Typhoon center positioning method, device and equipment based on SAR satellite

Abstract

The invention discloses a typhoon center positioning method, device and equipment based on an SAR (Synthetic Aperture Radar) satellite, relates to the technical field of ocean microwave remote sensing, and is used for solving the problems that a typhoon positioning method in the prior art cannot accurately extract the position of a typhoon center and the positioning accuracy of the typhoon center is low. Comprising the following steps: acquiring basic data of an SAR satellite according to typhoon path information; performing sea surface wind speed and wind direction inversion based on the basic data to obtain inversion data; according to the inversion data, a gradient wind equation, a wind profile equation and the maximum wind speed are adopted to determine a high-wind-speed area of the typhoon; according to a cyclonic vortex structure of the typhoon, based on the vertical vortex field of the high-wind-speed area, the horizontal divergence field of the high-wind-speed area and the composite field of the high-wind-speed area, determining the position range of the center point of the typhoon; and positioning a typhoon center meeting preset precision according to the typhoon center point position range. According to the technical scheme, the positioning precision of the typhoon center can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of marine microwave remote sensing, and particularly to a typhoon center positioning method, device and equipment based on SAR satellites. Background Art

[0002] A typhoon is a special case of tropical cyclones. The arrival of a typhoon is often accompanied by rainfall, which is one of the sources of rainfall in coastal areas of our country. At the same time, the natural disasters brought by it are inevitable. The identification of typhoons and the determination of the typhoon center position are of extremely important significance for typhoon prediction and weather research, while the detection methods of typhoons are limited.

[0003] Traditional typhoon positioning methods include visual estimation method, cloud map center positioning method, physical model method and image processing method. Visual estimation method: In the early stage, the typhoon center positioning was mainly carried out by forecasters based on satellite cloud maps and other materials. There are problems such as long positioning time, insufficient stability and consistency, and it is difficult to accurately judge the typhoon center position due to factors such as the undulating cloud top, solar altitude angle, and asymmetric cloud system. Cloud map center positioning method: Using the detection data of geostationary or polar-orbiting meteorological satellites to analyze features such as brightness temperature to find the typhoon center. However, when the typhoon position changes or the cloud system features are not typical, the brightness temperature features may not be obvious, affecting the positioning accuracy. Physical model method: Based on physical models such as typhoon flow fields, methods such as the least squares method are used to solve the typhoon center position. However, the actual typhoon flow field may not conform to the assumed spiral flow field model, resulting in a large deviation in the positioning result. Image processing method: Processing images such as satellite cloud maps, such as using cloud edge detection, fitting, etc. to determine the typhoon center; but this method has a large amount of calculation, high requirements for image quality, and it is difficult to process dynamic typhoon cloud maps in real time.

[0004] Typhoons are sudden, and the disasters such as strong winds, heavy rains, and storm surges caused by them pose a serious threat to industrial and agricultural production, transportation and the safety of people's lives and property. Accurately and timely positioning the typhoon center position is crucial for accurate typhoon forecasting and disaster prevention and mitigation decision-making. And the cloud system structure is complex and changeable, and the cloud system structures of typhoons with different intensities and different development stages vary greatly. For example, some typhoons have a clear eye area, while some do not, and the cloud system is constantly changing, making it face many difficulties to use cloud system features for positioning. Especially for the on-site observation of typhoons at sea, remote sensing satellites have become the main means of observation. SAR satellites have high spatial resolution and time resolution and are an important means for detecting typhoons.

[0005] The typhoon positioning methods in the prior art cannot accurately extract the typhoon center position, and the positioning accuracy of the typhoon center is low. Therefore, there is an urgent need to provide a more reliable typhoon center positioning scheme based on SAR satellites. Summary of the Invention

[0006] The object of the present invention is to provide a typhoon center positioning method, device and equipment based on SAR satellites, which are used to solve the problem that the typhoon positioning method in the prior art cannot accurately extract the position of the typhoon center and the positioning accuracy of the typhoon center is low.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: In the first aspect, the present invention provides a typhoon center positioning method based on SAR satellites, and the method includes: Obtaining the basic data of the SAR satellite according to the typhoon path information; the basic data at least includes SAR satellite data and auxiliary data; the auxiliary data at least includes wind field auxiliary data and sea ice edge line auxiliary data; Inverting the sea surface wind speed and direction based on the basic data to obtain inversion data; According to the inversion data, using the gradient wind equation, the wind profile equation and the maximum wind speed to determine the high wind speed area of the typhoon; According to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, the horizontal divergence field and the composite field of the high wind speed area of the typhoon, determining the position range of the typhoon center point; Positioning the typhoon center that meets the preset accuracy according to the position range of the typhoon center point.

[0008] Optionally, inverting the sea surface wind speed and direction based on the basic data to obtain inversion data, including: Performing image preprocessing on the SAR satellite data, calculating and dividing the wind field units according to the requirements of the wind field unit division of sea surface wind field products with different resolutions; Using the sea ice edge line auxiliary data to perform sea ice identification on the divided wind units; Using the geophysical model function to perform co-polarization wind speed inversion and cross-polarization wind speed inversion on the sea surface wind field speed and direction; Then, according to the reference wind direction of the wind unit obtained from the numerical model wind field data, eliminating the wind direction ambiguity of the SAR sea surface wind field inversion result to obtain the inversion data that meets the requirements.

[0009] Optionally, using the geophysical model function to perform co-polarization wind speed inversion and cross-polarization wind speed inversion on the sea surface wind field speed and direction, including: When the wind speed is less than the preset threshold, using the sea surface wind direction and the observation geometry data, and selecting the CMOD model of the GMF geophysical model function to perform the inversion of the sea surface wind speed. The CMOD model is a function model of the sea surface wind speed, the sea surface wind direction and the radar incident angle, and the CMOD model is expressed as: ; Wherein, is the backscattering coefficient, represents the relative wind direction, represents the empirical parameters, where B0, B1, and B2 are functions of the sea surface wind speed and the incident angle, and are all constants; When the wind speed is greater than or equal to the preset threshold, the formula is used: ; The sea surface wind speed is retrieved using the linear relationship model between the cross-polarized backscattering coefficient and the sea surface wind speed, where U is the sea surface wind speed, and a and b are the fitting coefficients of the linear relationship.

