A method for correcting a type of erroneous westerly trough line

Abstract

The present invention provides a method for correcting a type of erroneous westerly belt trough line, and belongs to the field of meteorological technology. The present invention determines the problem trough line and the truncation point, uses the truncation point to break the problem trough line into north and south trough lines, and corrects the north and south trough lines respectively to obtain a smooth curve. The present invention solves the problem of processing unreasonable trough line shapes in high-altitude weather maps and correctly expressing different types of weather conditions before and after the trough, laying a solid foundation for realizing precise and accurate automated analysis and forecasting and liberating forecasters.

Description

Technical Field

[0001] The invention belongs to the field of meteorological technology, and in particular relates to a method for correcting a type of erroneous westerly belt trough lines. Background Art

[0002] The atmosphere and water are both fluids, and their movements are very similar, with wave characteristics. In high-altitude weather maps, the peaks of atmospheric movement are called ridges, and the troughs are called troughs. Figure 1 As shown, because the fluctuations in the atmospheric westerly belt are close to a series of sine waves, and the troughs and ridges of multiple adjacent fluctuations are often connected in a linear shape, the troughs are also called trough lines. Figure 1 The mesowave line is the contour line of the potential height field and also the trace of the wind vector. Figure 1 In the figure, the solid black lines are contour lines of the potential height field, the dotted lines are ridge lines, the black lines are trough lines, and the arrows are the directions of the high-altitude airflow. Figure 2 As shown, the counterclockwise rotation of the atmosphere in the Northern Hemisphere is called a cyclone, and its curvature is positive; conversely, the curvature when rotating in a clockwise direction is negative, and is called an anticyclone.

[0003] According to meteorological principles, the cyclonic curvature of the contour lines of the potential height field at the trough line is the largest, and it is the line connecting the lowest potential height points in the neighborhood. The trough line is at the front edge of the movement of a group of high-altitude cold air, and reflects various meteorological characteristics such as the intensity of the cold air. The weather usually changes significantly near the trough line. For example, in the westerly belt of the northern hemisphere where most of my country is located, the front of the trough line is warm and humid southerly airflow with upward movement. The abundant water vapor often forms clouds and causes significant precipitation. The back of the trough line is dry and cold northerly wind with sinking movement, and the weather is often clear and cloudless. When the trough line passes through the westerly belt, the weather changes from cloudy and rainy to clear, so the trough line has a very important weather indication significance and is crucial to forecasting.

[0004] The trough line is complex in form and has a variety of shapes. It is not only closely related to the potential height field and wind field, but also has a complex dialectical relationship of unity of opposites with other types of weather systems under different atmospheric circulation situations. Therefore, in the high-altitude weather business analysis work, trough line analysis is the most difficult, reflecting the forecaster's theoretical literacy, forecasting experience and understanding of the circulation situation. Trough line analysis is the most critical high-altitude business analysis project in each forecast process, which is directly related to the success or failure of the forecast. Basic characteristics of trough lines:

[0005] 1) In the potential height field, the trough line is a narrow area extending westward and southward from the low value center, and the trough point is the relative southernmost end on the contour line.

[0006] 2) The airflow at the trough line is consistent with the contour lines of the potential height field and has positive curvature, which is a cyclonic flow field.

[0007] 3) The weather changes significantly near the trough line.

[0008] 4) There is a complex dialectical relationship of unity of opposites with other types of weather systems.

[0009] 5) A trough line corresponds to a mass of cold air.

[0010] In the westerly belt, the westerly trough extends southward from the low value center, indicating that the cold air moves from west to east (such as Figure 3 As shown, Figure 3 D in the middle is the low pressure center, and the shaded area A is the cold air mass). As the leading edge of the cold air activity, the trough lines are all convex toward the front of their movement, showing positive curvature.

[0011] Due to the high complexity of trough analysis, it is still difficult to use computers for automatic business analysis, so manual operations are still used in current meteorological business forecasts in various countries. In recent years, the automatic analysis of troughs has made significant progress, which has effectively promoted the automation of weather analysis and forecasting, and is expected to relieve the burden of manual labor of forecasters in the near future. However, due to the short history of this work and limited results, there are still many shortcomings. Among them, the description of the trough morphology still has errors under certain circumstances, and fails to correctly reflect the physical nature of the trough, thus affecting the forecast effect. Therefore, it is necessary to study and develop automated correction methods to further improve the automatic analysis technology of weather systems, promote the gradual realization of full automation of weather forecasting business, and completely liberate forecasters from routine manual labor. Summary of the invention

[0012] In view of the above-mentioned deficiencies in the prior art, the present invention provides a method for correcting a type of erroneous westerly belt trough lines, which solves the problem of handling unreasonable trough line shapes in high-altitude weather maps and correctly expressing different types of weather conditions before and after the trough, laying a solid foundation for realizing precise and accurate automated analysis and forecasting and for liberating forecasters.

[0013] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0014] This scheme provides a method for correcting a type of erroneous westerly trough line, including the following steps:

[0015] S1. Obtain wind field grid data, potential height field grid data and trough line data respectively, traverse each trough line data, calculate the curvature of each point on the trough line, and determine the problematic trough line using the curvature of each point;

[0016] S2. Find the minimum curvature point C of the problem slot line, set the data point of the minimum curvature point C in the problem slot line as the truncation point, and use the truncation point to divide the problem slot line into two sections, north and south;

[0017] S3, traverse the potential height field contour lines in the area where the problem trough line is located, find and analyze the closed potential height contour lines, and read the southernmost point S on the closed potential height contour line where the starting point ST of the problem trough line is located;

[0018] S4. According to the wind vector data, select the grid points adjacent to the southernmost point S, use the selected grid points to perform spatial interpolation of the user-defined function at the same latitude as the southernmost point, and find the position where the user-defined function approaches Δ1 according to the interpolation distribution of the user-defined function, move the southernmost point S westward to this position, and obtain the starting point S1 of the corrected trough line of the northern section, where Δ1 represents the value of the user-defined function R, and Δ1 = -0.8;

[0019] S5, using the selected grid points to perform spatial interpolation of the custom function at the same latitude as the cutoff point C, and finding the position where the custom function approaches Δ1 according to the interpolation distribution of the custom function, and moving the cutoff point C westward to the position to obtain the termination point Cn of the corrected trough line of the northern section;

