

[0010] 2) Under the condition of considering the influence of the standard atmosphere, according to the radial velocity related information or reflectivity related information, the height H of the observation point from the ground can be obtained by using the altimetry formula (1):

[0011] (1)

[0012] Where h is the radar antenna height (i.e., the height of the radar location), δ is the elevation angle of the radial velocity or reflectivity, R is the slant range (obtained by multiplying the range library order Num of the radial velocity or reflectivity by the range library resolution dpl_reso), and H is the height of the radar beam center axis above the ground at the slant range R; R m is the equivalent radius of the Earth, which is the real radius of the Earth R m of times, about 8500km.

[0013] 3) Calculate the observation point P 1 Distance R from radar A on the ground CB , C and B are observation points P1 The projection of radar A on the earth:

[0014] (2)

[0015] in, for , using triangle AO The cosine theorem formula can be obtained, where O is the center of the earth.

[0016] 4) Now we know the longitude rlon and latitude rlat of point B, and the spherical distance from point C to point B , the azimuth Azim between point C and point B (the azimuth corresponding to the radial velocity or reflectivity), the latitude of point C can be obtained by using the spherical trigonometric cosine theorem and sine theorem in the spherical triangle formed by the North Pole N and points C and B and longitude This also gives the observation point P 1 Longitude ,latitude , height value +H.

[0017] 5) Using the longitude, latitude and altitude values ​​of the observation points, the volume scan data values ​​(including reflectivity and radial velocity) of all observation points are interpolated to the grid target points of equal longitude, latitude and altitude that need to be inverted. The Cressman distance weighted interpolation method is used in the horizontal direction, and linear interpolation is used in the vertical direction to obtain the reflectivity and radial velocity values ​​of the inversion grid target points.

[0018] Then, the inversion grid target points are converted from the latitude and longitude grid coordinates to the earth coordinate system to obtain the position coordinates of the inversion grid target points and the two radars in the earth coordinate system. The specific method is:

[0019] The origin of the earth coordinate system is set at the center of the earth, the z-axis points to the zenith through the inversion grid target point P, the x-axis points to the east of point P, and the y-axis points to the north of point P. The coordinate system is not fixed, it changes with the change of the inversion grid target point, so it is called a dynamic earth coordinate system.

[0020] In the latitude and longitude grid coordinates, the longitude lon, latitude lat, and height value H of the inversion grid target point P are known. Radar A 1 / A 2 Longitude rlon, latitude rlat, and altitude h.

[0021] Then in the Earth coordinate system, the coordinates of point P are P(0,0,R m +H).

[0022] According to the longitude, latitude, and altitude of the two radars under the longitude and latitude grid coordinates and the position coordinates of the inversion grid target point in the earth coordinate system, the position coordinates of the two radars in the earth coordinate system are calculated by the spherical trigonometric cosine theorem and the sine theorem respectively. The specific method is as follows:

[0023] Set the coordinates of point P to P(0,0,z), radar A 1 The coordinates of the point ( , , ) can be represented by the spherical triangle CNA 1 The spherical trigonometric cosine theorem and sine theorem are obtained, where N is the North Pole. Radar A 2 The coordinates of the point ( , , ) Similarly, the spherical triangle CNA 2 The spherical trigonometric cosine theorem and sine theorem are obtained. Substituting A for A 1 and A 2 , the spherical trigonometric cosine theorem and sine theorem of the spherical triangle CNA are shown in formulas (3)-(7).

[0024] + (3)

[0025] z 1 = (4)

[0026] (5)

[0027] x 1 = (6)

[0028] y 1 = (7)

[0029] in, , , They are respectively the radian corresponding to the arc length between points C and A on the sphere, the radian corresponding to the arc length between points N and A on the sphere, and the radian corresponding to the arc length between points N and C on the sphere.

[0030] Finally, the dual radar wind field inversion considering the influence of the standard atmosphere is performed in the earth coordinate system. The inversion wind field iteration equation group is constructed according to the reflectivity and radial velocity of the inversion grid target point; the influence of the standard atmosphere on the three-dimensional wind field of the inversion grid target point on the radial velocity projection is considered in the inversion wind field iteration equation group, and the projection coefficients of the vertical and horizontal velocities of the inversion grid target point in the radial velocity direction are derived; at the same time, the influence of density changes on the mass continuity equation under the influence of the standard atmosphere is considered, so as to realize the accurate calculation of the radar three-dimensional wind field inversion and obtain accurate and reliable three-dimensional wind field inversion information.