[0010] Optionally, according to the retrieved data, the high wind speed region of the typhoon is determined using the gradient wind equation, the wind profile equation, and the maximum wind speed, including: According to the retrieved data, the gradient wind equation is used: ; Determine the radial range of the high wind speed region; where, is the radial wind, w is the vertical velocity, r is the radial coordinate, z is the vertical coordinate, v is the horizontal velocity component, the meridional velocity component of the gradient wind, f is the Coriolis parameter, represents the shear stress between the z direction and the r direction, is the fluid density, the remaining external forces in the horizontal direction; The wind profile equation is used: ; Determine the distribution range of the high wind speed region in the vertical direction; where, represents the characteristic wind speed, represents the maximum wind speed, is the air density, is the base of the natural logarithm function, r is the distance from the observation point to the center of the cyclone, RMW is the radius of the maximum wind speed, B is the proportionality coefficient, and P is the pressure; Determine the position of the maximum wind speed. Taking the position of the maximum wind speed as the center, estimate the horizontal range of the high wind speed region according to the size characteristics and the wind field structure characteristics of the typhoon, and combine the actual wind speed observation data to adjust the horizontal range of the high wind speed region to obtain the typhoon high wind speed region that meets the conditions.

[0011] Optionally, according to the cyclonic vortex structure of the typhoon, determine the range of the typhoon center point according to the vertical vorticity field, the horizontal divergence field, and the composite field of the high wind speed region, including: The formula is used: ; Calculate the absolute vorticity of the vorticity field, where, is the absolute vorticity, is the relative vorticity, is the planetary vorticity; Adopt the formula: ; Calculate the relative vorticity of the vorticity field, where is the three-dimensional wind vector, and obtain: ; The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as: ; The difference form expression of the vertical component of the relative vorticity of the vorticity field is: ; The differential expression of the horizontal divergence of the divergence field is: ; The difference form expression of the horizontal divergence of the divergence field is: ; Determine the product of the vorticity field and the divergence field as the composite field; According to the vorticity field, the divergence field and the composite field, determine the longitude and latitude and wind speed corresponding to the positive maximum value of the vorticity field in the high wind speed area, the longitude and latitude and wind speed corresponding to the negative minimum value of the divergence field, and the longitude and latitude and wind speed corresponding to the negative minimum value of the composite field, and obtain the longitude and latitude and wind speed of the wind direction rotation center point, the wind direction convergence center point, and the wind direction composite field center point; Determine the position of the center point with the minimum wind speed among the three center points as the potential center point, and determine the longitude and latitude range of ±0.5° near the potential center point as the typhoon center point position range.

[0012] Optionally, locating the typhoon center that meets the preset accuracy according to the typhoon center point position range includes: Search for the point with the minimum wind speed within the typhoon center point position range; Select different search sizes according to the different sizes of the wind field resolution. For a low-resolution wind field, sort the wind speeds of each wind vector unit in the area near the typhoon center from small to large with the first search size, and record the longitude and latitude positions corresponding to the wind speeds at the same time, and select the point with the minimum wind speed as the typhoon center; For a high-resolution wind field, slide and calculate the average wind speed within each search size in the area near the typhoon center with the second search size: ; Among them, the second search size is greater than the first search size, k is the window size, x and y are the indices of matrix A near the typhoon center, and i and j are the indices of the output matrix B. By recording the longitude and latitude of the starting grid point, the values in the average wind speed matrix B within the region are sorted to determine the grid point with the minimum average wind speed and the corresponding longitude and latitude, and the grid point with the minimum average wind speed is determined as the typhoon center point.

[0013] Optionally, the method further includes: Calculating the radius of the wind circle; The calculation of the radius of the wind circle includes: Based on the distribution characteristics of wind speed with radius, combining the wind speed thresholds in different regions of the typhoon to divide the range of the wind circle; According to the longitude and latitude of the typhoon center point, the maximum wind speed, and the radius of the maximum wind speed, calculate the parameter B of the Holland model: ; The wind speed profile model is expressed as: ; Among them, the longitude and latitude are (lat0, lon0), vamx represents the maximum wind speed, RMW represents the radius of the maximum wind speed, the radius of the maximum wind speed is the distance between the maximum wind speed wind unit and the typhoon center, vmax is the maximum wind speed, and the maximum wind speed is the maximum wind speed with the typhoon center as the origin and within a preset radius; Taking the typhoon center point as the origin, dividing the wind speed into four quadrants, respectively calculating the wind speeds of the observation points within different radii from the typhoon center point to form the typhoon radial wind speed profile, and obtaining the size of the wind circle radius of each quadrant.

[0014] Compared with the prior art, a typhoon center positioning method based on SAR satellites provided by the present invention obtains the basic data of the SAR satellite according to the typhoon path information; performs sea surface wind speed and direction inversion based on the basic data to obtain the inversion data; according to the inversion data, uses the gradient wind equation, the wind profile equation, and the maximum wind speed to determine the high wind speed area of the typhoon; according to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, the horizontal divergence field, and the composite field of the high wind speed area, determines the position range of the typhoon center point; locates the typhoon center that meets the preset accuracy according to the position range of the typhoon center point. Using high-resolution SAR satellite data for typhoon center positioning, the typhoon structure is clearer and the center positioning accuracy is higher. The wind field inverted from SAR data comprehensively considers multiple characteristics of the typhoon to accurately extract the typhoon center position, improves the typhoon center positioning accuracy, realizes accurate typhoon center positioning and the calculation of complete elements such as the maximum average wind speed and the wind circle radius, improves the typhoon forecasting and real-time monitoring capabilities, and can reduce the losses caused by typhoons to a certain extent.

[0015] Second aspect, the present invention provides a typhoon center positioning device based on SAR satellites, the device comprising: A basic data determination module, configured to obtain basic data of the SAR satellite according to typhoon path information; the basic data at least includes SAR satellite data and auxiliary data; the auxiliary data at least includes wind field auxiliary data and sea ice edge line auxiliary data; A sea surface wind speed and direction inversion module, configured to perform sea surface wind speed and direction inversion based on the basic data to obtain inversion data; A typhoon high wind speed area determination module, configured to determine the high wind speed area of the typhoon according to the inversion data by using the gradient wind equation, the wind profile equation, and the maximum wind speed; A typhoon center point position range determination module, configured to determine the typhoon center point position range according to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, the horizontal divergence field, and the composite field of the high wind speed area; A typhoon center determination module, configured to locate the typhoon center that meets the preset accuracy according to the typhoon center point position range.

[0016] Third aspect, the present invention provides a typhoon center positioning device based on SAR satellites, the device comprising: A memory, a processor, and a communication interface coupled to the processor; a computer program executable by the processor is stored on the memory; when the processor runs the computer program, it executes the above typhoon center positioning method.

[0017] Fourth aspect, the present invention provides a computer storage medium, wherein instructions are stored in the computer storage medium, and when the instructions are run, the above typhoon center positioning method is implemented.