[0020] S6, determine the midpoint Mn0 of the line connecting the starting point S1 of the corrected northern section trough line and the end point Cn of the corrected northern section trough line, move the center point Mn0 of the line eastward to obtain the vertex Mn of the convex front of the northern section trough line, and find the intersection point P of the convex front vertex Mn of the northern section trough line with the problem trough line at the same latitude, compare the intersection point P with the vertex Mn of the convex front of the northern section trough line, if the intersection point P is on the east side of the vertex Mn of the convex front of the northern section trough line, then replace the vertex Mn of the convex front of the northern section trough line with the intersection point P, otherwise, keep the vertex Mn of the convex front of the northern section trough line unchanged;

[0021] S7, taking the starting point S1 of the corrected trough line of the north section, the ending point Cn of the corrected trough line of the north section, and the vertex Mn of the convexity of the trough line of the north section as interpolation control points, performing interpolation processing to form a curve, and obtaining the correct trough line of the north section;

[0022] S8, move the end point Cn of the corrected trough line in the north section downward by Δ2 latitude to obtain the starting point Cs of the corrected trough line in the south section, move the midpoint Ms0 of the line connecting the starting point Cs of the corrected trough line in the south section and the end point E of the problem trough line eastward to obtain the vertex Ms of the convex front of the corrected trough line in the south section, and find the intersection point P of the convex front vertex Ms of the corrected trough line in the south section and the problem trough line, and compare the intersection point P with the vertex Ms of the convex front of the trough line in the south section. If the intersection point P is on the east side of the vertex Ms of the convex front of the trough line in the south section, replace the vertex Ms of the convex front of the trough line in the south section with the intersection point P, otherwise, keep the vertex Ms of the convex front of the trough line in the south section unchanged, wherein Δ2 represents the displacement degree of latitude, and Δ2=0.7;

[0023] S9, using the selected grid points to perform spatial interpolation of the custom function at the same latitude as the end point E of the problematic trough line, find the position where the custom function approaches Δ3 according to the interpolation distribution of the custom function, move the end point E of the problematic trough line westward to the position, and obtain the corrected trough line end point Es of the southern section, where Δ3 represents the value of the custom function R, and Δ3 = -0.1;

[0024] S10, taking the ending point E of the corrected trough line of the southern section, the vertex Ms of the convex front of the trough line of the southern section and the starting point Cs of the corrected trough line of the southern section as interpolation control points, performing interpolation processing to form a curve, and obtaining the correct trough line of the southern section.

[0025] Furthermore, the step S1 includes the following steps:

[0026] S101, respectively obtaining wind field grid data, geopotential height field grid data and trough line data;

[0027] S102, traverse the data of each slot line and calculate the curvature K of each point on the slot line:

[0028] S103, determine whether the curvature K of each point on the slot line is all positive. If so, the slot line is normal, check the next slot line, and return to step S102. Otherwise, the curvature K of a point on the slot line is negative, define the slot line as a problematic slot line, and enter step S2.

[0029] Furthermore, step S3 includes the following steps:

[0030] S301, traversing the potential height field contour lines in the area where the problem trough line is located, and obtaining all the closed contour lines of the potential height field;

[0031] S302, determine whether the starting point ST of the problematic trough line is within the closed contour area of ​​the potential height field. If so, take the southernmost point on the closed contour line of the potential height as S, and proceed to step S4. Otherwise, the closed contour line of the potential height field is not closed, and take the starting point ST of the problematic trough line as the southernmost point S, and proceed to step S4.

[0032] Furthermore, step S4 includes the following steps:

[0033] S401, customizing function R for each grid point according to wind vector data;

[0034] S402, determine whether the southernmost endpoint S is on a grid point, if so, take the four grid points of northwest, southwest, northeast and southeast adjacent to the southernmost endpoint S, and proceed to step S403, otherwise, take the four grid points of east, south, west and north adjacent to the southernmost endpoint S, and proceed to step S403;

[0035] S403, based on the four adjacent grid points, perform spatial interpolation on the user-defined function R at the same latitude as the southernmost endpoint S, and find the position where the user-defined function R approaches Δ1 based on the interpolation distribution of the user-defined function R, and move the southernmost endpoint S westward to the position to obtain the starting point of the corrected trough line of the northern section, and enter step S5.

[0036] Furthermore, the expression of the custom function in step S401 is as follows:

[0037]

[0038] Where R represents a custom function, and u and v are the wind speed values ​​in the x and y directions of each grid point, respectively.

[0039] The beneficial effects of the present invention are:

[0040] (1) Although significant progress has been made in the computer automatic analysis of trough lines, the description of trough line shapes still has errors under certain circumstances, and fails to correctly reflect the physical nature of the trough lines, thus affecting the forecast effect. It is necessary to study and develop an automated correction method to further improve the automatic analysis technology of weather systems. The present invention determines the problematic trough line and the cutoff point, uses the cutoff point to break the trough line into north and south sections, and corrects the north and south sections of the trough line respectively to obtain a smooth curve. The present invention solves the problem of handling unreasonable trough line shapes in high-altitude weather maps and correctly describing different types of weather conditions before and after the trough, laying a solid foundation for achieving precise and accurate automated analysis and forecasting and for liberating forecasters.

[0041] (2) The present invention divides the original problematic trough line into two sections, north and south, which conforms to the physical phenomenon of two groups of cold air. The separation at the minimum curvature point conforms to the requirements of the physical principle effect, and prepares for the following modification of the north-south trough line. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the fluctuations and trough ridge lines of the high-altitude westerly belt in the background technology.

[0043] Figure 2 It is a schematic diagram of cyclonic and anticyclonic curvature in background technology.

[0044] Figure 3 This is a schematic diagram showing the correct shape of the slot line in this example.

[0045] Figure 4 This is a schematic diagram of the incorrect shape of the slot line in this embodiment.

[0046] Figure 5 This is a schematic diagram of the correct groove line after correction in this embodiment.

[0047] Figure 6This is a schematic diagram of the key points for correcting the northern section of the problematic trough line in this embodiment.

[0048] Figure 7 This is a schematic diagram of the correction of the southern section of the problematic trough line in this embodiment.

[0049] Figure 8 The figure is a flow chart of the method of the present invention.

[0050] Fig. 9 In this embodiment, uv is Schematic diagram of the components in the xy direction.

[0051] Fig.10 This is a schematic diagram of curvature calculation in this embodiment.

[0052] Fig.11 Schematic diagram of the cutoff point C in this embodiment.

[0053] Fig.12 Schematic diagram of the non-closed contour line L1 and the closed contour line L0 in this embodiment.

[0054] Fig.13 This is a schematic diagram of the problem that the starting point of the slot line in this embodiment is within the nested closed contour line.

[0055] Fig.14 This is a schematic diagram of a non-closed contour line where the starting point of the problematic slot line in this embodiment is located.

[0056] Fig.15 Schematic diagram of the value of the V component in the westerly belt in this embodiment.

