CN111650673A

CN111650673A - Method for correcting central position of low vortex by using wind field data

Info

Publication number: CN111650673A
Application number: CN202010505143.3A
Authority: CN
Inventors: 胡文东; 舒红平; 丁禹钦; 张莹; 罗飞; 张宇; 邵建; 华维; 贾净翔; 徐文嘉
Original assignee: Chengdu University of Information Technology
Current assignee: Chengdu University of Information Technology
Priority date: 2020-06-05
Filing date: 2020-06-05
Publication date: 2020-09-11
Anticipated expiration: 2040-06-05
Also published as: CN111650673B

Abstract

The invention provides a method for correcting the central position of a low vortex by using wind field data, which comprises the steps of firstly, analyzing a closed potential height contour line by using a potential height field, screening and judging a low vortex area, and then finding an innermost contour line in the low vortex area; calculating the vorticity data through a wind field, positioning a point with the maximum vorticity value in the range of the innermost ring of the low vortex, and recording the point as a low vortex extreme point; and finally, judging by using the low vortex extreme point and wind field information in adjacent data points around the low vortex extreme point. Through the design, the problem that the accurate position of the low vortex center cannot be automatically corrected in the high-altitude isobaric surface is solved, the analysis efficiency and the positioning precision are improved, and a solid foundation is laid for realizing precise and accurate automatic analysis and prediction.

Description

Method for correcting central position of low vortex by using wind field data

Technical Field

The invention belongs to the technical field of meteorology, and particularly relates to a method for correcting the central position of a low vortex by using wind field data.

Background

Low-vortex is one of the important high-altitude weather systems affecting precipitation and appears as a cyclonic circulation on an isobaric surface, i.e. the wind in the low-vortex region rotates counterclockwise in the wind field. The low vortices have a group or at least one contour in the low value region of the potential height field closed contour, with higher outside values and lower inside values, in which region the outer most contour tends to represent the extent of the low vortices, with the center of the low vortices lying within the inner most contour. Potential height field analysis is commonly used in meteorological operations to determine low vortices in the air. Until now, the forecast personnel still perform manual operation according to self experiences in a man-machine interaction mode in the meteorological service for judging the position of the low vortex center, and a series of related defects of strong subjectivity and low analysis efficiency are existed from person to person.

At present, the spatial resolution of the China meteorological office grid forecast is 5 kilometers nationwide, and the number of China high altitude detection stations is 124, as shown in FIG. 1, dots in FIG. 1 are high altitude detection stations in China, and the total number is 124; the west and the Qinghai-Tibet plateau areas are quite sparse, and the high-altitude detection stations marked at the two ends of the arrow are respectively positioned at the Lhasa and the civil Feng detection station at the upstream of the weather, and the distance is 1138 kilometers. The average spatial resolution of high-altitude data is 279 kilometers according to the area of 960 tens of thousands of square kilometers of the territorial earth (excluding territorial waters such as the territorial sea and the like). The high altitude of most high latitude areas in China is in the west wind zone, weather stations in western areas of the upstream of the weather in China are quite sparse, the distances between the stations in the western and Qinghai-Tibet plateau areas are far, the average spatial resolution of high altitude data in the Tibet autonomous region is 490 kilometers, and the average spatial resolution of the Xinjiang Uygur autonomous region is 344 kilometers. The sparse station distribution makes the accurate positioning of a weather system very difficult, for example, the distance between a Lhasa sounding station and a civil Feng station at the upstream of the weather reaches 1138 kilometers, which is far higher than the average resolution of high-altitude data in China. Even if the southeast area of China is relatively dense, the spacing distance is up to hundreds of kilometers, and the positioning error of a weather system is obvious. According to the 2.5 longitude and latitude resolution data commonly used by the weather information comprehensive processing system (MICAPS), the distance between numerical points is more than 250 kilometers. Considering that the spatial resolution of grid forecast in China is 5 kilometers, more than 50 forecast data point deviations can be caused in a single direction, and therefore, the forecast of 2500 area units in total of 50 multiplied by 50 of a two-dimensional plane causes significant errors, and therefore, weather analysis without accurate positioning can bring huge influence.

Therefore, although the low vortex center can be determined to be located in the potential height field contour line of the innermost circle, the area is often hundreds to thousands of square kilometers, and other data except the potential height field, such as a wind field, needs to be combined at specific places to accurately position, so that the positioning precision is improved. For the center of the low vortex, the weather in different areas in the low vortex is greatly different, so that the accurate positioning of the center of the low vortex has important indication significance for weather analysis, diagnosis and forecast.

Disclosure of Invention

Aiming at the defects in the prior art, the method for correcting the center position of the low vortex by using the wind field data solves the problem that the center of the low vortex cannot be automatically judged and marked in the high-altitude isobaric surface, and lays a solid foundation for realizing precise and accurate automatic analysis and prediction.