[0018] The technical effects achieved by the device type solution provided in the second aspect, the device type solution provided in the third aspect, and the computer storage medium solution provided in the fourth aspect are the same as those of the method type solution provided in the first aspect, and will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 It is a schematic flowchart of a typhoon center positioning method based on SAR satellites; Figure 2 It is an overall flowchart of a typhoon center positioning method based on SAR satellites; Figure 3 It is a schematic structural diagram of a typhoon center positioning device based on SAR satellites; Figure 4 It is a schematic structural diagram of a typhoon center positioning device based on a SAR satellite. Specific implementation manners

[0020] For the convenience of clearly describing the technical solutions of the embodiments of the present invention, in the embodiments of the present invention, terms such as "first" and "second" are used to distinguish the same items or similar items with basically the same functions and roles. For example, the first threshold and the second threshold are only used to distinguish different thresholds, and do not limit their sequence. Those skilled in the art can understand that the terms such as "first" and "second" do not limit the quantity and execution order, and the terms such as "first" and "second" do not necessarily limit to be different.

[0021] It should be noted that in the present invention, words such as "exemplary" or "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the present invention should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly speaking, using words such as "exemplary" or "for example" aims to present relevant concepts in a specific manner.

[0022] In the present invention, "at least one" means one or more, and "a plurality" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone, where A and B can be singular or plural. The character " / " generally represents an "or" relationship between the front and rear associated objects. "At least one (item)" or its similar expression below refers to any combination of these items, including any combination of single item (item) or plural items (items). For example, at least one (item) of a, b or c can represent: a, b, c, the combination of a and b, the combination of a and c, the combination of b and c, or the combination of a, b and c, where a, b and c can be single or multiple.

[0023] In the prior art, the positioning means of the typhoon center are all based on the inversion of the wind field by a scatterometer, and the process is to first determine the maximum wind speed area, and then determine the wind vorticity and divergence, with poor accuracy. Typhoon is one of the severe natural disaster weather. Accurately positioning the typhoon center has important reference and application significance for typhoon forecasting and monitoring, and at the same time has certain guiding significance for regional and even global weather and climate research. And it is difficult to accurately and completely calculate elements such as the position of the typhoon center with conventional statistical data and observational data. On the basis of the prior art, this solution further optimizes the specific algorithm for wind speed screening, the calculation methods of vorticity and divergence, the determination method of the typhoon center position range, the typhoon center calculation method and other details, so that it has a significant improvement in positioning accuracy, efficiency and other aspects.

[0024] The present invention uses high - resolution SAR satellite data for typhoon center positioning. The typhoon structure is clearer and the center positioning accuracy is higher. The typhoon center is roughly extracted according to the wind field retrieved from SAR data, comprehensively considering the high - wind - speed characteristics, vorticity and curl characteristics, and composite - field characteristics of the typhoon. The average wind speed is searched and calculated using the result of the rough extraction, and an improved scheme is adopted to determine the position range of the typhoon center point and calculate the typhoon center. Specifically, according to the retrieved data, the high - wind - speed region of the typhoon is determined by using the gradient - wind equation, wind - profile equation and maximum wind speed; according to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, horizontal divergence field and composite field in the high - wind - speed region, the position range of the typhoon center point is determined, and then the typhoon center is further calculated, so that the accurate extraction of the typhoon center position can be carried out, improving the positioning accuracy of the typhoon center. Next, the solution provided in the embodiments of this specification will be described in conjunction with the accompanying drawings: As Figure 1 shown, the process may include the following steps: Step 110: Obtain the basic data of the SAR satellite according to the typhoon path information.

[0025] The basic data includes at least SAR satellite data and auxiliary data; the auxiliary data includes at least wind - field auxiliary data and sea - ice edge - line auxiliary data.

[0026] Obtain the typhoon path information, SAR observation data, ERA5 wind - field auxiliary data, and sea - ice edge - line auxiliary data released by a reliable institution. Specifically, in combination with the typhoon path information, determine the time period and spatial range affected by the typhoon, and then screen out the SAR satellite data obtained within this time period and region from the data sources. For example, if a typhoon passes through a certain sea area on a certain day, select the satellite's observation data of this sea area for a period of time before and after the typhoon passes. The obtained original SAR satellite data can be pre - processed, such as radiometric calibration, geometric correction, and noise removal, to improve the data quality and usability. Radiometric calibration can convert digital signals into physical quantities, geometric correction can correct the geometric deformation of the image, and noise removal can remove the interference signals in the image.

[0027] The wind - field auxiliary data may include re - analysis data, which integrates a variety of observational data and numerical models, and has high spatio - temporal resolution and good data quality. Such as ERA5 re - analysis data, which provides global atmospheric parameters, including wind - field data, and the wind - field data corresponding to the time and space can be selected as auxiliary according to the typhoon path.

[0028] In the auxiliary data of the sea ice edge line, generally, the isoline where the sea ice concentration reaches a certain threshold (such as 15%) is regarded as the sea ice edge line. In the case where the sea ice edge is relatively clear and the cloud cover is less, optical satellite remote sensing data can be used to extract the sea ice edge line. For example, for MODIS satellite data, by processing and analyzing the images in the visible and infrared bands, the boundary between sea ice and open water is identified, thereby obtaining the sea ice edge line information. These in-situ observation data can be used to verify and calibrate the sea ice edge line retrieved by satellite remote sensing, especially for the determination of some complex sea ice forms and edge regions, which is of great significance.

[0029] Step 120: Based on the basic data, perform sea surface wind speed and direction inversion to obtain inversion data.

[0030] The sea surface wind speed and direction inversion includes co-polarization wind speed inversion and cross-polarization wind speed inversion.

[0031] Step 130: According to the inversion data, use the gradient wind equation, wind profile equation, and maximum wind speed to determine the high wind speed area of the typhoon.

[0032] The gradient wind is the actual wind on the ground or at sea, which is in balance with the horizontal pressure gradient force, Coriolis force, and inertial centrifugal force. In a low-pressure system such as a typhoon, the gradient wind equation can better describe the relationship between wind speed and pressure field. Using the pressure field data in the typhoon area retrieved by SAR satellite, the pressure gradient can be calculated. Combining known Coriolis parameters (determined by the latitude) and parameters such as air density, substituting them into the gradient wind equation, the wind speeds at different positions can be solved.

[0033] The wind profile equation describes the law of wind speed variation with height. Under different atmospheric stability conditions, the form of the wind profile equation is different. Common ones include the logarithmic wind profile equation, etc. Using the wind speed data near the sea surface obtained by SAR satellite, combined with local atmospheric stability conditions and surface roughness length and other parameters, the wind speeds at different heights are calculated upward using the wind profile equation.

[0034] In this solution, the radial range of the high wind speed area is determined using the gradient wind equation, and the distribution range of the high wind speed area in the vertical direction is determined using the wind profile equation.

[0035] Step 140: According to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, horizontal divergence field, and composite field of the high wind speed area, determine the position range of the typhoon center point.

[0036] According to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, horizontal divergence field, and composite field of the high wind speed area, determine the position range of the typhoon center point, and further calculate the typhoon center.

[0037] Step 150: Locate the typhoon center that meets the preset accuracy according to the position range of the typhoon center point.