[0057] Fig.16 Schematic diagram of the inverse distance weighted method in this embodiment.

[0058] Fig.17 Schematic diagram of the position of adjacent grid points and S in this embodiment.

[0059] Fig.18 Schematic diagram of the overlap of the positions of adjacent grid points B and S in this embodiment.

[0060] Fig.19 It is a schematic diagram that point S is located on line segment BD in this embodiment.

[0061] Fig. 20 This is a schematic diagram of the correction of the cutoff point C in this embodiment.

[0062] Fig.21 Schematic diagram of the revision of the midpoint in this embodiment.

[0063] Fig. 22 This is a schematic diagram comparing Mn in this embodiment with the intersection point P of the original problem trough line at the same latitude.

[0064] Fig.23This is a revised schematic diagram of point E at the end of the problematic slot line in this embodiment.

[0065] Fig.24 This is a schematic diagram of the trough line before the 500hPa correction at 8:00 am on September 9, 2020 in this embodiment (the map in the figure is a map of a local area of ​​my country).

[0066] Fig.25 This is a schematic diagram of the trough line after correction at 500 hPa at 8:00 a.m. on September 9, 2020 in this embodiment (the map in the figure is a map of a local area of ​​my country). DETAILED DESCRIPTION

[0067] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0068] Example 1

[0069] Before explaining the present invention, the data format problem needs to be explained: MICAPS (Meteorological Information Comprehensive Analysis and Process System) is a comprehensive analysis and processing system for meteorological information in my country. It is matched with satellite communications and meteorological databases and is a human-computer interactive work platform for weather forecasts used in many industries across the country. MICAPS supports multiple data formats, among which the 14th type of data is the data of the final business product after manual modification. The present invention uses this type of data as the revised data format; the 4th type of data is grid data, which is used for various grid data; the 11th type of data is grid wind vector data, and the wind vector data required by the present invention is stored in this type of data format.

[0070] The trough line is an important representation of high-altitude cold air. It is not difficult to understand that cold air, as a dense substance with a higher density, will diffuse from its center to the warm air with a lower density under natural conditions, and the edge area will be deformed and weakened by contact with the relatively warm air around it; therefore, the cold air in the center is stronger, and the leading edge of the cold air, i.e., the trough line, will protrude toward the low-density warm air, which is consistent with the edge shape of water droplets and glue diffusing outward on a plane. Therefore, in the vast area of ​​the mid- and high-latitude westerly belt, the trough line appears to protrude toward the front of the movement, i.e., the east side, and has a convex shape, i.e., an arc with positive curvature, such as Figure 3 Each groove line should protrude in the running direction, showing a convex curve. However, inexperienced people sometimes describe the groove line as a wrong backward protrusion shape, such as Figure 4As shown, Figure 4 In the figure, the trough line in the box is not protruding forward, which is the wrong area. D is the low pressure center, and the shaded area is the cold air mass. The same is true for the following figures. This situation also exists in the computer automatic analysis process. Obviously, this violates the above characteristics and basic principles, and will cause misjudgment of whether a certain place is in the bad weather area before the trough or the sunny weather area after the trough, thus causing forecast errors. Therefore, in order to ensure the accuracy of the forecast, this type of erroneous trough line must be corrected. Figure 5 As shown, Figure 5 To correct the groove line after correction, Figure 5 In the figure, D is the low pressure center and the shaded area L is the cold air mass.

[0071] In view of the above situation, this error can be analyzed by the following principles.

[0072] It is known that the running speed C of the slot line is determined by the Rossby slot line equation:

[0073]

[0074] in: is the speed of the basic airflow, that is, the westerly wind speed at the location of the trough. The larger it is, the faster the trough moves. β = 2Ωcosψ / R, is the term for the Coriolis force (Coriolis force) changing with latitude, where Ω is the angular velocity of the earth's rotation, ψ is the latitude, and RR is the radius of the earth. The higher the latitude ψ, the faster the trough moves. L is the wavelength of the trough's fluctuations. The longer the wavelength, the slower the trough's running speed. Therefore, it can be seen that the shape of the trough is not only related to the aforementioned theoretical analysis, but also to its running speed, that is, the three influencing factors of equation (1). The trough is located at different latitudes, and its fluctuation wavelength and wind speed are different. Under specific parameter configuration conditions, there will be Figure 2 This situation.

[0075] By analyzing this situation, we can find that the reason is that due to the combined influence of the above three factors, some cold air moves slowly at a certain latitude due to weak westerly winds, and the cold air moves faster in the jet stream at other latitudes, that is, the north and south sections of the same group of cold air move at different speeds, and eventually separate into two groups of cold air, resulting in the reverse bending of the trough line in some areas. So the key is: this is not one group but two groups of cold air, so it cannot be expressed as a trough line. Since each group of cold air protrudes in front of its movement, the area concave to the back is not a significant cold air area, but the middle area between the two groups of cold air. From the order of inputting data from north to south, the curvature of the corresponding trough line of the protruding area in the front is positive, and the curvature of the problematic trough line at the separation point of the two groups of cold air should be negative. This incorrect expression of the trough line shape conflicts with the theory and violates the weather analysis business specifications, which will cause large errors in the analysis of the weather system in the involved areas, thereby affecting the forecast results. In order to comply with business specifications, correctly reflect meteorological principles, and ensure forecast quality, trough line correction must be carried out.

[0076] If we distinguish different cold air based on their physical nature, we can analyze two separate trough lines that conform to scientific principles and business specifications, thus solving this problem.

[0077] like Figure 6 As shown, Figure 6 In the figure, the black line is the original problematic trough line, and the gray line is the corrected trough line. Generally speaking, the two ends of the trough line are moved back to the west, and the middle is moved forward to the east to form a convex front. In the figure, S1 is the point after the correction of the westward movement, C is the cutoff point, Cn is the point after the correction of C westward movement, Mn0 is the midpoint of S1 and Cn, Mn is the intersection point Pn with the problematic trough line at the same latitude, and Mn is the position of Mn0 after the correction of the eastward movement. The modification effect of the northern section trough line is shown in the figure. Figure 6 As shown, Figure 6 In the figure, Cs is the starting point of the southern trough after the correction of Cn's southward movement, Ms0 is the midpoint of Cs and Es, Ms is the point after the correction of Ms0's eastward movement, Ms is the intersection point Ps with the problematic trough at the same latitude, E is the end point of the problematic trough, and Es is the end point of the southern trough after the correction of E's westward movement. The modification of the southern trough is similar, such as Figure 7 As shown, Figure 7 Corrected schematic diagram for the southern section of the problematic trough line. Figure 7 Cs is the point after Cn moves south, Ms0 is the midpoint of Cs and Es, Ms is Ms0 after moving east, Ms is the intersection point P with the problem trough line at the same latitude, E is the end point of the problem trough line, and Es is the point after E moves west.