In order to achieve the above purpose, the invention adopts the technical scheme that:

the scheme provides a method for correcting the central position of a low vortex by using wind field data, which comprises the following steps:

s1, acquiring potential height data point data and wind field data point data, generating a wind vector by using the wind field data point data, and generating a potential height field contour line by using the potential height data point data;

s2, traversing the potential height field contour lines, eliminating non-closed contour lines and screening out closed contour lines;

s3, traversing the closed contour line and selecting a low vortex area;

s4, traversing the closed contour line in the low vortex region to obtain a low vortex innermost contour line, and recording the low vortex innermost contour line as a low vortex core contour line;

s5, traversing all data points in the low vortex core contour line to obtain the vorticity value of each data point, and judging whether the number of the data points with the maximum vorticity value is greater than 1, if so, entering a step S6, otherwise, entering a step S7;

s6, calculating the average position of a plurality of data points with the maximum vortex value at the same time, recording the average position as a low vortex center, and taking the low vortex center as the corrected low vortex center to finish the correction of the low vortex center position;

s7, recording the only data point with the maximum vorticity value as a low-vorticity extreme point O;

and S8, performing correction vector product calculation on the low vortex extreme point O and adjacent data points around the low vortex extreme point O according to the wind vector, and correcting the center position of the low vortex according to the calculation result.

The invention has the beneficial effects that: because the extreme value of the low vortex is determined to be near the low vortex center, the low vortex center is identified in meteorology through the wind field, principle errors can occur without using the wind field for positioning, and the low vortex center and the low vortex extreme point positioned through the wind field have deviation, so that in order to eliminate the deviation, the position of the low vortex center is corrected.

Further, the conditions satisfied by the closed contour in step S2 are as follows:

x₀≠lon_min∧x₀≠lon_max∧x_n≠lon_min∧x_n≠lon_max∧y₀≠

lat_min∧y₀≠lat_max∧y_n≠lat_min∧y_n≠lat_max

wherein, lon_minAnd lon_maxAll represent longitudinal boundaries, lat_minAnd lat_maxAll represent latitude boundaries, x₀And y₀Representing the longitude and latitude, x, of the starting point in the contour_nAnd y_nRepresenting the longitude and latitude of the termination point in the contour.

The beneficial effects of the further scheme are as follows: the low vortex exists in a low-value area of a closed contour on a potential height field, and low-value judgment needs to be carried out on the closed contour, so that the center of the low vortex can be accurately screened out.

Still further, the step S3 includes the steps of:

s301, searching data points from bottom to top and from left to right in a closed contour range, and marking the first searched data point as an M point;

s302, judging whether the potential height value of the point M is smaller than that of the closed contour line, if so, marking the area in the range of the closed contour line as a low-vortex area, and proceeding to the step S4, otherwise, not marking the area as the low-vortex area, and skipping the closed contour line.

The beneficial effects of the further scheme are as follows: the method and the device judge whether the potential height in the closed contour is lower than the value of the closed contour or not so as to judge the low value, and can determine the low vortex area more accurately.

Still further, the step S4 includes the steps of:

s401, when only one closed contour line exists in a low vortex region, marking the closed contour line as a low vortex core contour line; or

When two or a plurality of closed contour lines exist in the low vortex area, marking the two or the plurality of closed contour lines as L₁,L₂,L₃,...,L_nAnd proceeds to step S402, where L_nIndicating n closure etcA value line;

s402, judging the nesting relation of any two marked closed contour lines;

and S403, obtaining the contour line of the lowest vortex inner ring according to the nesting relation judgment result, and recording the contour line of the lowest vortex inner ring as a low vortex core contour line.

The beneficial effects of the further scheme are as follows: the low vortex center exists within the contour of the innermost circle, and therefore, in order to accurately locate the low vortex center, the contour of the innermost circle needs to be acquired.

Still further, the step S402 includes the steps of:

s4021, recording the east point in a closed contour as X_maxMost western point is X_minThe most northern point is Y_maxAnd the south-most point is Y_min；

S4022, judging the closed contour L after any two marks_iAnd L_jWhether or not X is satisfied_{i max}>X_{j max}∧X_{i min}<X_{j min}∧Y_{i max}>Y_{j max}∧Y_{i min}<Y_{j min}If so, the contour L is closed_jIs a closed contour line L_iCompleting the judgment of the nesting relation, otherwise, returning to the step S4021, wherein X_{i max}And X_{j max}Respectively represent a closed contour line L_iAnd L_jMost eastern point of (1), X_{i min}And X_{j min}Respectively represent a closed contour line L_iAnd L_jMost west of (1), Y_{i max}And Y_{j max}Respectively represent a closed contour line L_iAnd L_jThe most northern point of (A), Y_{j max}And Y_{j min}Respectively represent a closed contour line L_jAnd L_jThe south-most point of (c).