[0038] Step 140 can only determine the range of the typhoon center point position. If you want to locate the accurate typhoon center, you also need to further adopt the improved solution of the present invention to determine the grid point with the minimum average wind speed and the corresponding longitude and latitude, and use this point as the wind speed center, that is, the final typhoon center point.

[0039] Figure 1 In the method, obtain the basic data of the SAR satellite according to the typhoon path information; perform sea surface wind speed and direction inversion based on the basic data to obtain inversion data; according to the inversion data, use the gradient wind equation, wind profile equation and maximum wind speed to determine the high wind speed area of the typhoon; according to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, horizontal divergence field and composite field of the high wind speed area, determine the position range of the typhoon center point; locate the typhoon center that meets the preset accuracy according to the position range of the typhoon center point. Using high-resolution SAR satellite data for typhoon center location, the typhoon structure is clearer and the center location accuracy is higher. The wind field inverted from SAR data comprehensively considers multiple characteristics of the typhoon to accurately extract the typhoon center position, improves the typhoon center location accuracy, realizes accurate typhoon center location and calculation of complete elements such as maximum average wind speed and wind circle radius, improves the typhoon forecast and real-time monitoring capabilities, and can reduce the losses caused by typhoons to a certain extent.

[0040] Based on Figure 1 the method, the embodiments of the present specification also provide some specific implementation manners of this method, which will be described below.

[0041] Specifically, as Figure 2 shown, the present invention obtains the corresponding SAR satellite data through the typhoon path information released by a trusted institution, performs sea surface wind speed and direction inversion based on the SAR satellite data and other auxiliary data; screens the position of the typhoon high wind area according to the sea surface wind speed; according to the cyclonic vortex structure of the typhoon, calculates and establishes the vertical vorticity field, horizontal divergence field and composite field of the high wind speed area, and respectively performs center position calculation and minimum wind speed calculation to determine the potential typhoon center point position; searches and calculates the average wind speed in the vicinity of the potential typhoon center point, selects the point with the minimum wind speed as the typhoon center, and calculates the typhoon wind circle radius according to the typhoon center position; evaluates the positioning accuracy of the typhoon center position. The typhoon center position can be accurately extracted, and the typhoon center positioning accuracy is improved. Next, further description will be made on the specific implementation means of the process steps provided by the present invention: Step 120, in specific implementation, may include: Perform image preprocessing on the SAR satellite data, calculate and divide the wind field units according to the requirements of wind field unit division for sea surface wind field products with different resolutions. Use the sea ice edge line auxiliary data to identify sea ice for the divided wind units. Use the geophysical model function to perform co-polarized wind speed inversion and cross-polarized wind speed inversion for the sea surface wind field speed and direction. Then, according to the reference wind direction of the wind units obtained from the numerical model wind field data, eliminate the wind direction ambiguity of the SAR sea surface wind field inversion result to obtain the inversion data that meets the requirements.

[0042] Furthermore, perform image preprocessing on the SAR observation image of the sea surface wind field inversion. Then, according to the requirements of wind field unit division for sea surface wind field products with different resolutions, calculate and divide the wind field units. Use the sea ice edge line auxiliary data to identify sea ice for the wind units. Use the geophysical model function to realize the inversion of parameters such as the sea surface wind field speed and direction. Then, according to the reference wind direction of the wind units obtained from the numerical model wind field data, eliminate the wind direction ambiguity of the SAR sea surface wind field inversion result.

[0043] When the wind speed is less than the preset threshold, use the sea surface wind direction and observation geometry data, and select the CMOD model of the GMF geophysical model function to perform the inversion of the sea surface wind speed. The CMOD model is a function model of the sea surface wind speed, sea surface wind direction, and radar incident angle.

[0044] Since the co-polarization will reach saturation when the wind speed is about greater than 25 m / s at higher wind speeds, which limits its application in extreme high wind speed conditions, the linear relationship model between the cross-polarized backscattering coefficient and the sea surface wind speed is used to perform the inversion of the sea surface wind speed under hurricane or typhoon conditions. Therefore, when the wind speed is greater than or equal to the preset threshold, the linear relationship model between the cross-polarized backscattering coefficient and the sea surface wind speed is used to perform the inversion of the sea surface wind speed.

[0045] Specifically, the CMOD model is a function model of the sea surface wind speed, sea surface wind direction, and radar incident angle, and the CMOD model is expressed as formula (1): (1) Where is the backscattering coefficient, represents the relative wind direction, that is, the angle between the sea surface wind direction and the radar beam azimuth direction (0°~360°), represents the empirical parameter, B0, B1, and B2 are functions of the sea surface wind speed and incident angle, and are all constants; When the wind speed is greater than or equal to the preset threshold, use formula (2): (2) Retrieve the sea surface wind speed using the linear relationship model between the cross-polarization backscattering coefficient and the sea surface wind speed, where U is the sea surface wind speed, and both a and b are fitting coefficients of the linear relationship.

[0046] Step 130, when implemented, may include: Under normal circumstances, the typhoon structure can be divided into the typhoon eye region in the horizontal direction, where the wind speed in the typhoon eye region rapidly decreases or is calm, with an average diameter of about 45 km, the strong wind region, also known as the outer circle of the typhoon, with a diameter generally reaching 400 - 600 km, the peripheral wind force can reach 15 m / s, and the wind speed increases rapidly inward, and the typhoon vortex region, also known as the eyewall, which is the middle circle of the typhoon and also a band of maximum wind speed distributed around the typhoon, with an average width of 10 - 20 km, and is the region where the typhoon's destructive power is the most violent and concentrated.

[0047] The typhoon center is located in the typhoon eye region. In a fully developed strong cyclone, the wind force is the strongest and the air pressure is the lowest near the center. In a stable axisymmetric mode, the radial wind equation can be expressed in terms of the gradient tangential wind as formula (3): (3) Determine the radial range of the high wind speed region; where, is the radial wind, w is the vertical velocity, r is the radial coordinate, z is the vertical coordinate, v is the horizontal velocity component, is the meridional velocity component of the gradient wind, f is the Coriolis parameter, represents the shear stress between the z direction and the r direction, is the fluid density, the remaining external forces in the horizontal direction; Adopt the wind profile equation, such as formula set (4): (4) Determine the vertical distribution range of the high wind speed region; where, represents the characteristic wind speed, represents the maximum wind speed, is the air density, is the base of the natural logarithm function, r is the distance from the observation point to the cyclone center, RMW is the radius of maximum wind speed, B is the proportionality coefficient, and P is the pressure; Determine the position of the maximum wind speed. Centered on the position of the maximum wind speed, estimate the horizontal range of the high wind speed area according to the size characteristics and wind field structure characteristics of the typhoon, and combine with the actual wind speed observation data to adjust the horizontal range of the high wind speed area to obtain a typhoon high wind speed area that meets the conditions. Generally, wind speeds of 17 m / s, 26 m / s, and 34 m / s are used to characterize three different typhoon intensities: strong wind, destructive wind, and hurricane. Generally, 17 m / s is set as the high wind speed search threshold, and the observation area with a wind speed greater than 17 m / s is searched as the high wind speed area.

[0048] Since extreme points of the composite field value also appear in non-typhoon structure areas, which is related to the development stage and intensity of the typhoon. During the formation and development of the typhoon, the typhoon structure is not complete, and there is no obvious eye profile and solid cloud wall. Therefore, a high wind speed threshold is needed to limit the general range of the typhoon structure area in order to more accurately locate the typhoon center.

[0049] Step 140, in specific implementation, may include: Adopt formula (5): (5) Calculate the absolute vorticity of the vorticity field, where, is the absolute vorticity, is the relative vorticity, is the planetary vorticity; Adopt formula (6): (6) Calculate the relative vorticity of the vorticity field, where, is the three-dimensional wind vector, and formula (7) is obtained: (7) The sea surface wind field passed by the typhoon has an obvious cyclonic vortex structure and is often accompanied by severe weather such as strong winds and heavy rains. Vorticity represents the rotational characteristics of atmospheric motion. Due to the nearly horizontal motion of the atmosphere, generally only the vertical component of the relative vorticity is considered. Due to the Coriolis force, in the Northern Hemisphere, the wind field converges counterclockwise towards the typhoon center, rotates counterclockwise in the Southern Hemisphere, and there should be a local maximum point at the typhoon center. The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as formula (8): (8) The difference form expression of the vertical component of the relative vorticity of the vorticity field is formula (9): (9) Due to the nearly horizontal movement of the atmosphere, only the horizontal divergence of the atmospheric movement is considered. According to the structural characteristics of the typhoon, the divergence field at the typhoon center position should be negative and only at the center can there be a local minimum point. The differential expression of the horizontal divergence of the divergence field is formula (10): (10) The difference form expression of the horizontal divergence of the divergence field is formula (11): (11) Determine the product of the vorticity field and the divergence field as the composite field; the composite field not only considers the characteristics of the vorticity field but also the characteristics of the divergence field. Theoretically, the composite field within the high wind speed range of the typhoon is negative, and there is a minimum point at the typhoon center. The magnitude of the composite field can be calculated by for calculation.

[0050] According to the vorticity field, the divergence field, and the composite field, determine the longitude and latitude and wind speed corresponding to the positive maximum value of the vorticity field in the high wind speed region, the longitude and latitude and wind speed corresponding to the negative minimum value of the divergence field, and the longitude and latitude and wind speed corresponding to the negative minimum value of the composite field, so as to obtain the longitude and latitude and wind speed of the wind direction rotation center point, the wind direction convergence center point, and the wind direction composite field center point; Determine the center point position with the minimum wind speed among the three center points as the potential center point, and determine the longitude and latitude range of ±0.5° near the potential center point as the typhoon center point position range.

[0051] According to the vorticity field, divergence field, and composite field calculated above, find the longitude and latitude and wind speed corresponding to the positive maximum value of the vorticity field in the high wind speed region, the longitude and latitude and wind speed corresponding to the negative minimum value of the divergence field, and the longitude and latitude and wind speed corresponding to the negative minimum value of the composite field, so as to obtain the longitude and latitude and wind speed of the three center points. The three center points respectively represent the wind direction rotation center point, the wind direction convergence center point, and the wind direction composite field center point. Also, the wind speed of the typhoon center point should be the minimum. Therefore, select the center point position with the minimum wind speed among the three center points as the potential center point. This potential center point can be called the wind direction center point, and the wind direction center point is not necessarily the real typhoon center point. The real typhoon center point should still be the point with the minimum wind speed in the area near the typhoon. Therefore, with the wind direction center point as the center, search for the point with the minimum wind speed in its nearby area. Here, select the longitude and latitude range of ±0.5° near the potential center point as the area near the typhoon center point.

[0052] Step 150, the specific implementation process may include: Search for the point with the minimum wind speed within the typhoon center point position range; Select different search sizes according to the size of the wind field resolution. For a low-resolution wind field, sort the wind speeds of each wind vector unit in the area near the typhoon center from small to large according to the first search size, and record the corresponding longitude and latitude positions of the wind speeds at the same time. Select the point with the minimum wind speed as the typhoon center. For a high-resolution wind field, calculate the average wind speed within each search size in the area near the typhoon center by sliding with the second search size, as shown in formula (12): (12) Among them, the second search size is larger than the first search size, k is the window size, x and y are the indexes of matrix A near the typhoon center, and i and j are the indexes of output matrix B. By recording the longitude and latitude of the starting grid point, sort the values in the average wind speed matrix B in the area, determine the grid point with the minimum average wind speed and the corresponding longitude and latitude, and determine the grid point with the minimum average wind speed as the typhoon center point.

[0053] More specifically, since the typhoon wind direction often comes from numerical model information, there are often large deviations in the determined typhoon center position. Therefore, find the point with the minimum wind speed in the area (±0.5°) near the typhoon center point determined above. Different search sizes can be selected according to the size of the wind field resolution. For a low-resolution wind field, for example: a 1×1 search size can be used, that is, sort the wind speeds of each wind vector unit in the area near the typhoon center from small to large, and record the corresponding longitude and latitude positions of the wind speeds at the same time. Select the point with the minimum wind speed as the typhoon center; for a high-resolution wind field, the search size can be increased, such as: using 2×2 and 3×3 as the search sizes, and sliding to calculate the average wind speed within each search size in the area near the typhoon center.

[0054] In addition, for the technical solution provided by the present invention, it is also necessary to further calculate the radius of the wind circle. The method for delimiting the wind circle of the typhoon radial average wind speed profile is usually based on the distribution characteristics of the wind speed with the radius, and combines the wind speed thresholds in different areas of the typhoon to delimit the wind circle range. Let the longitude and latitude of the typhoon center point obtained in (five) be (lat0, lon0), the maximum wind speed be vamx, and the radius of the maximum wind speed be RMW. Calculate the parameter B of the Holland model, as shown in formula (13): (13) The wind speed profile model is expressed as formula (14): (14) The maximum wind speed vmax is set as the maximum wind speed within a radius of 100 km with the typhoon center as the origin, and RMW is the distance between the maximum wind speed wind unit and the typhoon center.

[0055] According to the model, with the typhoon center point as the origin, the wind speed is divided into four quadrants, and the wind speeds of the observation points within different radii r from the center point are calculated respectively to form the typhoon radial wind speed profile. After reaching the maximum wind speed, the r value corresponding to the attenuation to 17.2 m / s is defined as the radius of the 7-level wind circle, and the attenuation to 24.5 m / s is defined as the radius of the 10-level wind circle, and the wind circle radius sizes of each quadrant are obtained.

[0056] Further, in order to verify the accuracy of typhoon center positioning, the typhoon center point obtained by the foregoing solution is compared with the CMA best track dataset of a reliable institution. The best track dataset includes typhoon time, typhoon intensity, typhoon center longitude and latitude, typhoon center minimum air pressure, 2-minute average near-center maximum wind speed, and 2-minute average wind speed (m / s). The average deviation and root mean square error of the meridional, zonal, and total meridional and zonal distances between the located typhoon center position and the CMA center position are statistically used as typhoon center positioning indicators.

[0057] Based on the same idea, the present invention also provides a typhoon center positioning device based on SAR satellites, as Figure 3 shown, the device may include: A basic data determination module 310, configured to obtain the basic data of the SAR satellite according to the typhoon path information; the basic data at least includes SAR satellite data and auxiliary data; the auxiliary data at least includes wind field auxiliary data and sea ice edge line auxiliary data; A sea surface wind speed and direction inversion module 320, configured to perform sea surface wind speed and direction inversion based on the basic data to obtain inversion data; A typhoon high wind speed area determination module 330, configured to determine the high wind speed area of the typhoon according to the inversion data by using the gradient wind equation, the wind profile equation, and the maximum wind speed; A typhoon center point position range determination module 340, configured to determine the typhoon center point position range according to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, the horizontal divergence field, and the composite field of the high wind speed area of the typhoon; A typhoon center determination module 350, configured to locate the typhoon center that meets the preset accuracy according to the typhoon center point position range.

[0058] Based on Figure 3 the device in, some specific implementation units may also be included: Optionally, the sea surface wind speed and direction inversion module 320 may include: A wind field division unit, configured to perform image preprocessing on the SAR satellite data, calculate and divide the wind field units according to the requirements of wind field unit division of sea surface wind field products with different resolutions; An ice identification unit, which is used to identify sea ice for the divided wind units by using the auxiliary data of the sea ice edge line; An inversion unit, which is used to perform co-polarized wind speed inversion and cross-polarized wind speed inversion on the sea surface wind field speed and direction by using a geophysical model function; A rejection unit, which is used to then reject the wind direction ambiguity of the SAR sea surface wind field inversion result according to the reference wind direction of the wind unit obtained from the numerical model wind field data, so as to obtain the inversion data that meets the requirements.

[0059] Optionally, the inversion unit may include: A co-polarized wind speed inversion subunit, which is used to, when the wind speed is less than a preset threshold, use the sea surface wind direction and observation geometry data to select the CMOD model of the GMF geophysical model function to perform sea surface wind speed inversion. The CMOD model is a function model of sea surface wind speed, sea surface wind direction, and radar incident angle, and the CMOD model is expressed as: ; Wherein, is the backscattering coefficient, represents the relative wind direction, represents the empirical parameter, and B0, B1, and B2 are functions of sea surface wind speed and incident angle and are all constants; A cross-polarized wind speed inversion subunit, which is used to, when the wind speed is greater than or equal to the preset threshold, adopt the formula: ; Perform sea surface wind speed inversion by using the linear relationship model between the cross-polarized backscattering coefficient and the sea surface wind speed, where U is the sea surface wind speed, and a and b are both fitting coefficients of the linear relationship.

[0060] Optionally, the typhoon high wind speed area determination module 330 may include: A radial range determination unit for the high wind speed area, which is used to, according to the inversion data, adopt the gradient wind equation: ; Determine the radial range of the high wind speed area; wherein, is the radial wind, w is the vertical velocity, r is the radial coordinate, z is the vertical coordinate, v is the horizontal velocity component, the meridional velocity component of the gradient wind, f is the Coriolis parameter, represents the shear stress between the z direction and the r direction, is the fluid density, the remaining external forces in the horizontal direction; A vertical range determination unit for the high wind speed area, which is used to adopt the wind profile equation: ; Determine the distribution range of the high wind speed area in the vertical direction; wherein, represents the characteristic wind speed, represents the maximum wind speed, is the air density, is the base of the natural logarithm function, r is the distance from the observation point to the center of the cyclone, RMW is the radius of the maximum wind speed, B is the proportionality coefficient, and P is the pressure; The typhoon high wind speed area determination unit is used to determine the position of the maximum wind speed. Taking the position of the maximum wind speed as the center, estimate the horizontal range of the high wind speed area according to the size characteristics and wind field structure characteristics of the typhoon, and combine the actual wind speed observation data to adjust the horizontal range of the high wind speed area to obtain a typhoon high wind speed area that meets the conditions.

[0061] Optionally, the typhoon center point position range determination module 340 can be used for: Adopt the formula: ; Calculate the absolute vorticity of the vorticity field, where is the absolute vorticity, is the relative vorticity, is the planetary vorticity; Adopt the formula: ; Calculate the relative vorticity of the vorticity field, where is the three-dimensional wind vector, and obtain: ; The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as: ; The difference form expression of the vertical component of the relative vorticity of the vorticity field is: ; The differential expression of the horizontal divergence of the divergence field is: ; The difference form expression of the horizontal divergence of the divergence field is: ; Determine the product of the vorticity field and the divergence field as the composite field; According to the vorticity field, the divergence field and the composite field, determine the longitude and latitude and wind speed corresponding to the positive maximum value of the vorticity field of the high wind speed area, the longitude and latitude and wind speed corresponding to the negative minimum value of the divergence field, and the longitude and latitude and wind speed corresponding to the negative minimum value of the composite field, and obtain the longitude and latitude and wind speed of the wind direction rotation center point, the wind direction convergence center point, and the wind direction composite field center point; Determine the positions of the three central points with the minimum wind speeds as potential central points, and determine the range of the typhoon center position as the range of longitude and latitude within ±0.5° near the potential central points.

[0062] Optionally, the typhoon center determination module 350 can be used for: Search for the point with the minimum wind speed within the range of the typhoon center position; Select different search sizes according to the size of the wind field resolution. For a low-resolution wind field, sort the wind speeds of each wind vector unit in the area near the typhoon center from small to large with the first search size, and record the corresponding longitude and latitude positions of the wind speeds at the same time. Select the point with the minimum wind speed as the typhoon center; For a high-resolution wind field, calculate the average wind speed within each search size in the area near the typhoon center by sliding with the second search size: ; Among them, the second search size is greater than the first search size, k is the window size, x and y are the indices of matrix A near the typhoon center, i and j are the indices of the output matrix B. By recording the longitude and latitude of the starting grid point, sort the values in the average wind speed matrix B in the area to determine the grid point with the minimum average wind speed and the corresponding longitude and latitude, and determine the grid point with the minimum average wind speed as the typhoon center point.

[0063] Optionally, the method further includes: A wind circle radius calculation module for calculating the wind circle radius; The wind circle radius calculation module can be used for: Based on the distribution characteristics of the wind speed with respect to the radius, combine the wind speed thresholds in different regions of the typhoon to divide the wind circle range; According to the longitude and latitude of the typhoon center point, the maximum wind speed, and the radius of the maximum wind speed, calculate the parameter B of the Holland model: ; The wind speed profile model is expressed as: ; Among them, the longitude and latitude are (lat0, lon0), vamx represents the maximum wind speed, RMW represents the radius of the maximum wind speed, the radius of the maximum wind speed is the distance between the maximum wind speed wind unit and the typhoon center, vmax is the maximum wind speed, and the maximum wind speed is the maximum wind speed with the typhoon center as the origin and within the preset radius; With the typhoon center point as the origin, divide the wind speed into four quadrants, calculate the wind speeds of the observation points within different radii from the typhoon center point respectively, form the typhoon radial wind speed profile, and obtain the size of the wind circle radius of each quadrant.

[0064] Based on the same idea, the embodiments of this specification also provide a typhoon center positioning device based on SAR satellites. As Figure 4 shown, the device includes: A memory, a processor, and a communication interface coupled to the processor; a computer program that can be run by the processor is stored on the memory; when the processor runs the computer program, it executes the aforementioned typhoon center positioning method based on SAR satellites.

[0065] As Figure 4 shown, the above-mentioned processor can be a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits for controlling the execution of the program of the present invention. The above-mentioned communication interface can be one or more. The communication interface can use any transceiver-like device for communicating with other devices or communication networks.

[0066] As Figure 4 shown, the above-mentioned terminal device can also include a communication line. The communication line can include a path for transmitting information between the above-mentioned components.

[0067] Optionally, as Figure 4 shown, the above-mentioned terminal device can also include a memory. A computer program that can be run by the processor is stored on the memory; when the processor runs the computer program, the method provided by the embodiments of the present invention is implemented.

[0068] As Figure 4As shown in the figure, the memory may be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM), or other optical disc storage, optical disc storage (including compact discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media, or other magnetic storage devices, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory may exist independently and be connected to the processor through a communication line. The memory may also be integrated with the processor.

[0069] Optionally, the computer-executable instructions in the embodiments of the present invention may also be referred to as application program code, and the embodiments of the present invention do not make specific limitations thereto.

[0070] In a specific implementation, as an embodiment, as Figure 4 shown, the processor may include one or more CPUs, such as Figure 4 CPU0 and CPU1 in

[0071] In a specific implementation, as an embodiment, as Figure 4 shown, the terminal device may include multiple processors, such as Figure 4 the processors in

[0072] Based on the same concept, the embodiments of this specification also provide a computer storage medium corresponding to the above embodiments. Instructions are stored in the computer storage medium, and when the instructions are run, the methods in the above embodiments are implemented.

[0073] The above mainly introduces the solution provided by the embodiments of the present invention from the perspective of the interaction between various modules. It can be understood that, in order to implement the above functions, each module includes the corresponding hardware structure and / or software unit for executing each function. Those skilled in the art should easily realize that, in combination with the units and algorithm steps of each example described in the embodiments disclosed herein, the present invention can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed in the form of hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described function for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0074] The embodiments of the present invention can perform functional module division according to the above method examples. For example, each functional module can be divided corresponding to each function, or two or more functions can be integrated into one processing module. The above integrated module can be implemented in the form of hardware or in the form of a software functional module. It should be noted that the division of modules in the embodiments of the present invention is illustrative, only a logical functional division, and there may be other division methods in actual implementation.

[0075] The processor in this specification can also have the function of a memory. The memory is used to store the computer execution instructions for executing the solution of the present invention and is controlled by the processor to execute. The processor is used to execute the computer execution instructions stored in the memory, thereby implementing the method provided by the embodiments of the present invention.

[0076] The memory can be a read-only memory (ROM) or other types of static storage devices that can store static information and instructions, a random access memory (RAM) or other types of dynamic storage devices that can store information and instructions, or an electrically erasable programmable read-only memory (EEPROM), a compact disc read-only memory (CD-ROM) or other optical disc storage, optical disc storage (including compressed optical discs, laser discs, optical discs, digital versatile discs, Blu-ray discs, etc.), magnetic disk storage media or other magnetic storage devices, or any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer, but is not limited thereto. The memory can exist independently and be connected to the processor through a communication line. The memory can also be integrated with the processor.

[0077] Optionally, the computer-executable instructions in the embodiments of the present invention may also be referred to as application program codes, and the embodiments of the present invention do not make specific limitations thereto.

[0078] The methods disclosed in the embodiments of the present invention above can be applied to a processor or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the integrated logic circuit in the hardware of the processor or the instructions in the form of software. The above-mentioned processor may be a general-purpose processor, a digital signal processor (DSP), an ASIC, a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present invention can be directly embodied as being executed and completed by the hardware decoding processor, or executed and completed by the combination of the hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory, and the processor reads the information in the memory and combines its hardware to complete the steps of the above method.

[0079] Although the present invention has been described in conjunction with various embodiments herein, however, in the process of implementing the claimed invention, those skilled in the art can understand and achieve other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "one" does not exclude a plurality. A single processor or other unit may implement several functions recited in the claims. Certain measures are recited in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0080] Although the present invention has been described in connection with specific features and their embodiments, it will be apparent that various modifications and combinations can be made without departing from the spirit and scope of the invention. Accordingly, the present specification and drawings are merely exemplary illustrations of the invention defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of the invention. Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these changes and modifications.

Claims

1. A typhoon center positioning method based on SAR satellites, characterized in that, The method includes: Obtaining the basic data of the SAR satellite according to the typhoon path information; the basic data includes at least SAR satellite data and auxiliary data; The auxiliary data includes at least wind field auxiliary data and sea ice edge line auxiliary data; Performing sea surface wind speed and direction inversion based on the basic data to obtain inversion data; According to the inversion data, using the gradient wind equation, wind profile equation and maximum wind speed to determine the high wind speed area of the typhoon; According to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, horizontal divergence field and composite field of the high wind speed area, determining the position range of the typhoon center point; Locating the typhoon center that meets the preset accuracy according to the position range of the typhoon center point.

2. The typhoon center positioning method based on SAR satellites according to claim 1, characterized in that Performing sea surface wind speed and direction inversion based on the basic data to obtain inversion data, including: Performing image preprocessing on the SAR satellite data, calculating and dividing the wind field units according to the requirements of wind field unit division of sea surface wind field products with different resolutions; Using the sea ice edge line auxiliary data to perform sea ice identification on the divided wind units; Using the geophysical model function to perform co-polarization wind speed inversion and cross-polarization wind speed inversion on the sea surface wind speed and direction; Then, according to the reference wind direction of the wind field unit obtained from the numerical model wind field data, eliminating the wind direction ambiguity of the SAR sea surface wind field inversion result to obtain the inversion data that meets the requirements.

3. The typhoon center positioning method based on SAR satellite according to claim 2, characterized in that, Using the geophysical model function to perform co-polarization wind speed inversion and cross-polarization wind speed inversion on the sea surface wind speed and direction, including: When the wind speed is less than the preset threshold, using the sea surface wind direction and observation geometry data, and selecting the CMOD model of the GMF geophysical model function to perform sea surface wind speed inversion, the CMOD model is a function model of sea surface wind speed, sea surface wind direction and radar incident angle, and the CMOD model is expressed as: ； Among them, is the backscattering coefficient, represents the relative wind direction, represents the empirical parameter. B0, B1, and B2 are functions of the sea surface wind speed and the incident angle, and are all constants; When the wind speed is greater than or equal to the preset threshold, using the formula: ； Using the linear relationship model between the cross-polarization backscattering coefficient and the sea surface wind speed to perform sea surface wind speed inversion, where U is the sea surface wind speed, and a and b are both fitting coefficients of the linear relationship.

4. The typhoon center positioning method based on SAR satellite according to claim 1, characterized in that According to the inversion data, using the gradient wind equation, wind profile equation and maximum wind speed to determine the high wind speed area of the typhoon, including: According to the inversion data, using the gradient wind equation: ； Determine the radial range of the high wind speed region; wherein, is the radial wind, w is the vertical velocity, r is the radial coordinate, z is the vertical coordinate, and v is the horizontal velocity component, the meridional velocity component of the gradient wind, and f is the Coriolis parameter, represents the shear stress between the z direction and the r direction, is the fluid density, the remaining external forces in the horizontal direction; Using the wind profile equation: ； Determine the distribution range of the high wind speed area in the vertical direction; among them, represents the characteristic wind speed, represents the maximum wind speed, is the air density, is the base of the natural logarithm function, r is the distance from the observation point to the cyclone center, RMW is the radius of the maximum wind speed, B is the proportionality coefficient, and P is the pressure; Determining the position of the maximum wind speed, taking the maximum wind speed position as the center, estimating the horizontal range of the high wind speed area according to the size characteristics and wind field structure characteristics of the typhoon, and combining the actual wind speed observation data to adjust the horizontal range of the high wind speed area to obtain the typhoon high wind speed area that meets the conditions.

5. The typhoon center positioning method based on SAR satellite according to claim 1, characterized in that, According to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, horizontal divergence field and composite field of the high wind speed area, determining the position range of the typhoon center point, including: Using the formula: ； Calculate the absolute vorticity of the vorticity field, where, is the absolute vorticity, is the relative vorticity, is the planetary vorticity; Using the formula: ； Calculate the relative vorticity of the vorticity field, where, is the three-dimensional wind vector, and we get: ； The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as: ； The difference form expression of the vertical component of the relative vorticity of the vorticity field is: ； The differential expression of the horizontal divergence of the divergence field is: ； The difference form expression of the horizontal divergence of the divergence field is: ； Determine the product of the vorticity field and the divergence field as the composite field; Based on the vorticity field, the divergence field, and the composite field, determine the longitude and latitude and wind speed corresponding to the positive maximum value of the vorticity field in the high wind speed area, the longitude and latitude and wind speed corresponding to the negative minimum value of the divergence field, and the longitude and latitude and wind speed corresponding to the negative minimum value of the composite field, to obtain the longitude and latitude and wind speed of the wind direction rotation center point, the wind direction convergence center point, and the wind direction composite field center point; Determine the center point position with the minimum wind speed among the three center points as the potential center point, and determine the longitude and latitude range of ±0.5° near the potential center point as the typhoon center point position range.

6. The typhoon center positioning method based on SAR satellite according to claim 5, characterized in that, Locate the typhoon center that meets the preset accuracy according to the typhoon center point position range, including: Search for the point with the minimum wind speed within the typhoon center point position range; Select different search sizes according to the different sizes of the wind field resolution. For a low-resolution wind field, sort the wind speeds of each wind vector unit in the area near the typhoon center from small to large with the first search size, and record the longitude and latitude positions corresponding to the wind speeds at the same time. Select the point with the minimum wind speed as the typhoon center; For a high-resolution wind field, slide and calculate the average wind speed within each search size in the area near the typhoon center with the second search size: ； Among them, the second search size is greater than the first search size, k is the window size, x and y are the indexes of matrix A near the typhoon center, i and j are the indexes of the output matrix B. By recording the longitude and latitude of the starting grid point, sort the values in the average wind speed matrix B in the area, determine the grid point with the minimum average wind speed and the corresponding longitude and latitude, and determine the grid point with the minimum average wind speed as the typhoon center point.

7. The typhoon center positioning method based on SAR satellites according to claim 6, wherein The method further includes: Calculate the wind circle radius; The calculation of the wind circle radius includes: Based on the distribution characteristics of the wind speed with the radius, combine the wind speed thresholds in different regions of the typhoon to divide the wind circle range; According to the longitude and latitude, the maximum wind speed, and the radius of the maximum wind speed of the typhoon center point, calculate the parameter B of the Holland model: ； The wind speed profile model is expressed as: ； Among them, the longitude and latitude are (lat0, lon0), vamx represents the maximum wind speed, RMW represents the radius of the maximum wind speed, the radius of the maximum wind speed is the distance between the maximum wind speed wind unit and the typhoon center, vmax is the maximum wind speed, and the maximum wind speed is the maximum wind speed with the typhoon center as the origin and within the preset radius; With the typhoon center point as the origin, divide the wind speed into four quadrants, calculate the wind speeds of the observation points within different radii from the typhoon center point respectively, form the typhoon radial wind speed profile, and obtain the size of the wind circle radius of each quadrant.

8. A typhoon center positioning device based on a SAR satellite, characterized in that, The device includes: The basic data determination module is used to obtain the basic data of the SAR satellite according to the typhoon path information; the basic data includes at least SAR satellite data and auxiliary data; the auxiliary data includes at least wind field auxiliary data and sea ice edge line auxiliary data; The sea surface wind speed and direction inversion module is used to perform sea surface wind speed and direction inversion based on the basic data to obtain inversion data; The typhoon high wind speed area determination module is used to determine the high wind speed area of the typhoon according to the inversion data by using the gradient wind equation, the wind profile equation, and the maximum wind speed; The typhoon center point position range determination module is used to determine the typhoon center point position range according to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field, horizontal divergence field and composite field of the high wind speed area of the typhoon; The typhoon center determination module is used to locate the typhoon center that meets the preset accuracy according to the typhoon center point position range.

9. A typhoon center positioning device based on an SAR satellite, characterized in that the device Including: A memory, a processor, and a communication interface coupled to the processor; A computer program that can be run by the processor is stored on the memory; When the processor runs the computer program, it executes the method for positioning the typhoon center based on SAR satellites according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that, Instructions are stored in the computer storage medium, and when the instructions are run by the processor, the method for positioning the typhoon center based on SAR satellites according to any one of claims 1 to 7 is realized.

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