[0078] The general idea of ​​the present invention is as follows:

[0079] 1. Find the point C with the minimum curvature in the problematic trough line, which is the boundary point between the two cold air masses. From this point, the problematic trough line with the original incorrect statement is divided into two sections, north and south.

[0080] 2. From the coordinate position of the starting point ST of the problem trough line, read the contour line data of the corresponding area, and find the southernmost point S on the closed contour line where ST is located. If there is no closed contour line, directly set ST as the starting point S of the northern section of the trough line. Take C as the end point of the northern section of the trough line. Move the starting point S and the end point C of the northern section of the trough line to the west for a distance to the new position, and obtain S1 and Cn, and move the midpoint Mn0 of this section of the trough line east to Mn, and compare Mn with the intersection point P of the problem trough line at the same latitude. If point P is on the east side of Mn, replace point Mn, otherwise it remains unchanged. The shape with the two ends facing backward and the middle facing forward makes this section of the trough line form a convex shape.

[0081] 3. Move the starting point S1 of the northern section of the trough line southward to Cs and set it as the starting point of the southern section of the trough line. Move the midpoint Mn0 of the southern section of the trough line eastward to Ms, and compare the intersection point P of Ms with the problem trough line at the same latitude. If point P is on the east side of Ms, replace point Ms, otherwise it remains unchanged, and move the end point E of the problem trough line westward to Es to make this section of the trough line form a convex shape.

[0082] 4. Use S1, Mn, Cn and Cs, Ms, Es as interpolation control points respectively, use the third-order Bessel function to interpolate to obtain a smooth and continuous curve, form two sections of slot lines, and complete the correction of the slot line.

[0083] Specifically, Figure 8 As shown, the present invention provides a method for correcting a type of erroneous westerly belt trough line, and the implementation method is as follows:

[0084] S1. Obtain wind field grid data, potential height field grid data and trough line data respectively, traverse each trough line data, calculate the curvature of each point on the trough line, and use the curvature of each point to determine the problematic trough line. The implementation method is as follows:

[0085] S101, respectively obtaining wind field grid data, geopotential height field grid data and trough line data;

[0086] S102, traverse the data of each slot line and calculate the curvature K of each point on the slot line:

[0087] S103, determine whether the curvature K of each point on the slot line is all positive, if so, the slot line is normal, check the next slot line, and return to step S102, otherwise, the curvature K of a point on the slot line is negative, define the slot line as a problematic slot line, and go to step S2;

[0088] S2. Find the minimum curvature point C of the problem slot line, set the data point of the minimum curvature point C in the problem slot line as the truncation point, and use the truncation point to divide the problem slot line into two sections, north and south;

[0089] S3, traverse the potential height field contour lines in the area where the problem trough line is located, find and analyze the closed potential height contour lines, and read the southernmost point S on the closed potential height contour line where the starting point ST of the problem trough line is located. The implementation method is as follows:

[0090] S301, traversing the potential height field contour lines in the area where the problem trough line is located, and obtaining all the closed contour lines of the potential height field;

[0091] S302, determine whether the starting point ST of the problematic trough line is within the closed contour area of ​​the potential height field, if so, take the southernmost point on the closed contour line of the potential height as S, and proceed to step S4, otherwise, the closed contour line of the potential height field is not closed, and take the starting point ST of the problematic trough line as the southernmost point S, and proceed to step S4;

[0092] S4. According to the wind vector data, the grid points adjacent to the southernmost endpoint S are selected, and the selected grid points are used to perform spatial interpolation of the user-defined function at the same latitude as the southernmost endpoint. According to the interpolation distribution of the user-defined function, the position where the user-defined function approaches Δ1 is found, and the southernmost endpoint S is moved westward to the position to obtain the starting point S1 of the corrected trough line of the northern section, where Δ1 represents the value of the user-defined function R, and Δ1 = -0.8. The implementation method is as follows:

[0093] S401, customizing function R for each grid point according to wind vector data;

[0094]

[0095] Where R represents a custom function, u and v are the wind speed values ​​in the x and y directions of each grid point respectively;

[0096] S402, determine whether the southernmost endpoint S is on a grid point, if so, take the four grid points of northwest, southwest, northeast and southeast adjacent to the southernmost endpoint S, and proceed to step S403, otherwise, take the four grid points of east, south, west and north adjacent to the southernmost endpoint S, and proceed to step S403;

[0097] S403, based on the four adjacent grid points, perform spatial interpolation on the user-defined function R at the same latitude as the southernmost endpoint S, and find the position where the user-defined function R approaches Δ1 based on the interpolation distribution of the user-defined function R, and move the southernmost endpoint S westward to the position to obtain the starting point of the corrected trough line of the northern section, and proceed to step S5;

[0098] S5, using the selected grid points to perform spatial interpolation of the custom function at the same latitude as the cutoff point C, and finding the position where the custom function approaches Δ1 according to the interpolation distribution of the custom function, and moving the cutoff point C westward to the position to obtain the termination point Cn of the corrected trough line of the northern section;

[0099] S6, determine the midpoint Mn0 of the line connecting the starting point S1 of the corrected northern section trough line and the end point Cn of the corrected northern section trough line, move the center point Mn0 of the line eastward to obtain the vertex Mn of the convex front of the northern section trough line, and find the intersection point P of the convex front vertex Mn of the northern section trough line with the problem trough line at the same latitude, compare the intersection point P with the vertex Mn of the convex front of the northern section trough line, if the intersection point P is on the east side of the vertex Mn of the convex front of the northern section trough line, then replace the vertex Mn of the convex front of the northern section trough line with the intersection point P, otherwise, keep the vertex Mn of the convex front of the northern section trough line unchanged;

[0100] S7, taking the starting point S1 of the corrected trough line of the north section, the ending point Cn of the corrected trough line of the north section, and the vertex Mn of the convexity of the trough line of the north section as interpolation control points, performing interpolation processing to form a curve, and obtaining the correct trough line of the north section;

[0101] S8, move the end point Cn of the corrected trough line in the north section downward by Δ2 latitude to obtain the starting point Cs of the corrected trough line in the south section, move the midpoint Ms0 of the line connecting the starting point Cs of the corrected trough line in the south section and the end point E of the problem trough line eastward to obtain the vertex Ms of the convex front of the corrected trough line in the south section, and find the intersection point P of the convex front vertex Ms of the corrected trough line in the south section and the problem trough line, and compare the intersection point P with the vertex Ms of the convex front of the trough line in the south section. If the intersection point P is on the east side of the vertex Ms of the convex front of the trough line in the south section, replace the vertex Ms of the convex front of the trough line in the south section with the intersection point P, otherwise, keep the vertex Ms of the convex front of the trough line in the south section unchanged, wherein Δ2 represents the displacement degree of latitude, and Δ2=0.7;