The beneficial effects of the further scheme are as follows: the closed contour lines in the low vortex area are compared pairwise according to the nesting relation, and the contour line of the innermost circle can be effectively obtained.

Still further, the step S5 includes the steps of:

s501, traversing any data point in the low vortex core contour line, and if the potential height of the point is smaller than the low vortex core contour line, entering the step S503;

s502, bringing adjacent data points outside the low vortex core contour line into screening of auxiliary analysis points, and entering step S503;

s503, carrying out vorticity calculation on data points inside the closed contour line to obtain a vorticity value;

the expression for the vorticity value is as follows:

where ζ represents the vorticity value at (i, j) where the data points are concentrated, i represents a column, j represents a row, v represents a component on the y-axis, u represents a component on the x-axis, and x (i, j) and y (i, j) represent the longitude and latitude at (i, j), respectively.

S504, traversing and screening the points with the maximum vortex value, judging whether the number of the data points with the maximum vortex value is larger than 1, if so, entering a step S6, otherwise, entering a step S7.

The beneficial effects of the further scheme are as follows: the method screens out the low-vorticity area by utilizing the contour lines of all potential height fields, positions the maximum vorticity value point in the low-vorticity area by utilizing the vorticity value, and can effectively reduce the correction deviation in the subsequent steps.

Still further, the step S8 includes the steps of:

s801, recording 8 data points adjacent to the low vortex extreme point O as auxiliary analysis points, and recording the auxiliary analysis points as A, B, C, D, E, F, G and H points respectively;

s802, eliminating anti-cyclone interference, respectively calculating the vorticity between the low-vortex extreme point O and the auxiliary analysis points to obtain a vorticity value, judging whether the vorticity value is greater than 0, if so, keeping the auxiliary analysis points corresponding to the vorticity value, and entering a step S803, otherwise, deleting the auxiliary analysis points corresponding to the vorticity value, and entering the step S803;

s803, judging whether all the auxiliary analysis points are traversed, if so, entering the step S804, otherwise, returning to the step S802;

s804, according to the wind vectors, correcting vector product calculation is carried out on the low vortex extreme point O and each reserved auxiliary analysis point respectively to obtain a correcting vector product C_rAnd determining the corrected vector product C_rIf the number of the data is larger than 1, the step S805 is executed, otherwise, the step S806 is executed;

s805, calculating the maximum correction vector product C_rThe longitude and latitude average values of the points and the low vortex extreme points O are obtained, and the points obtained by the longitude and latitude average values are marked as low vortex centers to finish correction of the low vortex center positions;

s806, correcting the maximum vector product C_rAnd the midpoint of the connecting line of the point (A) and the low vortex extreme point O is marked as a low vortex center, and the correction of the low vortex center is completed.

The beneficial effects of the further scheme are as follows: the invention combines the low vortex extreme point positioned by the vorticity with the low vortex center positioned by the wind field, accurately positions the low vortex center in the low vortex system and achieves the aim of correcting the low vortex center.

Still further, the expression of the vorticity value in step S802 is as follows:

therein, ζ_NRepresenting the vorticity value, N representing the set of auxiliary analysis points, v_ORepresenting the component of the low eddy limit point O in the y-direction, v_NRepresenting the component of the auxiliary analysis point in the y-direction, x_OAnd y_OLatitude and longitude, x representing the low eddy extreme point O_NAnd y_NRepresenting the component of the auxiliary analysis point in the x-direction, u_OComponent, u, of the wind vector in the x-direction representing the low vortex extreme point O_NRepresenting the component of the wind vector of N in the x direction.

The beneficial effects of the further scheme are as follows: the invention positions the maximum vorticity value point in the low-vorticity area by utilizing the vorticity value, and can effectively reduce the correction deviation in the subsequent steps.

Still further, the expression of the modified vector product in step S804 is as follows:

wherein, C_rRepresents the product of the correction vector, V_aAnd V_bAll represent wind vectors, theta represents the angle between two wind vectors, u_aAnd u_bAll represent wind vector V_aComponent of (a), v_aAnd v_bAll represent wind vector V_bThe component (c).

The beneficial effects of the further scheme are as follows: the method performs correction vector product calculation by depending on the low vortex extreme point and the wind vector on the auxiliary analysis point, further screens out the position with the maximum wind vector rotation degree, and further reduces the deviation of the low vortex center.