[0031] A 1 and A 2 are the locations of the two radars. From the above calculation, we can know that in the earth coordinate system, their coordinates are ( , , ),( , , ), the coordinates of point P are P(0,0,z), V r1 、V r2 are the radial velocities of the two radars at point P. Assuming that the three-dimensional velocity components at point P are u, v and w, the inversion wind field iterative equations are:

[0032] (8)

[0033] (9)

[0034] (10)

[0035] (11)

[0036] in, It is the terminal falling velocity of precipitation particles in the static atmosphere.

[0037] However, the above wind field iteration equation does not take into account the influence of the standard atmosphere, that is, it assumes that the electromagnetic wave propagates in a straight line and the direction of the radial velocity is the direction of the inversion grid target point pointing to the radar.

[0038] However, under the influence of atmospheric refraction, the electromagnetic wave is not propagated in a straight line, and the radial velocity direction of the inversion grid target point P is actually the tangent direction of the bending curve. Therefore, the projection of (u, v, w) in the radial velocity direction changes. It was previously projected in the straight line AP direction, but it should actually be projected in the tangent direction of the bending curve.

[0039] The calculation method of the projection coefficient of the vertical velocity w in the radial velocity direction is: ( ) instead of the original This item represents That's it, , now required Since the AP arc is the propagation path under the influence of the standard atmosphere, according to the standard atmospheric refraction parameter value table of Zhang Peichang et al. (2012), it can be known that the curvature of the propagation path is =4×10 -5 km -1 , n represents the refractive index of the standard atmospheric medium, h represents the height, and the whole term of dn to dh represents the change of the refractive index with height. From this, we can know the corresponding radius R of the propagation curve n is 25000km, in the isosceles triangle A It can be obtained in P ( ), we get The size of . Specifically, for point A 1 The radar at Point is the propagation curve path A 1 The center of P; in the isosceles triangle A 1 In P, we get A 1 P ; Line L 1 L 2 is the propagation curve path A 1 The tangent line of P can be obtained A 1 PL 1 ; In triangle A 1 In OP, we can get A 1 PO; according to A 1 PL 1 and A 1 PO, you can get L 1 PO, will L 1 PO is abbreviated as θ 1 , thus obtaining the projection coefficient cosθ of the vertical velocity w of the inversion grid target point on the radial velocity 1 ; Similarly, for point A 2 The projection coefficient cosθ of the vertical velocity w of the inversion grid target point P in the radial velocity direction can be calculated by using the radar at 2;

[0040] The calculation of the projection coefficients of the horizontal velocities u and v in the radial velocity direction is relatively complicated. Taking the v component as an example, the calculation process is described in detail.

[0041] For point A 1 If the influence of atmospheric refraction is not considered, the radar at the location is projected on the blue straight line. is the projection coefficient of this component. Now we need to project it onto the tangent line of the curved curve, through A 1 D is the intersection of the plane and PO. 1 There is point E in the due north direction and A 1 The length of E is y 1 , straight line L 1 L 2 The intersection point with the plane is point G, equal L 1 PO, the straight line passing through point G in the due north direction intersects with the straight line ED at point F. Let the coordinates of point G be ( , , ), then the current projection coefficient is . From similar triangle A 1 ED and triangle GFD give:

[0042] (12)

[0043] The same is true for the u component, and the projection coefficient is: (13)

[0044] Similarly, for point A 2 The radar at , we can get:

[0045] The projection coefficients of the horizontal velocities v and u of the inversion grid target point P on the radial velocity are: and .

[0046] Therefore, after considering the influence of the standard atmosphere, formulas (8)-(11) (i.e., the inverted wind field iterative equations) should be changed to:

[0047] (14)

[0048] (15)

[0049] in, and are the radial velocities of the two radars at the target points of the inversion grid after considering the influence of the standard atmosphere; is the final falling velocity of precipitation particles in the static atmosphere, which is estimated using the reflectivity I of the inversion grid target point:

[0050] (16)

[0051] In order to solve the inverted wind field iterative equations, the vertical velocity w needs to be calculated through the mass continuity equation:

[0052] (17)

[0053] And w satisfies:

[0054] (18)

[0055] Among them, z 0 Indicates the height of the next layer of grid points with the lowest valid interpolation point for the inversion grid target point.

[0056] Furthermore, the influence of density change on the mass continuity equation under standard atmospheric conditions is considered, specifically:

[0057] In the case of deep convection, the mass continuity equation can be approximated by the anelastic approximation (Ogura and Phyllips, 1962), ignoring the effects of density perturbations. , and based on the scale analysis, ignoring the density change in the horizontal direction, the mass continuity equation (17) is changed to:

[0058] (19)

[0059] Under standard atmospheric conditions, the density It changes with height, as shown in formula (20), which can be substituted into formula (19), that is, the standard atmosphere effect is also considered in the mass continuity equation.

[0060] (20)

[0061] Where Z is the height in meters; is the average sea level atmospheric density, about 1.2 kg / m 3 .

[0062] Thus, the accurate calculation of radar three-dimensional wind field inversion can be realized. The specific method is as follows: After the initial values ​​of u and v are given, the first estimated value of w can be obtained using the mass continuity equation (19). Then w is substituted into the inversion wind field iterative equation group (14) and (15) to recalculate u, v, and w. After several iterations, when the difference between the current and the next two inversion calculations is less than a given minimum value (such as 0.0001m / s), the three-dimensional wind field inversion results (u, v, w) that meet the accuracy requirements can be obtained.

[0063] The present invention also provides a dual-radar three-dimensional wind field inversion device taking into account the influence of standard atmosphere, the device comprising:

[0064] Coordinate conversion module 1 is used to interpolate the reflectivity and radial velocity of all observation points in the polar coordinates of the radar radial observation to the grid target points of equal longitude and latitude and equal altitude that need to be inverted, and obtain the reflectivity and radial velocity values ​​of the inverted grid target points in the longitude and latitude grid coordinates;

[0065] Coordinate conversion module 2 is used to convert the inversion grid target point from the latitude and longitude grid coordinates to the earth coordinate system, and obtain the position coordinates of the inversion grid target point and the two radars in the earth coordinate system;

[0066] The dual-radar wind field inversion module considering the influence of the standard atmosphere in the earth coordinate system is used to construct an inversion wind field iterative equation group according to the reflectivity and radial velocity of the inversion grid target point; in the inversion wind field iterative equation group, the influence of the standard atmosphere on the three-dimensional wind field of the inversion grid target point on the radial velocity projection is considered, and the projection coefficients of the vertical and horizontal velocities of the inversion grid target point in the radial velocity direction are derived; at the same time, the influence of density changes on the mass continuity equation under the influence of the standard atmosphere is considered, so as to realize the precise calculation of the radar three-dimensional wind field inversion and obtain accurate and reliable three-dimensional wind field inversion information.

[0067] The present invention also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the dual-radar three-dimensional wind field inversion method considering the influence of the standard atmosphere.

[0068] The present invention also provides a computer-readable storage medium on which computer instructions are stored, and the computer instructions are used to enable a computer to execute the dual-radar three-dimensional wind field inversion method considering the influence of the standard atmosphere.

[0069] The beneficial effects of the present invention are:

[0070] (1) The present invention takes into account the influence of the earth's curved surface and the standard atmosphere, and strictly derives the conversion formula from the polar coordinates of the radar radial observation to the longitude and latitude grid coordinates, and the conversion formula from the longitude and latitude grid coordinates to the earth coordinate system, which can accurately calculate the positions of the two radars and the inversion grid target points.

[0071] (2) The influence of atmospheric refraction is taken into account in the dual-radar wind field inversion equations, and the projection coefficient of the three-dimensional wind field of the inversion grid target point on the true radial velocity (tangential direction of the electromagnetic wave propagation curve) is derived, which can invert the three-dimensional wind field more accurately.

[0072] (3) In addition, by considering the influence of the standard atmosphere in the mass continuity equation and adding the term of density variation with height, the accurate calculation of the radar three-dimensional wind field inversion can be finally realized, and more accurate and reliable wind field information values ​​can be obtained.

[0073] (4) The inversion results of the method of the present invention were evaluated and tested on a long-term series using second-level sounding data, and it was found that the root mean square error was about 3.5 m / s. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 It is a schematic diagram for solving the height of the radar observation point under the equivalent earth radius;

[0075] Figure 2 It is a schematic diagram of the conversion of longitude and latitude grid coordinates to the earth coordinate system;

[0076] Figure 3 This is a schematic diagram of the dual radar wind field inversion without considering atmospheric refraction;

[0077] Figure 4 It is a schematic diagram of radar electromagnetic wave propagation considering the influence of standard atmosphere;

[0078] Figure 5 It is a schematic diagram of the radar radial velocity direction considering the influence of the standard atmosphere in the earth coordinate system. DETAILED DESCRIPTION

[0079] The scheme of the present invention is further explained below in conjunction with the accompanying drawings.

[0080] The embodiment of the present invention provides a dual-radar three-dimensional wind field inversion method considering the influence of standard atmosphere, which specifically includes the following steps:

[0081] First, the polar coordinates of radar radial observations are converted into longitude and latitude grid coordinates.

[0082] The longitude, latitude, altitude and radial velocity information of the radar location are read from the radar base data. The radial velocity information includes: radial velocity value, azimuth, elevation, distance library order and distance library resolution of the radial velocity. Similarly, the reflectivity information is read. The reflectivity information includes reflectivity value, azimuth, elevation, distance library order and distance library resolution of the reflectivity.

[0083] like Figure 1 As shown, O is the center of the earth, R m is the real radius of the Earth, A and P 1 are radar and observation point respectively, B and C are radar A and observation point P respectively 1 Projection on the Earth, O 1 is the center of the equivalent earth, C P1 is CP under the equivalent earth radius 1 The equivalent length of is the equivalent radius of the Earth.

[0084] Under the condition of considering the influence of the standard atmosphere, according to the information related to radial velocity or reflectivity, the height H of the observation point from the ground can be obtained by using the altimetry formula (1), that is, Figure 1 C P 1 length.

[0085] (1)

[0086] Where h is the radar antenna height (i.e., the height of the radar location), δ is the radial velocity or elevation angle of reflectivity, and R is the slant range (i.e., AP 1 The straight-line distance between two points is also called AP. 1 The straight-line distance between two points, i.e., the distance library order Num of the radial velocity or reflectivity multiplied by the distance library resolution dpl_reso), H is the height of the radar beam center axis from the ground at the slant range R, R m , is the real earth radius R m of times, about 8500km.

[0087] Then the observation point P can be calculated 1 Distance R from radar A on the ground CB :

[0088] (2)

[0089] in, for , using the triangle AOP 1 The cosine theorem formula can be obtained (where = +h; = +H).

[0090] (3)

[0091] Now we know the longitude rlon and latitude rlat of point B, and the spherical distance from point C to point B , the azimuth Azim between point C and point B (the azimuth corresponding to the radial velocity or reflectivity), the latitude of point C can be obtained by using the spherical trigonometric cosine theorem and sine theorem in the spherical triangle formed by the North Pole N and points C and B and longitude .

[0092] Spherical trigonometric cosine theorem:

[0093] + (4)

[0094] (5)

[0095] (6)

[0096] in, , , They are respectively the radian corresponding to the arc length between points N and C on the sphere, the radian corresponding to the arc length between points N and B on the sphere, and the radian corresponding to the arc length between points B and C on the sphere.

[0097] Spherical trigonometry sine theorem:

[0098] (7)

[0099] (8)

[0100] This also obtains the observation point Longitude ,latitude , height value +H.

[0101] Then, using the longitude, latitude, and altitude values ​​of the observation points, the volume scan data values ​​(reflectivity, radial velocity) of all observation points can be interpolated to the grid target points of equal longitude, latitude, and altitude that need to be inverted. The Cressman distance weighted interpolation method is used in the horizontal direction, and linear interpolation is used in the vertical direction, so as to obtain the reflectivity and radial velocity values ​​of the inversion target grid points under the longitude and latitude grid coordinates.

[0102] Then it is necessary to convert the inversion grid target points from the latitude and longitude grid coordinates to the earth coordinate system to obtain the coordinates of the inversion grid target points and the two radars in the earth coordinate system.

[0103] like Figure 2 As shown in the figure, the origin O of the earth coordinate system is set at the center of the earth, the z-axis points to the zenith through the inversion grid target point P, the x-axis points to the east of point P, and the y-axis points to the north of point P. The coordinate system is not fixed, it changes with the inversion target point, so it is called a dynamic earth coordinate system.

[0104] In the longitude and latitude grid coordinates, the longitude lon, latitude lat, and height value H of the grid target point P that needs to be inverted are known. Radar A 1 / A2 Longitude rlon, latitude rlat, and altitude h.

[0105] Then in the Earth coordinate system, the coordinates of point P are P(0,0,R m +H), set it to P(0,0,z), and A 1 The coordinates of the point ( , , ) can be represented by the spherical triangle CNA 1 The spherical trigonometric cosine theorem and sine theorem are obtained, where N is the North Pole. 2 The coordinates of the point ( , , ) Similarly, the spherical triangle CNA 2 The spherical trigonometric cosine theorem and sine theorem are obtained. Substituting A for A 1 and A 2 The spherical trigonometric cosine theorem and spherical trigonometric sine theorem of the spherical triangle CNA are specifically shown in formulas (9)-(15).

[0106] Spherical trigonometric cosine theorem:

[0107] NA (9)

[0108] Right now: (10)

[0109] (11)

[0110] in, , , They are respectively the arc length between points C and A on the sphere, the arc length between points N and A on the sphere, and the arc length between points N and C on the sphere.

[0111] Spherical trigonometry sine theorem:

[0112] (12)

[0113] Right now: (13)

[0114] x 1 = (14)

[0115] y 1 = (15)

[0116] Finally, the dual radar wind field inversion considering the influence of the standard atmosphere is performed in the earth coordinate system.

[0117] like Figure 3 As shown, A 1 and A 2 are the locations of the two radars. From the above calculation, we can know that in the earth coordinate system, their coordinates are ( , , ),( , , ), the coordinates of point P are P(0,0,z), V r1 、V r2 are the radial velocities of the two radars at point P. Assuming the three-dimensional velocity components of point P are u, v and w, the wind field iteration equations are:

[0118] (16)

[0119] (17)

[0120] (18)

[0121] (19)

[0122] in, It is the terminal falling velocity of precipitation particles in the static atmosphere.

[0123] The above wind field iteration equation does not take into account the influence of the standard atmosphere, such as Figure 3 The two blue lines shown indicate that the electromagnetic wave is assumed to propagate in a straight line, and the direction of the radial velocity is the direction from the inversion grid target point to the radar.

[0124] However, under the influence of the standard atmosphere, the electromagnetic wave propagation is not a straight line. The radial velocity direction of the inversion grid target point P is actually the tangential direction of the bending curve, that is, Figure 4 The gray straight line L 1 L 2 The tangential direction is shown. Figure 4 Use A instead of A 1 and A 2 , the calculation method of the projection coefficient of the vertical velocity of the inversion grid target point on the radial velocity is explained in detail. Therefore, the projection of (u, v, w) in the radial velocity direction changes. It was previously projected in the straight line AP direction, but it should actually be projected on the gray line L 1 L 2 Tangential direction.

[0125] The calculation method of the projection coefficient of the vertical velocity w in the radial velocity direction is:

[0126] use ( ) instead of the original This item represents That's it, , now required Since the AP arc is the propagation path under the influence of the standard atmosphere, according to the standard atmospheric refraction parameter value table of Zhang Peichang et al. (2012), it can be known that the curvature of the propagation path is =4×10 -5 km -1 , n represents the refractive index of the standard atmospheric medium, h represents the height, and the whole term dn to dh represents the change of the refractive index with height. From this, we can know the corresponding radius R of the propagation curve n is 25000km, in the isosceles triangle A It can be obtained in P ( ), we get The size of . value.

[0127] The calculation method of the projection coefficient of horizontal velocity u, v on radial velocity is:

[0128] Take the v component as an example, Figure 5 As shown, if the influence of atmospheric refraction is not considered, the projection is on the blue straight line. is the projection coefficient of this component. Now we need to project it onto the gray tangent line (i.e. the tangent line of the curved curve), and let the coordinates of point G be ( , , ), then the current projection coefficient is Point E is located at A 1 The due north direction and A 1 The length of E is y 1 , A 1 The ED plane is perpendicular to the Z axis, and point D is A 1 The intersection of ED plane and PO, point G is the intersection of the gray tangent line and A 1 The intersection of the ED plane, That is θ 1 , by similar triangle A 1 ED and triangle GFD give:

[0129] (20)

[0130] therefore: (twenty one)

[0131] (twenty two)

[0132] but: (twenty three)

[0133] Right now: (twenty four)

[0134] in, , , , , , The distance between point G and point F, point A 1 The distance between point E, the distance between point G and point D, and point A 1 The distance between point D, the distance between point D and point P, and the distance between point G and point P;

[0135] The same is true for the u component, and the projection coefficient is: (25)

[0136] Similarly, for point A 2 The radar at , we can get:

[0137] The projection coefficients of the horizontal velocities v and u of the inversion grid target point P on the radial velocity are: and .

[0138] Therefore, considering the influence of the standard atmosphere, formulas (16)-(19) can be changed to (26) and (27). Formulas (26) and (27) are the inversion wind field iterative equations considering the influence of the standard atmosphere:

[0139] (26)

[0140] (27)

[0141] in, and are the radial velocities of the two radars at the target points of the inversion grid after considering the influence of the standard atmosphere; is the final falling velocity of precipitation particles in the static atmosphere, which is estimated using the reflectivity I of the inversion grid target point:

[0142] (28)

[0143] To solve the inverted wind field iterative equations (26) and (27), the mass continuity equation is used to calculate the vertical velocity w:

[0144] (29)

[0145] And w must satisfy:

[0146] (30)

[0147] Among them, z 0 Indicates the height of the next layer of grid points with the lowest valid interpolation point for the inversion grid target point.

[0148] Considering the influence of density change on the mass continuity equation under standard atmospheric conditions, specifically:

[0149] In the case of deep convection, the mass continuity equation is approximated by the anelastic method (Ogura and Phyllips, 1962), neglecting the effects of density perturbations. , and based on the scale analysis, ignoring the density change in the horizontal direction, the mass continuity equation (29) is changed to:

[0150] (31)

[0151] In standard atmosphere, the density It changes with altitude. The specific calculation method is shown in formula (32), which can be substituted into formula (31) for calculation, that is, the influence of the standard atmosphere is also considered in the mass continuity equation.

[0152] (32)

[0153] Where Z is the height in meters. is the average sea level atmospheric density, about 1.2 kg / m 3 .

[0154] The precise calculation of radar three-dimensional wind field inversion is as follows: first, the initial values ​​of u and v are given, and the first estimated value of w can be obtained using the mass continuity equation (31). Then, w is substituted into the equations (26) and (27) to recalculate u, v, and w. After several iterations, when the difference between the current and the next two inversion calculations is less than the given minimum value of 0.0001 m / s, the three-dimensional wind field inversion results (u, v, w) that meet the accuracy requirements can be obtained.

[0155] In the dual-radar wind field inversion test, based on the above method, the long-term series evaluation and inspection were carried out using second-level sounding data. It was found that the root mean square error was about 3.5m / s, and the inversion result was relatively reliable.

[0156] Another embodiment of the present invention provides a dual-radar three-dimensional wind field inversion device considering the influence of standard atmosphere, the device comprising:

[0157] Coordinate conversion module 1 is used to interpolate the reflectivity and radial velocity of all observation points in the polar coordinates of the radar radial observation to the grid target points of equal longitude and latitude and equal altitude that need to be inverted, and obtain the reflectivity and radial velocity values ​​of the inverted grid target points in the longitude and latitude grid coordinates;

[0158] Coordinate conversion module 2 is used to convert the inversion grid target point from the latitude and longitude grid coordinates to the earth coordinate system, and obtain the position coordinates of the inversion grid target point and the two radars in the earth coordinate system;

[0159] The dual-radar wind field inversion module considering the influence of the standard atmosphere in the earth coordinate system is used to construct an inversion wind field iterative equation group according to the reflectivity and radial velocity of the inversion grid target point; in the inversion wind field iterative equation group, the influence of the standard atmosphere on the three-dimensional wind field of the inversion grid target point on the radial velocity projection is considered, and the projection coefficients of the vertical and horizontal velocities of the inversion grid target point in the radial velocity direction are derived; at the same time, the influence of density changes on the mass continuity equation under the influence of the standard atmosphere is considered, so as to realize the precise calculation of the radar three-dimensional wind field inversion and obtain accurate and reliable three-dimensional wind field inversion information.

[0160] Another embodiment of the present invention also provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the dual-radar three-dimensional wind field inversion method considering the influence of the standard atmosphere.

[0161] Another embodiment of the present invention further provides a computer-readable storage medium having computer instructions stored thereon, wherein the computer instructions are used to enable a computer to execute the dual-radar three-dimensional wind field inversion method considering the influence of the standard atmosphere.

Claims

1. A dual-radar three-dimensional wind field inversion method considering the influence of standard atmosphere, characterized in that: The following steps are involved: First, the polar coordinates of the radar radial observation are converted to the longitude and latitude grid coordinates: the reflectivity and radial velocity of all observation points in the polar coordinates of the radar radial observation are interpolated to the grid target points of equal longitude and latitude and equal altitude that need to be inverted, and the reflectivity and radial velocity values ​​of the inverted grid target points in the longitude and latitude grid coordinates are obtained; Next, the inversion grid target points are converted from the latitude and longitude grid coordinates to the earth coordinate system, and the position coordinates of the inversion grid target points and the two radars in the earth coordinate system are obtained; Finally, the dual radar wind field inversion considering the influence of the standard atmosphere is carried out in the earth coordinate system: the inversion wind field iterative equation group is constructed according to the reflectivity and radial velocity of the inversion grid target points; the influence of the standard atmosphere on the three-dimensional wind field of the inversion grid target points on the radial velocity projection is considered in the inversion wind field iterative equation group, and the projection coefficients of the vertical and horizontal velocities of the inversion grid target points in the radial velocity direction are derived; at the same time, the influence of density changes on the mass continuity equation under the influence of the standard atmosphere is considered, so as to realize the precise calculation of the radar three-dimensional wind field inversion and obtain accurate and reliable three-dimensional wind field inversion information.

2. The dual-radar three-dimensional wind field inversion method considering the influence of standard atmosphere according to claim 1 is characterized in that: The conversion of the polar coordinates of the radar radial observation to the latitude and longitude grid coordinates specifically includes the following steps: 1) Read the longitude, latitude, altitude, radial velocity and reflectivity information of the radar location from the radar base data; 2) Under the condition of considering the influence of standard atmosphere, the height of the observation point from the ground is calculated using the altimetry formula according to the radial velocity related information or reflectivity related information and the height of the radar location; 3) According to the trigonometric cosine theorem formula and the radius of the earth, the distance between the observation point and the radar station on the ground is calculated using the height of the observation point from the ground; 4) According to the spherical trigonometric cosine theorem and sine theorem, the longitude, latitude and altitude of the observation point are calculated using the distance between the observation point and the radar station on the ground, radial velocity related information or reflectivity related information, and the longitude and latitude of the radar location; 5) Using the longitude, latitude, and altitude values ​​of the observation points, the radial velocity and reflectivity of all observation points are interpolated to the grid target points of equal longitude, latitude, and altitude that need to be inverted. The Cressman distance weighted interpolation method is used in the horizontal direction, and linear interpolation is used in the vertical direction to obtain the reflectivity and radial velocity values ​​of the inversion grid target points.

3. The dual-radar three-dimensional wind field inversion method considering the influence of standard atmosphere according to claim 1 is characterized in that: The inversion grid target point is converted from the latitude and longitude grid coordinates to the earth coordinate system to obtain the position coordinates of the inversion grid target point and the two radars in the earth coordinate system. The specific method is: according to the longitude, latitude and altitude of the inversion grid target point in the latitude and longitude grid coordinates, the position coordinates of the inversion grid target point in the earth coordinate system are obtained; according to the longitude, latitude and altitude of the two radars in the latitude and longitude grid coordinates and the position coordinates of the inversion grid target point in the earth coordinate system, the position coordinates of the two radars in the earth coordinate system are respectively calculated by the spherical trigonometric cosine theorem and the sine theorem.

4. The dual-radar three-dimensional wind field inversion method considering the influence of standard atmosphere according to claim 1 is characterized in that: The derivation method of the projection coefficients of the vertical and horizontal velocities of the inversion grid target point in the radial velocity direction is specifically as follows: Known point A1( , , ), A2( , , ) are the position coordinates of the two radars in the earth coordinate system, point P(0,0,z) is the position coordinates of the inversion grid target point in the earth coordinate system, O is the center of the earth; the three-dimensional velocity components of point P are u, v, and w respectively; The calculation method of the projection coefficient of the vertical velocity w in the radial velocity direction is: For the radar at point A1, the projection coefficient of the vertical velocity w of the inversion grid target point P in the radial velocity direction is calculated as follows: the curvature of the electromagnetic wave propagation path is obtained according to the standard atmospheric refraction parameter table, and the corresponding radius of the electromagnetic wave propagation path is obtained according to the curvature of the electromagnetic wave propagation path; Point is the center of the propagation curve path A1P; in the isosceles triangle A1 In P, we get A1P ; Line L1L2 is the tangent of the propagation curve path A1P, so we can get A1PL1; In triangle A1OP, we can get A1PO; according to A1PL1 and A1PO, then we can get L1PO, L1PO is abbreviated as θ1, thus obtaining the projection coefficient cosθ1 of the vertical velocity w of the inversion grid target point on the radial velocity; Similarly, for the radar at point A2, the projection coefficient cosθ2 of the vertical velocity w of the inversion grid target point P in the radial velocity direction can be calculated; The calculation method of the projection coefficient of horizontal velocities u and v in the radial velocity direction is: For the radar at point A1, the projection coefficient of the horizontal velocity v of the inversion grid target point P on the radial velocity is calculated as follows: draw a plane perpendicular to PO through point A1, point D is the intersection of the plane and PO, there is point E in the due north direction of A1 and the length of A1E is y1, the intersection of the straight line L1L2 and the plane is point G, let the coordinates of point G be ( , , ), equal L1PO, the straight line from point G to the due north intersects the straight line ED at point F. From the similar triangles A1ED and GFD, we can get: ； therefore: ; ； but: ; Therefore, the projection coefficient of the horizontal velocity v of the inversion grid target point P on the radial velocity is: ； in, , , , , , They are the distance between point G and point F, the distance between point A1 and point E, the distance between point G and point D, the distance between point A1 and point D, the distance between point D and point P, and the distance between point G and point P; The horizontal velocity u is similar, and its projection coefficient on the radial velocity is: ； Similarly, for the radar at point A2, the projection coefficients of the horizontal velocities v and u of the inversion grid target point P on the radial velocity can be obtained: and ; After considering the influence of the standard atmosphere in the inversion wind field iteration equations, the inversion wind field iteration equations are specifically expressed as: ； ； in, and are the radial velocities of the two radars at the target points of the inversion grid after considering the influence of the standard atmosphere; is the final falling velocity of precipitation particles in the static atmosphere, which is estimated using the reflectivity I of the inversion grid target point: 。 5. The dual-radar three-dimensional wind field inversion method considering the influence of standard atmosphere according to claim 4 is characterized in that: The influence of density change on the mass continuity equation under standard atmospheric conditions is specifically: In the case of deep convection, the mass continuity equation is approximated by anelasticity, ignoring the effect of density perturbations. , and based on the scale analysis, ignoring the density change in the horizontal direction, the mass continuity equation is: ； Under standard atmospheric conditions, the density With the change of height, the specific calculation formula is: ； Where Z is the height in meters; is the mean sea level atmospheric density.

6. The dual-radar three-dimensional wind field inversion method considering the influence of standard atmosphere according to claim 5 is characterized in that: The specific method for realizing accurate calculation of radar three-dimensional wind field inversion is as follows: First, given the initial values ​​of u and v, the mass continuity equation is used to obtain the first estimated value of w, and w satisfies: ； Among them, z0 represents the height of the next layer of grid points of the lowest valid interpolation point of the inversion grid target point; Then, w is substituted into the inversion wind field iterative equation group to recalculate u, v, and w; After several iterations, when the difference between the data calculated by the current and the next inversion is less than a given value, a three-dimensional wind field inversion result (u, v, w) that satisfies the accuracy can be obtained.

7. A dual-radar three-dimensional wind field inversion device considering the influence of standard atmosphere, characterized in that: include: Coordinate conversion module 1 is used to interpolate the reflectivity and radial velocity of all observation points in the polar coordinates of the radar radial observation to the grid target points of equal longitude and latitude and equal altitude that need to be inverted, and obtain the reflectivity and radial velocity values ​​of the inverted grid target points in the longitude and latitude grid coordinates; Coordinate conversion module 2 is used to convert the inversion grid target point from the latitude and longitude grid coordinates to the earth coordinate system, and obtain the position coordinates of the inversion grid target point and the two radars in the earth coordinate system; The dual-radar wind field inversion module considering the influence of the standard atmosphere in the earth coordinate system is used to construct an inversion wind field iterative equation group according to the reflectivity and radial velocity of the inversion grid target point; in the inversion wind field iterative equation group, the influence of the standard atmosphere on the three-dimensional wind field of the inversion grid target point on the radial velocity projection is considered, and the projection coefficients of the vertical and horizontal velocities of the inversion grid target point in the radial velocity direction are derived; at the same time, the influence of density changes on the mass continuity equation under the influence of the standard atmosphere is considered, so as to realize the precise calculation of the radar three-dimensional wind field inversion and obtain accurate and reliable three-dimensional wind field inversion information.

8. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors implement the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having computer instructions stored thereon, characterized in that: The computer instructions are used to enable a computer to execute the steps of the method according to any one of claims 1 to 6.

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