[0102] S9, using the selected grid points to perform spatial interpolation of the custom function at the same latitude as the end point E of the problematic trough line, find the position where the custom function approaches Δ3 according to the interpolation distribution of the custom function, move the end point E of the problematic trough line westward to the position, and obtain the corrected trough line end point Es of the southern section, where Δ3 represents the value of the custom function R, and Δ3 = -0.1;

[0103] S10, taking the ending point E of the corrected trough line of the southern section, the vertex Ms of the convex front of the trough line of the southern section and the starting point Cs of the corrected trough line of the southern section as interpolation control points, performing interpolation processing to form a curve, and obtaining the correct trough line of the southern section.

[0104] In this embodiment, the grid data is read. In order to find the unreasonable trough line, that is, to determine the problem trough line, it is necessary to read the potential height grid data, wind field grid data and trough line data. Fig. 9 As shown, the wind on the isobaric surface It is a two-dimensional vector. The grid data stored in the x and y directions are expressed as u wind in the east-west direction and v wind in the north-south direction (scalar). The potential height contour lines are generated from the potential height field data.

[0105] In this embodiment, the points on the slot line are traversed to determine the truncation point C. The data of each point on the slot line are traversed to calculate the curvature value of the slot line. If the curvature of a certain point is negative, it means that the slot line is incorrectly described and the problematic slot line must be corrected. Because the problematic slot line is a concave curve, it can be seen from the above characteristics analysis that it violates the diffusion effect in physics. The slot line is the edge in front of the cold air, and by the same token it should also protrude forward. The truncation point is the point with the minimum curvature in the slot line. Use P0, P1, and P2, a total of 3 points on the quadratic curve, to determine the curvature of the curve at point P1, such as Fig.10 As shown. The curvature is calculated once for every three points. Except for the starting point and the end point of the groove line, the curvature values ​​of the remaining points can be obtained, and the maximum value is found among them. First, it is expressed as a set of parametric equations (2).

[0106]

[0107] There are 6 unknown numbers and 6 known components in three points. Make 6 equations and solve a1, a2, a3, b1, b2, b3.

[0108] Calculate the curvature of each point on the problem slot line in the above way, find the point with the minimum curvature, and take it as the truncation point C of the problem slot line, such as Fig.11 As shown, Fig.11 The data on the right side of each point are the curvature values, and point C is the extreme value of negative curvature.

[0109] In this embodiment, the contour lines are divided into two categories: closed contour lines and non-closed contour lines. Therefore, to locate the problem slot line area, it is necessary to first determine whether there is a closed contour line, and the characteristic of a closed contour line is that the head and the tail can be connected. All the contour lines are traversed to obtain all the closed contour lines, and the coloring algorithm is used to determine whether the starting point of the problem slot line is within the closed contour line area, and then determine the required closed contour line of the problem slot line.

[0110] In this embodiment, Fig.12 As shown, Fig.12 ST is the starting point of the problem slot line. If the contour line L0 is closed, then any point P(x,y) on it is both the starting point and the end point. If a point in the contour line is randomly selected, it coincides with the last point in the order of this contour line. If P1(x1,y1) is taken as the first point of the contour line L0, and the number of points on the contour line is n, then the last point is Pn(x n ,y n ). On this closed contour line, the following relationship must be satisfied: (x1, y1) = (x n ,y n ), which can determine whether the contour line is closed. If the above conditions are not met, it is an open contour line. Fig.12 L1 in . Traverse all contour lines and distinguish between closed and non-closed contour lines.

[0111] In this embodiment, it is determined whether the starting point of the problematic slot line is within the closed contour line. If the starting point of the problematic slot line is within the area of ​​a closed contour line L0 and is the only closed contour line, then L0 is the closed contour line where the starting point of the problematic slot line is located. A coloring algorithm is used to determine whether the starting point of the problematic slot line is within the closed contour line L0. The coloring algorithm is a very basic and mature algorithm in computer graphics and will not be described further.

[0112] In this embodiment, the problem trough line is shown as 13. In this case, L0, L1, L2, and L34 all meet the condition of whether the starting point of the problem trough line is within the closed contour line. Since the starting point of the problem trough line is in the low-pressure center, it is only necessary to read the closed contour line L0 of the lowest potential height, which is the corresponding low-vortex center area, that is, the starting point area of ​​the trough line. Then select the southernmost point S in the closed contour line of the problem trough line, correct the S point to obtain the interpolation control point S1 as the starting point of the corrected trough line. Fig.14 As shown in FIG. 1 , if the starting point of the problematic slot line is not within the closed contour line, ST is the starting point of the problematic slot line, and the starting point of the problematic slot line is taken as S for revision.

[0113] In this embodiment, the interpolation control point is obtained by interpolating the westward movement according to the wind vector data using the inverse distance weighted method. When the starting point of the problem trough line is within the closed contour line, according to the characteristics of the trough line, its starting point should be located near the southernmost position of the minimum contour line of the potential height field in the area. The trough line is also the line connecting the maximum points of cyclonic shear in the wind field. The wind direction and wind speed on both sides have obvious changes. The two-dimensional wind vector is determined by the two components of the east-west wind u and the north-south wind v. Therefore, near the trough line, it is difficult to fully describe the change of the wind vector by simply using u or v. So define R:

[0114]

[0115] That is, the v component divided by the u component, which is a scalar. In the westerly belt, u>0, R can simply represent the numerical ratio of uv, and can also reflect the movement in the north-south direction through the sign of v. Since the revision point moves westward at the same latitude, the custom physical quantity R controls the westward movement range (such as Fig.15 In the westerly belt, U is always greater than 0. If the revision point is moved westward, it needs to be in the westerly belt area where R is negative. When V is negative, it is on the west side of the trough line; when V is positive, it is on the east side. The idea is as follows:

[0116] 1. The point that needs to be revised needs to be moved westward to obtain the starting point of the corrected groove line.

[0117] 2. When the starting and ending points of the trough line are moved westward, the appropriate positions to which they should be moved should be determined by spatial interpolation of the grid point R.

[0118] 3. Through comparative experiments, find the appropriate R value corresponding to the westward movement position.

[0119] Using the inverse distance weighted method, spatial interpolation is performed on the revision point in the same latitude (i.e., east-west) direction to obtain the corresponding R value at each location in the same latitude direction of the revision point.