Still further, in step S805 or step S806, the longitude and latitude expression of the low vortex center is as follows:

wherein, W_xLongitude, W, representing the center of the low vortex_yIndicates the latitude of the center of the low vortex, (x)_o,y_o) Represents the latitude and longitude of the low-eddy extreme point O, t represents the number of the reserved auxiliary analysis points, (x)_i,y_i) Representing the point C with the largest correction vector product_rXX denotes the set of remaining auxiliary analysis points.

The invention has the beneficial effects that: the invention provides a good condition for correcting the low vortex center by calculating the average value of the longitude and the latitude of the plurality of points with the maximum correction vector product and the longitude and the latitude of the low vortex extreme point O.

Drawings

FIG. 1 is a distribution diagram of a high altitude detection station in China in the background art.

FIG. 2 is a flow chart of the method of the present invention.

FIG. 3 is a schematic diagram of 500hPa low vortex in this embodiment.

Fig. 4 is a schematic view of the wind vector in this example.

Fig. 5 is a schematic diagram of the wind vector V decomposition of u and V wind in the x and y directions in the present embodiment.

Fig. 6 is a schematic distribution diagram of the non-closed contour line in this embodiment.

FIG. 7 is a diagram illustrating that point M is any one data point in the closed contour line in this embodiment.

FIG. 8 is a closed contour line L in this embodiment_iAnd L_jSchematic diagram of the nesting relationship of (1).

FIG. 9 is a schematic diagram of the distribution of the inner and outer points of the median line in this embodiment.

Fig. 10 is a schematic diagram of the low vortex limit point O and the 8 neighboring auxiliary analysis points around the low vortex limit point O in this embodiment.

FIG. 11 is a diagram illustrating the vector angle and the vector product of wind in this embodiment,

Fig. 12 is a schematic diagram illustrating counterclockwise rotation of the two-dimensional vectors a to b in the present embodiment.

Fig. 13 is a schematic diagram illustrating that the two-dimensional vectors a to b are rotated clockwise in the present embodiment.

FIG. 14 is an image of the angle θ when the vector product is greater than or equal to 0 in the present embodiment.

Fig. 15 is a schematic diagram illustrating a modified vector product in the present embodiment.

FIG. 16 is a diagram of the modified vector product C in this embodiment_rAnd (3) an image of angle theta at 0 or more.

Fig. 17 is a schematic diagram of ζ in calculating the vorticity value in the present embodiment.

Fig. 18 is a schematic view of the location of the low vortex center into the anti-cyclone in this embodiment.

FIG. 19 shows a graph of the equation C in this embodiment_rAThe distribution of the low vortex center W at maximum is shown schematically.

FIG. 20 shows a view of example C_rA、C_rC、C_rEThe distribution of the low vortex center W is shown in the maximum corrected vector product.

Fig. 21 is a schematic diagram of an example of correction in this embodiment.

FIG. 22 is a schematic diagram of vorticity values obtained by vorticity calculation of data points inside a closed contour line in this embodiment.

Detailed Description

The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.

Examples

As shown in fig. 2, the present invention provides a method for correcting the central position of low vortex by using wind farm data, which is implemented as follows:

s2, traversing potential height field contour lines, eliminating non-closed contour lines, and screening out closed contour lines;

s3, traversing the closed contour line, and selecting a low vortex area, wherein the implementation method comprises the following steps:

s302, judging whether the potential height value of the point M is smaller than that of the closed contour line, if so, marking the area in the range of the closed contour line as a low-vortex area, and entering the step S4, otherwise, not marking the area as the low-vortex area, and skipping the closed contour line;

s4, traversing the closed contour line in the low vortex area to obtain a low vortex innermost contour line, and recording the low vortex innermost contour line as a low vortex core contour line, wherein the implementation method comprises the following steps:

When two or a plurality of closed contour lines exist in the low vortex area, marking the two or the plurality of closed contour lines as L₁,L₂,L₃,...,L_nAnd proceeds to step S402, where L_nRepresenting n closed contour lines;

s402, judging the nesting relation of any two marked closed contour lines, wherein the implementation method comprises the following steps:

S4022, judging the closed contour L after any two marks_iAnd L_jWhether or not X is satisfied_{i max}>X_{j max}∧X_{i min}<X_{j min}∧Y_{i max}>Y_{j max}∧Y_{i min}<Y_{j min}If so, the contour L is closed_jIs a closed contour line L_iCompleting the judgment of the nesting relation, otherwise, returning to the step S4021, wherein X_{i max}And X_{j max}Respectively represent a closed contour line L_iAnd L_jMost eastern point of (1), X_{i min}And X_{j min}Respectively represent a closed contour line L_iAnd L_jMost west of (1), Y_{i max}And Y_{j max}Respectively represent a closed contour line L_iAnd L_jThe most northern point of (A), Y_{j max}And Y_{j min}Respectively represent a closed contour line L_jAnd L_jThe south-most point of (c);

s403, obtaining the contour line of the lowest vortex inner ring according to the nesting relation judgment result, and recording the contour line of the lowest vortex inner ring as a low vortex core contour line;

s5, traversing all data points in the low vortex core contour line to obtain the vorticity value of each data point, and judging whether the number of the data points with the maximum vorticity value is greater than 1, if so, entering a step S6, otherwise, entering a step S7, wherein the implementation method comprises the following steps:

s503, calculating the vorticity of the data points inside the closed contour to obtain a vorticity value, as shown in fig. 22, where the expression of the vorticity value is as follows:

S504, traversing and screening the points with the maximum vorticity value, judging whether the number of the data points with the maximum vorticity value is greater than 1, if so, entering a step S6, otherwise, entering a step S7;

s8, according to the wind vector, performing correction vector product calculation on the low vortex extreme point O and the adjacent data points around the low vortex extreme point O, and correcting the center position of the low vortex according to the calculation result, wherein the realization method comprises the following steps:

s804, according to the wind vector, the low vortex extreme value point O and each reserved auxiliary analysis point are respectively subjected to correction vector product calculation to obtain a correction vector product C_rAnd determining the corrected vector product C_rIf the number of the data is larger than 1, the step S805 is executed, otherwise, the step S806 is executed;

In this embodiment, the low vortex has a clear expression in the potential height field: in the closed contour, there is a group or at least one contour, the outer part is high and the inner part is low, the low vortex presents a cyclone distribution on the wind field, namely a counterclockwise distribution, as shown in fig. 3, the line in fig. 3 is the potential height field contour, the wind vector represents the wind direction and the wind speed, the round point is the center of the low vortex, and the square point is the geometric center of the low vortex. The weather chart expresses the wind direction and the wind speed by the wind vector which is composed of a wind direction rod and wind feather. The wind direction pole indicates the incoming direction of the wind, and the wind feather indicates the wind speed by a long dashed line, a short dashed line or a wind triangle and is perpendicular to one side of the tail end of the wind direction pole in the clockwise direction. One long dash line represents 4 m.s^-1And a dashed line represents 2 m.s^-1Wind triangle represents 20 m.s^-1As shown in FIG. 4, the wind direction rod indicates the direction of the wind, and the wind plume indicates the wind speed.

In this implementation, the potential height field may represent the area and extent of the low vortices, and if the extent of the low vortices is large and the wind field is complex, the centers of the low vortices tend to be offset from the centers of their geometric areas. The size of the vorticity value is reflected on the data point, and if the low vortex center is positioned only by using the vorticity value, the low vortex center is certainly positioned on the data point, which is not in accordance with the actual situation, so that the accurate positioning must be carried out by a wind field. As shown in fig. 3, if the contour analysis is performed only according to the potential height field, the square point is the geometric center of the contour; however, observing the cyclone distribution of the wind field can find that the center of the low vortex system is actually positioned at a circular point, so that the correction of the center of the low vortex system is realized by the wind field.

In this embodiment, as shown in fig. 5, potential height data point data and wind field data point data are read, where the wind field data are u wind and V wind, the u wind is in the x direction, the V wind is in the y direction, and after the combination, the wind field data is a wind vector V, and a potential height contour line can be generated by using the potential height data. Potential height contours can be divided into two categories: closed contour lines and non-closed contour lines. Low vortices appear on the closed contour in the potential height field, so that the closed contour is screened first to locate low vortices. And traversing all contour lines, excluding non-closed contour lines, and enabling the rest contour lines to be closed contour lines. As shown in fig. 6, there are 3 categories of non-closed contours:

(1) the start and end points of the contour are located on the same side of the map boundary (a contour in fig. 6).

(2) The start and end points of the contour are located on opposite sides of the map boundary (b contour in fig. 6).

(3) The start and end points of the contour are located on adjacent sides of the map boundary (c-contour in fig. 6).

The common points of the above 3 cases are: the start and end of the non-closed contour are both on the map boundary. In FIG. 6, lon_minAnd lon_maxAll represent longitudinal boundaries, lat_minAnd lat_maxAll represent latitude boundaries, and the coordinates of points on the contour are (x)_i,y_i) I is more than or equal to 0 and less than or equal to n, and the longitude and latitude of the starting point in the contour line are (x)₀,y₀) The longitude and latitude of the termination point is (x)_n,y_n). If the relationship is satisfied: x is the number of₀≠lon_min∧x₀≠lon_max∧x_n≠lon_min∧x_n≠lon_max∧y₀≠lat_min∧y₀≠lat_max∧y_n≠lat_min∧y_n≠lat_maxThe contour is determined to be closed.