[0120] For any point P(x,y) within four adjacent grid points, the inverse distance weighted interpolation formula is as follows:

[0121]

[0122] Among them, λ i is the weight of each grid point used in the prediction process, n is the number of grid points4, P t is the distance attenuation parameter. After comparative experiments, t =4, the effect is best, d i The distance from each grid point to the interpolation point:

[0123]

[0124] (x,y) is the coordinate of the interpolation point, (x i ,y i ) are the grid coordinates. To ensure the overall mathematical stability after processing, λ i The following conditions must be met:

[0125]

[0126] The spatial interpolation value in the same latitude direction of the revision point is determined based on the four grid point data adjacent to the revision point.

[0127] (1) Determine the row and column where the data corresponding to revision point P is located.

[0128] For a certain revision point P (x, y), according to the MICAPS 11th category data grid data storage rules, the positions of the four grid points around it can be calculated, and the longitude and latitude grid distance, starting and ending longitude and latitude and other parameters stored in the data file can be read out. From the 11th category data, the longitude is read as lond (lon-distance), the latitude is latd (lat-distance), the starting longitude is lonS, and the starting latitude is latS. The read data is processed in ascending order. The row and column where the point P (x, y) is located are Row and Col respectively. Substitute the above read data into formula (8) (9) to calculate the row and column where the point P is located, and take the integer and ignore the decimal:

[0129]

[0130]

[0131] In most cases, the calculated rows and columns are non-integers, which means that the point is not exactly on a row or column, but is within the grid composed of 4 data points. Therefore, the integer part of the value in (8) (9) above is taken and the decimal part is removed. The revised point P may coincide with a grid point, and the situation will be discussed later.

[0132] (2) Based on the determined initial rows and columns, determine the grid where point P is located, that is, the longitude and latitude of the adjacent grid points.

[0133] From the above analysis, we can know that point P is between Col, Col+1, Row, Row+1, thus determining the positions of the four grid points around this point.

[0134] Given the revision point P (x, y), we need to find where point P is in the two-dimensional longitude and latitude grid. Take the grid point C, which is adjacent to point P in the southwest direction, as the standard point, substitute the longitude and latitude of point P to calculate Col and Row. Take the integer and ignore the decimals to get the corresponding starting row and column, and get the longitude and latitude of grid point C, and then determine the longitude and latitude of grid points A, B, and D.

[0135] After getting the values ​​of Row and Col, we use them to calculate the longitude and latitude of the four grid points adjacent to point P. We can get:

[0136] The calculation formula for the position of point A is:

[0137] lon1=lonS+lond×Col (10)

[0138] lat1=latS+latd×(Row-1) (11)

[0139] The calculation formula for the position of point B is:

[0140] lon2=lons+lond×(Col+1) (12)

[0141] lat1=latS+latd×(Row+1) (13)

[0142] The calculation formula for the position of point C is:

[0143] lon1=lonS+lond×Col (14)

[0144] lat2=latS+latd×Row (15)

[0145] The calculation formula for the position of point D is:

[0146] lon1=lonS+lond×(Col+1) (16)

[0147] lat2=latS+latd×Row (17)

[0148] From the above formula, we can get the longitude and latitude of the four grid points. Fig.16 As shown, Fig.16 Get the positions of the four grid points A(lon1,lat1), B(lon2,lat1), C(lon1,lat2), and D(lon2,lat2).

[0149] Substituting the relevant parameters into formula (7) yields:

[0150]

[0151]

[0152] In formula (19), For (X i , Y i ). According to the physical quantity R of the 4 grid point data adjacent to the revised point, after comparative tests, the westward position Δ1 of S1 needs to satisfy R as close as possible to = -0.8 to determine the westward position and distance, which can make the revised point as perpendicular to the westerly belt as possible and make the revised point move westward at a more appropriate distance, which is both beautiful and reasonable.

[0153] In this embodiment, the case where the revision point S coincides with the adjacent grid point is discussed, such as Fig.17 As shown in the figure, S is the point to be revised, and A, B, C, and D are the adjacent grid points of S. If S coincides with any point of A, B, C, and D, the distance between a certain grid point and S is 0, and the calculation rules of the inverse distance weighted method cannot be applied because it cannot be used as a denominator; or it is on the straight line BD, AC, located at the edge of the interpolation area, and the interpolation effect is poor. When S coincides with BD: In order to solve this situation, Fig.18 As shown. Taking S coincident with B as an example, take the four grid points A', B', C', and D' adjacent to S in the northwest, southwest, northeast, and southeast, and perform the same calculation principle of interpolating the westward movement of the interpolation control point using the inverse distance weighted method based on the wind vector data to obtain S1. If S coincides with D, the same principle applies.

[0154] In this embodiment, Fig.19 As shown, Fig.19 The midpoint S coincides with the midpoint of BD. When S is on BD, the midpoint of BD can be used to determine whether it belongs to the coincidence B or the coincidence D situation and process it. If S is located at the midpoint and between the midpoint and B, the rule of S coinciding with B is adopted for processing. Otherwise, the rule of S coinciding with D is adopted for processing.

[0155] This situation does not occur when S coincides with AC or when S is on the AC longitude line, as it is avoided by the algorithm for obtaining the grid data.

[0156] In this embodiment, the corrected truncation point C is the end point of the northern trough line. In the westerly belt where the truncation point C is located, the R value is negative from point C to the west and positive from point C to the east. In order to move the truncation point westward, Cn is obtained in the same way as S1, as follows: Fig. 20 As shown in the figure, the interruption point C of the problematic trough line is moved west to Cn to complete the correction of the northern trough line, and then Cn is moved south a certain distance to Cs to determine the starting point of the southern trough line. It is more reasonable to move Cn southward by Δ2 = 0.7 latitudes to obtain Cs. Not only can the two trough lines and cold air be distinguished, but for the large-scale trough line weather system of thousands of kilometers, the correction of tens of kilometers also ensures that the error is completely controllable.

[0157] In this embodiment, the midpoint of the north-south trough line is revised. Since the two ends of the revised trough line have moved westward, the midpoint is moved eastward to achieve the convexity of the trough line. Fig.21 As shown in the figure, the midpoint moves eastward. Taking the northern section of the trough as an example, L is the distance between the interpolation control points S1 and Cn, and d is the distance from Mn0 to Mn. L / d reflects the change in the curvature of the trough. After comparing the actual results, it is decided that L / d=6 is the most reasonable. Mn is obviously moved eastward, and the vertex Mn of the convex northern section of the trough is obtained. While maintaining the beauty, the convexity of the trough in the forward direction is more reasonable. Therefore, the above-mentioned Mn point is compared with the intersection of the same latitude of the original problem trough. Fig. 22 As shown, the intersection point of the original problem trough line with the same latitude as point Mn is P, and the two adjacent points are P1 and P2. Our goal is to calculate the coordinates of point P. The Y coordinate is known to be the Y coordinate of point Mn (same latitude), and the key is how to find the intersection coordinate X.