In this embodiment, the low vortex exists in a low-value region of the closed contour on the potential height field, and the low-value determination needs to be performed on the closed contour, so that the low vortex is screened out. There are two cases of potential heights within the closed contour, either above or below the value of the closed contour. Performing low value judgment, namely judging whether the potential height in the closed contour is lower than the value of the closed contour or not, and dividing into two steps;

(1) searching data points from bottom to top and from left to right in the closed contour range, wherein the first searched data point is marked as M point, as shown in FIG. 7;

(2) if the potential height value of the M point is smaller than the potential height value of the contour line, the region in the range of the contour line is a low vortex region; and if the potential height value of the M point is greater than that of the contour line, the M point is not marked as a low vortex region.

In this embodiment, in the low vortex region, the contour line of the outermost ring represents the range of the low vortex, the center of the low vortex exists within the contour line of the innermost ring, and the contour line of the innermost ring is referred to as a low vortex core contour line. To accurately locate the low vortex center, the innermost contour needs to be acquired. Acquiring a low vortex core contour line:

(1) if only one closed contour line exists in the low vortex region, the contour line is directly judged to be a low vortex core contour line; if 2 or a plurality of closed contour lines exist in the low vortex area, marking the closed contour lines as L₁,L₂,L₃,...,L_n；

(2) Judging the nesting relation of any two marked closed contour lines; recording the east point in a closed contour line as X_maxMost western point is X_minThe most northern point is Y_maxAnd the south-most point is Y_min(ii) a If any two marked closed contour lines L_iAnd L_jI is not equal to j, i is more than or equal to 0 and is less than or equal to n, j is more than or equal to 0 and is less than or equal to n, and the relation is satisfied: x_{i max}>X_{j max}∧X_{i min}<X_{j min}∧Y_{i max}>Y_{j max}∧Y_{i min}<Y_{j min}Then, determine L_jIs L_iAs shown in FIG. 8, L in FIG. 8₂Is L₁The inner ring of (a);

(3) comparing the closed contour lines in the low vortex region in pairs according to the method in the step (2), finally obtaining the contour line of the innermost circle, and recording the contour line as a low vortex core contour line L_core。

In this embodiment, in order to cooperate with the correction work of the subsequent wind field, the low-vortex core contour line L needs to be located_coreThe point with the largest vorticity value is screened out internally and is marked as the low-vorticity extreme point. The steps of judging and screening the low vortex extreme point are as follows:

(1) judging all data points and low vortex core contour line L_coreIf a data point is on the low vortex core contour L_coreIf so, the point enters the step (3) for judgment; otherwise, the point does not proceed to step (3).

(2) Low vortex core contour line L_coreA closed contour line with data points on two adjacent sides, and a low vortex core contour line L for accurate correction_coreThe data points adjacent to the outer side are included in the screening of the subsequent auxiliary analysis points, and the step (3) is entered. As shown in FIG. 9, the points outside the contour are represented by dots, and the points inside are represented by squares;

(3) calculating the vorticity of the square points to obtain a vorticity value, traversing and screening out the point with the maximum vorticity value, and recording the point as a low-vortex extreme point O; if 2 or a plurality of points with the maximum vortex value exist at the same time, the longitude and latitude of the points are calculated averagely, the calculation result is directly marked as the correction low vortex center W, and the correction of the low vortex center is completed. In fig. 9, point a has the largest vorticity value among points a, b, c, and d, and therefore point a is referred to as low-vorticity point O.

In the present embodiment, the low vortex limit point O has the largest vortex value in the low vortex region, and the low vortex center is also in the vicinity thereof. In order to correct the low vortex center accurately, auxiliary analysis of the adjacent points of the low vortex extreme point O is needed. The 8 adjacent points around the low vortex limit point O were regarded as auxiliary analysis points and respectively designated as A, B, C, D, E, F, G, H points. As shown in fig. 10, the circle data point is the auxiliary analysis point, and the square point is the low vortex limit point O.

In this embodiment, the low vortex extreme point is located, the auxiliary analysis point is set, and vector product calculation is performed by using the low vortex extreme point and the wind vector on the auxiliary analysis point, so as to screen out the position where the wind vector has the maximum rotation degree. As can be seen from FIG. 11, if the classical vector product is used, the included angle between the two wind vectors is

When the vector product has the maximum value; to exceed

After that, the result gradually decreases to 0. To prevent false determination of the low vortex center, the cross product should be corrected.

The invention takes the vector product calculation as a key step, and the mathematical idea is as follows: two-dimensional vectors a, b, if the value of the vector product a x b is positive, indicating that the vectors a to b rotate counterclockwise; if the value of a × b is negative, it means that the vectors a to b rotate clockwise, as shown in fig. 12-13, a × b > 0 in fig. 12 is positive, the vectors a to b rotate counterclockwise, a × b < 0 in fig. 13 is negative, and it means that the vectors a to b rotate clockwise. The formula of a × b is:

in practical cases, the vectors a and b are two wind vectors, denoted as V₁、V₂(ii) a Its component in the x-axis direction is denoted u₁、u₂(ii) a Component in the y-axis direction, denoted v₁、v₂. The above formula can be written as:

when the two vectors are perpendicular to each other, the vector product of the two vectors has the maximum value; when the two vectors are parallel, the vector product of the two vectors has a minimum value of 0, as shown in FIG. 14In FIG. 14, θ is the angle between two wind vectors, C_maxThe maximum value of the vector product and the minimum value of 0. Similarly, when the included angle of two wind vectors is close to 180 °, the vector product of the two is small, but the rotation degree of the wind is large, and in the low vortex system, the low vortex center should be near the two wind vectors. If the screening judgment is carried out only by means of the vector product calculation, the misjudgment of the low vortex center can occur, and therefore the vector product should be corrected. As shown in FIG. 15, θ₁＝θ₄θ₂＝θ₃，|V₄|＝|V₂|，V₁And V₃Between them form an included angle of

V₁×V₃Has a maximum value; v₁×V₂And V₁×V₄Are equal in value. If the included angle between the two wind vectors is more than 0 and less than or equal to

Calculating according to a classical vector product mode; if the included angle between the two is larger than

And when the value is less than or equal to pi, adding an adaptive variable to correct the result, so that the result can correctly reflect the rotating property of the airflow in the low vortex. Two wind vectors V are simulated_a、V_bThe components are respectively u_a、v_aAnd u_b、v_bTo calculate the angle θ between the two wind vectors, there is a formula:

the domain of the arccos function f (x) arccos x is [ -1,1 []The value range is [0, pi ]]. Correcting wind vector C_rComprises the following steps:

when theta is equal to pi, the correction vector product C is directly judged_rIs the maximum value. As shown in FIG. 16, θ is in the range of 0 to

Value of time is V_a×V_bTheta is in

To a value of pi

The method of the present invention that utilizes a vector product is referred to as a modified vector product. Vorticity may describe the degree of rotation of a wind field in the atmosphere, and in a two-dimensional isobaric surface, vorticity may be expressed as:

the above formula shows that: the amount of change in the x direction of the v wind and the amount of change in the y direction of the u wind determine the magnitude of the vorticity. The approximate position of the center of the low vortex can be expressed through the vorticity value, and the low vortex center can be preliminarily fixed on a certain point by utilizing the low vortex core contour line and the vorticity maximum value. But has the disadvantages that: the vorticity value can only be expressed on the numerical point obtained by calculation, and the low vortex center determined by the vorticity value is always on the maximum vorticity value point, but the core of the low vortex is essentially the vortex motion of the atmosphere, so the real low vortex center is always on the atmosphere rotation center near the point, but not on the point. As shown in fig. 17, points inside the contour are squares, points outside the contour are dots, the vorticity value ζ of the squares is calculated, and the maximum vorticity value point, which is point a in the figure, is selected, and in fig. 9, the system is a low vortex system having a low vortex center at the atmospheric rotation center. The low vortex centers should therefore be between points a, b, c, d in the figure, and not at any one point. Calculating the vorticity to obtain the point a with the maximum vorticity value, wherein the low vortex center is also close to the point a; and then calculating the correction vector product of the point a and the auxiliary analysis point to obtain the maximum correction vector product between the points a and d, wherein the most suitable point is the midpoint of a connecting line of the points a and d. And the corrected vector product can be used for further correcting the more accurate geographical position of the low vortex center on the basis of the vorticity value. When the wind vector rotation degree is judged, the correction vector product of the wind vector is designed and the anti-cyclone is eliminated, which is the core protection point of the application.

In this embodiment, due to the complexity of the wind field, the low vortex center may be located in the anti-cyclone according to the modified vector product method, as shown in fig. 18, the contour line of the point O in fig. 18 represents the low vortex, and the anti-cyclone is located between the points O, D, and if the low vortex center is located between the points O, D according to the modified vector product method, a principle error may occur. Therefore, the vorticity between the low vortex extreme point O and the auxiliary analysis point is calculated separately in order and is recorded as ζ_N(N is the set of auxiliary analysis points). The calculation formula is as follows:

in the above formula, u and v are the components of the wind vector in the x and y directions, x_i、y_iCoordinates of the latitude and longitude of the data point. If ζ_N>0, the auxiliary analysis point is reserved; on the contrary, if ζ_N<0, the auxiliary analysis point is deleted.