[0158] In this embodiment, using the similar triangle rule, it can be known that the ratio of any corresponding line segments of similar triangles is equal to the similarity ratio.

[0159]

[0160] In formula (20), all are variables that can be calculated. Then, by using proportional operation, X can be calculated to obtain the coordinates of point P. Compare the coordinates of point P with the coordinates of Mn. If the value of point P is larger, then P is replaced by Mn, otherwise it remains unchanged. This ensures the convexity of the groove line after correction. The same detection method is also used for the subsequent Ms point.

[0161] In this embodiment, the moving method for the middle point Ms of the southern section of the trough line is consistent with the above.

[0162] The purpose of this embodiment is to make it bulge as eastward as possible. If the obtained Mn point is not as east as the point of the original trough line, the effect is poor, and point P is used to replace point Mn. The same applies to the southern section of the trough line Ms.

[0163] In this embodiment, the revision of the problem trough end point E, i.e., the end point of the southern section trough, is similar to the revision of C and S to obtain Cn and S1. Fig.23 As shown, in the westerly belt where the end point E is located, the area is smaller than that of C and S. After actual experimental comparison, it is determined that when Δ3 = 0.1, it is a more reasonable choice to take the R value as positive as possible and close to -0.1, and Es is obtained.

[0164] In this embodiment, a smooth and continuous correction groove line is formed by using third-order Bezier curve interpolation.

[0165] In this embodiment, S1, Mn, Cn; Cs, Ms, Es are used as interpolation control points to interpolate the north and south sections of the correction groove line respectively to form a smooth and continuous curve, which eventually becomes the desired correction groove line.

[0166] In this embodiment, the basic idea of ​​the present invention is to replace the straight lines connecting the points with smooth curves, and each segment of the curve has a smooth transition at the vertex.

[0167] In this embodiment, third-order Bezier interpolation can be used to form a curve, such as formula (21), or other interpolation methods can be used. When the actual input points are small, if other interpolation methods such as cubic spline interpolation are used, their accuracy and smoothness are inferior to third-order Bezier curve interpolation, and the effect is poor.

[0168]

[0169] The third-order Bezier curve can be described by a cubic function with two interpolation control points. It is better to use it to connect two points in a curve in terms of accuracy and aesthetics.

[0170] In this embodiment, a problem trough line at 500hPa at 8:00 am on September 9, 2020 is used for correction. Fig.24 and Fig.25 By comparison, we can see that the thick black solid line in the middle is the corrected trough line, the wavy line is the contour line, and area D is the low pressure center. The example shows that the correction of the trough line by using the wind field and potential field has achieved the purpose of correction.

[0171] The MICAPS data format is described below.

[0172] diamond 4 data description (string) year month day time time level (all integers) longitude grid interval latitude grid interval start longitude end longitude start latitude end latitude (all floating point numbers) latitude grid points number latitude grid points number (all integers) contour line interval contour line start value end value smoothing coefficient bold line value (all floating point numbers). Note: This type of data is used to draw contour lines for grid point data. The grid can be a longitude and latitude grid or a rectangular coordinate grid.

[0173] When using Cartesian grid data:

[0174] 1) Change the contour line end value to -1 (Cartesian coordinates under Lambert projection) or -2 (Cartesian coordinates under Mercator projection) or -3 (Cartesian coordinates under Northern Hemisphere projection).

[0175] 2) Change the grid longitude and latitude intervals to the longitude and latitude of the last point in the first row of the grid data.

[0176] 3) Change the starting longitude and starting latitude to the longitude and latitude of the first point in the first row of the grid data.

[0177] 4) Change the ending longitude and latitude to the longitude and latitude of the last point in the last row of the grid data.

[0178] The fourth type of data file can be used directly to fill in grid point values. The file header can specify the mapping method. The specification method is: 1) Change the bold line value to -1, indicating that contour lines are drawn and mapping is performed at the same time; 2) Change it to -2 to indicate that only mapping is performed without drawing contour lines. Data: Data is placed in the latitude direction first and then the longitude direction (for rectangular coordinate grids, the X direction is first and then the Y direction), all of which are floating point numbers.

[0179] diamond 11 data description (string) year month day time time level (all integers) longitude grid distance latitude grid distance starting longitude ending longitude starting latitude ending latitude (all floating point numbers) number of latitude grid points number of longitude grid points (all integers).

[0180] Note: This type of data is mainly used to draw streamlines in the wind field. The grid can be a longitude and latitude grid or a rectangular coordinate grid. When using a rectangular coordinate grid, the file header is modified as follows:

[0181] 1) Change the grid longitude and latitude intervals to the longitude and latitude of the last point in the first row of the grid data.

[0182] 2) Change the starting longitude and starting latitude to the longitude and latitude of the first point in the first row of the grid data.

[0183] 3) Change the ending longitude and latitude to the longitude and latitude of the last point in the last row of the grid data.

[0184] 4) Add a number to the longitude of the last point in the first row to indicate the rectangular coordinates under which base map projection: add 1000 for LAMBERT projection, 2000 for MECATOR projection, and 3000 for Northern Hemisphere projection. Data: Put the U component first, and put the data in the latitude direction first and then the longitude direction (if it is rectangular coordinate grid data, then the X direction first and then the Y direction), all of which are floating point numbers. Put the V component after all the U components of the grid points are put, and also put them in the latitude direction first and then the longitude direction.

[0185] diamond 14 data description (string) year, month, day, hour, time validity (all integers), Note: This type of data is automatically generated when saving the image editing results and can be used to generate the final forecast product.

[0186] data:

[0187] LINES: Number of lines

[0188] Line width points XY Z......

[0189] Number of labels XY Z......(If there is no label, it is NoLabel 0)

[0190] …………

[0191] LINES_SYMBOL: number of lines

[0192] coding

[0193] Line width points

[0194] XY Z......NoLabel 0

[0195] …………

[0196] SYMBOLS:Number

[0197] Encoded XYZ wind direction angle or string ......

[0199] CLOSED_CONTOURS: number

[0200] Line width points XY Z......

[0201] Number of labels XY Z......(If there is no label, it is NoLabel 0)

[0202] …………

[0203] STATION_SITUATION

[0204] Station number attributes ......

[0206] WEATHER_REGION: Number of weather regions

[0207] Weather code perimeter points for weather zones

[0208] XYZ…………

[0209] ………………………………

[0210] FILLAREA: Number of fill areas

[0211] Coded line points XYZ...

[0212] Fill type (line color) ARGB (foreground color) ARGB (background color) ARGB gradient color angle pattern code whether to draw a border

[0213] ………………

[0214] NOTES_SYMBOL: Number of annotations

[0215] Code XYZ Number of characters Character angle Font name Length Font name Font size Font type (color) ARGB

[0216] ………………

[0217] WithProp_LINESYMBOLS: Number of lines with properties

[0218] Encoded line width (line color) ARGB line type whether to add shadow display

[0219] Line point number XYZ...

[0220] Number of labels XY Z......(If there is no label, it is NoLabel 0)

[0221] ………………

[0222] Among them: LINES_SYMBOL represents weather system lines such as trough lines and cold fronts, and its codes are: 0, 1—trough line, 2, 6—cold front, 3, 7—warm front, 4—stationary front, 5—occluded front, 8—cold front in the past 12 hours, 9—warm front in the past 12 hours, 38—frost line, 39—high temperature line.

Claims

1. A method for correcting a type of erroneous westerly belt trough line, characterized in that: The following steps are involved: S1. Obtain wind field grid data, potential height field grid data and trough line data respectively, traverse each trough line data, calculate the curvature of each point on the trough line, and determine the problematic trough line using the curvature of each point; S2. Find the minimum curvature point of the problem slot line C , and take the minimum curvature point in the problem slot line C The data point is taken as the cutoff point, and the problem slot line is divided into two sections, north and south, using the cutoff point; S3. Traverse the potential height field contour lines in the area where the problem trough line is located, find and analyze the closed potential height contour lines, and read the starting point of the problem trough line ST The southernmost point on the closed geopotential height contour line S ; S4. Select the southernmost point based on wind vector data S The adjacent grid points are used to perform spatial interpolation of the user-defined function at the same latitude as the southernmost endpoint, and the position where the user-defined function tends to Δ1 is found according to the interpolation distribution of the user-defined function, and the southernmost endpoint is S Move west to this position and get the starting point of the corrected trough line in the northern section S1 , where Δ1 represents a custom function The value of , and Δ1=-0.8; The custom function The expression is as follows: in, and For each grid point Direction and Wind speed value in direction; S5. Use the selected grid points to truncate the custom function C Interpolate the same latitude space, and find the position where the custom function tends to Δ1 according to the interpolation distribution of the custom function, and truncate the cutoff point C Move westward to this position to obtain the end point of the corrected trench line in the northern section Cn ; S6. Determine the starting point of the revised trench line in the northern section S1 The end point of the groove line after the correction of the northern section Cn The midpoint of the line Mn0 , the midpoint of the line Mn0 Move eastward to get the vertex of the northern trough line Mn , and find the convex vertex of the northern trough line Mn The intersection of the same latitude and the problem trough line P , the intersection P The vertex of the convexity of the northern trough line Mn For comparison, if the intersection P At the apex of the convex trough line in the northern section Mn East side, the intersection P Replace the convex vertex of the northern trough line Mn Otherwise, keep the convex vertex of the northern trough line Mn constant; S7, correct the starting point of the trench line in the northern section S1 , the end point of the groove line after correction in the northern section Cn And the apex of the convex trough line in the north section Mn As interpolation control points, interpolation processing is performed to form a curve and obtain the correct groove line in the northern section; S8. Correct the ending point of the trench line in the northern section Cn Move down Δ2 degrees of latitude to get the starting point of the corrected trough line in the southern section Cs , the starting point of the corrected trench line in the southern section Cs The end point of the problem slot line E The midpoint of the line Ms0 Move eastward to obtain the vertex of the convex groove line after correction in the southern section Ms , and find the vertex of the convex groove line after correction in the southern section Ms Intersection point with the problem trough P , the intersection P The vertex of the convex front of the southern trough line Ms For comparison, if the intersection P At the apex of the convex trough line in the southern section Ms East side, the intersection P Replace the apex of the convex front of the southern trough line Ms Otherwise, keep the convex vertex of the southern trough line Ms unchanged, where Δ2 represents the displacement degree of latitude, and Δ2=0.7; S9. Use the selected grid points to perform the problem slot end point analysis on the custom function. E Interpolate the space at the same latitude, find the position where the custom function approaches Δ3 according to the interpolation distribution of the custom function, and move the end point of the problem slot line to E Move west to this position and obtain the corrected trench end point of the southern section Es , where Δ3 represents the value of the custom function R, and Δ3=-0.1; S10, correct the end point of the trench line in the southern section Es , the apex of the convex front of the southern section of the trough Ms The starting point of the trough line after the correction of the southern section Cs As the interpolation control point, interpolation processing is performed to form a curve and obtain the correct groove line of the southern section.

2. The method for correcting a type of erroneous westerly belt trough line according to claim 1, characterized in that: The step S1 comprises the following steps: S101, respectively obtaining wind field grid data, geopotential height field grid data and trough line data; S102, traverse the data of each slot line and calculate the curvature of each point on the slot line : S103, determine the curvature of each point on the groove line Are all positive? If so, the slot line is normal, check the next slot line, and return to step S102. Otherwise, the curvature of a point on the slot line If it is negative, the slot line is defined as a problematic slot line and the process goes to step S2.

3. The method for correcting a type of erroneous westerly belt trough line according to claim 1, characterized in that: The step S3 comprises the following steps: S301, traversing the potential height field contour lines in the area where the problem trough line is located, and obtaining all the closed contour lines of the potential height field; S302, determine the starting point of the problem slot line Is it within the closed contour area of ​​the geopotential height field? If so, take the southernmost point on the closed contour line as S , and go to step S4, otherwise, the potential height field closure contour is not closed, and the starting point of the problematic trough line is As the southernmost point , and proceed to step S4.

4. The method for correcting a type of erroneous westerly belt trough line according to claim 1, characterized in that: The step S4 comprises the following steps: S401. Customize a function for each grid point based on wind vector data ; S402: Determine the southernmost point Is it on the grid? If so, take the southernmost point The four adjacent northwest, southwest, northeast and southeast grid points of the , and go to step S403, otherwise, take the southernmost point The four adjacent grid points of east, south, west and north, and proceed to step S403; S403, according to the four adjacent grid points, the user-defined function The southernmost point Spatial interpolation at the same latitude, and according to the custom function Find a custom function for the interpolation distribution tend to The southernmost point Move westward to this position to obtain the starting point of the corrected groove line in the northern section and proceed to step S5.

Images