In this embodiment, the wind vector of the point O is corrected to the wind vector of the reserved auxiliary analysis point by the vector product C_rCalculating to obtain C_rX(X is the set of auxiliary analysis points retained). Screening out C_rXMaximum value of (1), if a certain C_rXIf there is a maximum value, the midpoint of the line connecting the point X and the point O is defined as the low vortex center W. As shown in FIG. 19, if C_rAIs at a maximum and only C_rAAnd if the maximum value is reached, the midpoint of the connecting line of the point A and the point O is recorded as a low vortex center W, and the low vortex center is positioned.

In this embodiment, if the correction vector products of 2 or more points are equal and the numerical value is the maximum, the average value of the longitude and latitude of the point having the maximum correction vector product and the longitude and latitude of the low vortex extreme point O is calculated, and the point is recorded as the low vortex center W. In FIG. 20, C_rA、C_rC、C_rEAnd calculating the longitude and latitude average value of O, A, C, E points, and marking the obtained point as the low vortex center W to finish the positioning of the low vortex center. Longitude of the center of the low vortex is denoted as W_xLatitude is recorded as W_y。W_xAnd W_yThe calculation formula of (2) is as follows:

the position of the low vortex center W point is the corrected low vortex center, which is the object of the invention, and the whole correction steps are completed.

As shown in fig. 21, the cross point is the corrected vorticity center, the square point is the low vortex limit point, and the dot is the geometric center of the low vortex. The embodiment shows that the low vortex center is corrected by utilizing the wind field, the correction purpose is achieved, the corrected low vortex center is not located on a data point but is close to the center of the atmospheric vortex motion, and the correction effect is better as the data resolution is higher.

Through the design, the problem that the accurate position of the low vortex center cannot be automatically corrected in the high-altitude isobaric surface is solved, the analysis efficiency and the positioning precision are improved, and a solid foundation is laid for realizing precise and accurate automatic analysis and prediction.

Claims

1. A method for correcting the central position of low vortex by using wind field data is characterized by comprising the following steps:

s3, traversing the closed contour line and selecting a low vortex area;

s6, calculating the average position of a plurality of data points with the maximum vortex value at the same time, recording the average position as a low vortex center, and finishing correction of the low vortex center position;

2. The method for rectifying the low vortex center position by using the wind farm data as claimed in claim 1, wherein the condition satisfied by the closed contour line in the step S2 is as follows:

x₀≠lon_min∧x₀≠lon_max∧x_n≠lon_min∧x_n≠lon_max∧y₀≠lat_min∧y₀≠lat_max∧y_n≠lat_min∧y_n≠lat_max

3. The method for rectifying the central position of low vortex by using wind farm data as claimed in claim 1, wherein the step S3 comprises the steps of:

s301, searching potential height data points from bottom to top and from left to right in a closed contour range, and marking the first searched data point as an M point;

4. The method for rectifying the central position of low vortex by using wind farm data as claimed in claim 1, wherein the step S4 comprises the steps of:

s402, judging the nesting relation of any two marked closed contour lines;

5. The method for rectifying the central position of low vortex by using wind farm data as claimed in claim 4, wherein the step S402 comprises the steps of:

S4022, judging the closed contour L after any two marks_iAnd L_jWhether or not X is satisfied_imax>X_jmax∧X_imin<X_jmin∧Y_imax>Y_jmax∧Y_imin<Y_jminIf so, the contour L is closed_jIs a closed contour line L_iCompleting the judgment of the nesting relation, otherwiseReturning to step S4021, wherein X_imaxAnd X_jmaxRespectively represent a closed contour line L_iAnd L_jMost eastern point of (1), X_iminAnd X_jminRespectively represent a closed contour line L_iAnd L_jMost west of (1), Y_imaxAnd Y_jmaxRespectively represent a closed contour line L_iAnd L_jThe most northern point of (A), Y_jmaxAnd Y_jminRespectively represent a closed contour line L_jAnd L_jThe south-most point of (c).

6. The method for rectifying the central position of low vortex by using wind farm data as claimed in claim 1, wherein the step S5 comprises the steps of:

the expression for the vorticity value is as follows:

7. The method for rectifying the central position of low vortex by using wind farm data as claimed in claim 1, wherein the step S8 comprises the steps of:

8. The method for rectifying the central position of low vortex by using wind farm data as claimed in claim 7, wherein the expression of the vortex value in the step S802 is as follows:

9. The method for correcting the central position of the low vortex by using the wind farm data as claimed in claim 7, wherein the expression of the modified vector product in the step S804 is as follows:

10. The method for correcting the position of the low vortex center by using the wind farm data as claimed in claim 7, wherein the longitude and latitude expression of the low vortex center in step S805 or step S806 is as follows: