A typhoon center positioning method, device and equipment based on SAR satellite

Abstract

The present invention discloses a typhoon center positioning method, device, and equipment based on SAR satellites, relating to the field of marine microwave remote sensing technology, and is used to solve the problem that typhoon positioning methods in the prior art cannot accurately extract the typhoon center position and have low positioning accuracy of the typhoon center. The method comprises: obtaining basic data from SAR satellites based on typhoon path information; performing sea surface wind speed and direction inversion based on the basic data to obtain inversion data; determining the typhoon's high wind speed area based on the inversion data using the gradient wind equation, the wind profile equation, and the maximum wind speed; determining the typhoon's center point position range based on the cyclonic vortex structure of the typhoon and the vertical vorticity field, the horizontal divergence field, and the composite field of the high wind speed area; and locating the typhoon center to a predetermined accuracy based on the typhoon center point position range. The technical solution provided by the present invention can improve the positioning accuracy of the typhoon center.

Description

Technical Field

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

[0002] Typhoons are a special type of tropical cyclone. Their arrival is often accompanied by rainfall, contributing to significant rainfall in my country's coastal areas. They also bring inevitable natural disasters. Typhoon identification and the location of typhoon centers are crucial for both typhoon forecasting and weather research, but methods for detecting typhoons are limited.

[0003] Traditional typhoon positioning methods include visual estimation, cloud image center positioning, physical model method and image processing method. Visual estimation method: In the early days, typhoon center positioning was mainly done by forecasters through visual estimation based on satellite cloud images and other data. There are problems such as long positioning time, lack of stability and consistency, and it is difficult to accurately determine the position of the typhoon center due to factors such as the fluctuation of cloud tops, solar altitude angle, and asymmetry of cloud systems. Cloud image center positioning method: Using geostationary or polar-orbiting satellite detection data from meteorological satellites, the brightness temperature and other characteristics are analyzed to find the typhoon center. However, when the typhoon position changes or the cloud system characteristics are atypical, the brightness temperature characteristics may not be obvious, affecting the positioning accuracy. Physical model method: Based on physical models such as typhoon flow fields, the least squares method and other methods 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 large deviations in the positioning results. Image processing method: Processing satellite cloud images and other images, such as using cloud edge detection and fitting to determine the typhoon center; however, this method is computationally intensive, has high requirements on image quality, and is difficult to process dynamically changing typhoon cloud images in real time.

[0004] Typhoons are sudden, unleashing strong winds, heavy rains, storm surges, and other disasters that pose a serious threat to industrial and agricultural production, transportation, and the safety of people's lives and property. Accurately and promptly locating a typhoon's center is crucial for accurate typhoon forecasting and disaster prevention and mitigation decisions. Furthermore, cloud structures are complex and dynamic, varying significantly between typhoons of varying intensities and stages of development. For example, some typhoons have a clear eye, while others do not. Furthermore, cloud systems are constantly changing, making the use of cloud characteristics for positioning difficult. Remote sensing satellites have become the primary method for in-situ observation of offshore typhoons. SAR satellites, with their high spatial and temporal resolution, are a crucial tool for typhoon detection.

[0005] The existing typhoon positioning methods 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 solution based on SAR satellites. Summary of the Invention

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

[0008] In a first aspect, the present invention provides a typhoon center positioning method based on SAR satellites, the method comprising:

[0009] Acquire basic data of SAR satellites 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 auxiliary data;

[0010] Performing sea surface wind speed and direction inversion based on the basic data to obtain inversion data;

[0011] Determining the high wind speed area of ​​the typhoon using the gradient wind equation, the wind profile equation, and the maximum wind speed based on the inversion data;

[0012] Determine the location range of the typhoon center point based on the cyclonic vortex structure of the typhoon, the vertical vorticity 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;

[0013] The typhoon center is located with a preset accuracy according to the typhoon center point position range.

[0014] Optionally, performing sea surface wind speed and direction inversion based on the basic data to obtain inversion data includes:

[0015] Performing image preprocessing on the SAR satellite data, calculating the wind field units according to the requirements of wind field unit division of sea surface wind field products with different resolutions, and dividing them;

[0016] Using the sea ice edge line auxiliary data, the divided wind units are marked with sea ice;

[0017] Using geophysical model functions, the wind speed and direction of the sea surface wind field are inverted for both co-polarization wind speed and cross-polarization wind speed.

[0018] Then, according to the wind unit reference wind direction obtained from the numerical model wind field data, the SAR sea surface wind field inversion results are fuzzy-free to obtain inversion data that meets the requirements.

[0019] Optionally, geophysical model functions are used to perform co-polarization wind speed inversion and cross-polarization wind speed inversion on the sea surface wind speed and direction, including:

[0020] When the wind speed is less than the preset threshold, the sea surface wind direction and observation geometry data are used to invert the sea surface wind speed using the CMOD model of the GMF geophysical model function. The CMOD model is a function model of the sea surface wind speed, sea surface wind direction and radar incident angle. The CMOD model is expressed as:

[0021] ;

[0022] in, is the backscattering coefficient, Indicates the relative wind direction, represents empirical parameters, B0, B1 and B2 are functions of sea surface wind speed and incident angle, and are all constants;

[0023] When the wind speed is greater than or equal to the preset threshold, the formula is used:

[0024] ;

[0025] The sea surface wind speed is inverted using the linear relationship model between the cross-polarization backscatter 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.

[0026] Optionally, determining the high wind speed area of ​​the typhoon using the gradient wind equation, the wind profile equation, and the maximum wind speed based on the inversion data includes:

[0027] According to the inversion data, the gradient wind equation is used:

[0028] ;

[0029] Determine the radial extent of the high wind speed area; 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, Other external forces in the horizontal direction;

[0030] Using the wind profile equation:

[0031] ;

[0032] Determine the vertical distribution range of high wind speed areas; represents the characteristic wind speed, Indicates 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 maximum wind speed radius, B is the proportional coefficient, and P is the pressure;

[0033] Determine the maximum wind speed position, take the maximum wind speed position 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 adjust the horizontal range of the high wind speed area in combination with actual wind speed observation data to obtain a typhoon high wind speed area that meets the conditions.

[0034] Optionally, the typhoon center position range is determined based on the cyclonic vortex structure of the typhoon, the vertical vorticity 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, including:

[0035] Using the formula:

[0036] ;

[0037] Calculate the absolute vorticity of the vorticity field, where is the absolute vorticity, is the relative vorticity, is the planetary vorticity;

[0038] Using the formula:

[0039] ;

[0040] Calculate the relative vorticity of the vorticity field, where is the three-dimensional wind vector, we get:

[0041] ;

[0042] The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as:

[0043] ;

[0044] The differential expression of the vertical component of the relative vorticity of the vorticity field is:

[0045] ;

[0046] The differential expression of the horizontal divergence of the divergence field is:

[0047] ;

[0048] The differential expression of the horizontal divergence of the divergence field is:

[0049] ;

[0050] determining the product of the vorticity field and the divergence field as a composite field;

[0051] According to the vorticity field, the divergence field and the composite field, determining 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 obtaining 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;

[0052] The center point with the smallest wind speed among the three center points is determined as the potential center point, and the longitude and latitude range of ±0.5° near the potential center point is determined as the typhoon center point position range.

[0053] Optionally, locating the typhoon center with a preset accuracy according to the typhoon center position range includes:

[0054] Find the point with the minimum wind speed within the range of the typhoon center point;

[0055] Different search sizes are selected according to the wind field resolution. For low-resolution wind fields, the wind speed of each wind vector unit in the area near the typhoon center is sorted from small to large using the first search size. The longitude and latitude corresponding to the wind speed are recorded at the same time, and the point with the minimum wind speed is selected as the typhoon center.

[0056] For high-resolution wind fields, the average wind speed within each search size in the area near the typhoon center is calculated by sliding the second search size:

[0057] ;

[0058] Among them, the second search size is larger than the first search size, k is the window size, x, y are the indexes of the matrix A near the typhoon center, i, j are the indexes of the output matrix B, and by recording the longitude and latitude of the starting grid point, the values ​​in the average wind speed matrix B in the area are sorted to determine the grid point with the smallest average wind speed and the corresponding longitude and latitude, and the grid point with the smallest average wind speed is determined as the typhoon center.

[0059] Optionally, the method further includes:

[0060] Calculate the radius of the wind circle;

[0061] The calculation of the wind circle radius includes:

[0062] Based on the distribution characteristics of wind speed with radius, the wind circle range is divided into two parts according to the wind speed thresholds in different typhoon areas.

[0063] Calculate the parameter B of the Holland model based on the latitude and longitude of the typhoon center, the maximum wind speed, and the maximum wind speed radius:

[0064] ;

[0065] The wind speed profile model is expressed as:

[0066] ;

[0067] Among them, the longitude and latitude are (lat0, lon0), vamx represents the maximum wind speed, RMW represents the maximum wind speed radius, the maximum wind speed radius 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 within the preset radius with the typhoon center as the origin;

[0068] Taking the typhoon center as the origin, the wind speed is divided into four quadrants. The wind speeds of observation points within different radii from the typhoon center are calculated to form the typhoon radial wind speed profile and obtain the radius of the wind circle in each quadrant.

[0069] Compared with the prior art, the present invention provides a typhoon center positioning method based on SAR satellites. The method obtains basic SAR satellite data based on typhoon path information; performs sea surface wind speed and direction inversion based on the basic data to obtain inversion data; determines the typhoon's high wind speed area using the gradient wind equation, wind profile equation, and maximum wind speed based on the inversion data; determines the typhoon's center position range based on the typhoon's cyclonic vortex structure, the vertical vorticity field in the high wind speed area, the horizontal divergence field in the high wind speed area, and the composite field in the high wind speed area; and locates the typhoon center to a predetermined accuracy based on the typhoon center position range. Using high-resolution SAR satellite data to locate the typhoon center, the typhoon structure is clearer and the center positioning accuracy is higher. The wind field inverted from the SAR data comprehensively considers multiple typhoon characteristics to accurately extract the typhoon center position, thereby improving the typhoon center positioning accuracy, achieving accurate typhoon center positioning and calculating complete elements such as the maximum average wind speed and wind circle radius, improving typhoon forecasting and real-time monitoring capabilities, and reducing typhoon losses to a certain extent.

[0070] In a second aspect, the present invention provides a typhoon center positioning device based on a SAR satellite, the device comprising:

[0071] A basic data determination module is used to obtain basic data of SAR satellites based on 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 auxiliary data;

[0072] A sea surface wind speed and direction inversion module is used to invert the sea surface wind speed and direction based on the basic data to obtain inversion data;

[0073] A typhoon high wind speed area determination module is used to determine the typhoon high wind speed area based on the inversion data using the gradient wind equation, the wind profile equation and the maximum wind speed;

[0074] A typhoon center position range determination module is used to determine the typhoon center position range based on the cyclonic vortex structure of the typhoon, the vertical vorticity 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;

[0075] The typhoon center determination module is used to locate the typhoon center with a preset accuracy according to the typhoon center point position range.

[0076] In a third aspect, the present invention provides a typhoon center positioning device based on a SAR satellite, the device comprising:

[0077] A memory, a processor, and a communication interface coupled to the processor; the memory stores a computer program that can be run by the processor; when the processor runs the computer program, it executes the above-mentioned typhoon center positioning method.

[0078] In a fourth aspect, the present invention provides a computer storage medium having instructions stored therein, which, when executed, implement the above-mentioned typhoon center positioning method.

[0079] The technical effects achieved by the device-type solution provided in the second aspect, the equipment-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 repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0081] Figure 1 This is a flowchart of a typhoon center positioning method based on SAR satellites;

[0082] Figure 2 This is an overall flow chart of a typhoon center positioning method based on SAR satellites;

[0083] Figure 3 This is a structural diagram of a typhoon center positioning device based on SAR satellite;

[0084] Figure 4 This is a structural diagram of a typhoon center positioning device based on SAR satellites. DETAILED DESCRIPTION

[0085] To facilitate a clear description of the technical solutions of the embodiments of the present invention, the words "first" and "second" are used in the embodiments of the present invention to distinguish between identical or similar items with substantially the same functions and effects. For example, the first threshold and the second threshold are merely used to distinguish between different thresholds and do not limit their order. Those skilled in the art will understand that the words "first" and "second" do not limit the quantity or execution order, and the words "first" and "second" do not necessarily mean different.

[0086] It should be noted that, in the present invention, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the present invention should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0087] In the present invention, "at least one" means one or more, and "more" means two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. The character " / " generally indicates that the previous and next associated objects are in an "or" relationship. "At least one of the following items" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, at least one of a, b or c can mean: 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, c can be single or plural.

[0088] In the existing technology, the means of locating the typhoon center are all based on the inversion of the wind field by the scatterometer, and the process is to first determine the maximum wind speed area, and then determine the wind direction vorticity and divergence, with poor accuracy. Typhoons are one of the serious natural disasters. Accurately locating the typhoon center is of great reference and application value for typhoon forecasting and monitoring, and has certain guiding significance for regional and even global weather and climate research. However, conventional statistical data and observation data are difficult to accurately and completely calculate factors such as the typhoon center position. Based on the existing technology, this solution further optimizes the specific algorithm for wind speed screening, the calculation method of vorticity and divergence, the method for determining the typhoon center position range, the typhoon center calculation method and other details, so that it has a significant improvement in positioning accuracy and efficiency.

[0089] The present invention uses high-resolution SAR satellite data to locate the center of a typhoon, making the typhoon structure clearer and the center positioning accuracy higher. The typhoon center is roughly extracted based on the wind field inverted from the SAR data, taking into account the high wind speed characteristics, vortex rotation characteristics, and composite field characteristics of the typhoon. The average wind speed is calculated by searching the results of the rough extraction, and an improved scheme is used to determine the position range of the typhoon center point and the calculation of the typhoon center. Specifically, based on the inversion data, the gradient wind equation, the wind profile equation, and the maximum wind speed are used to determine the high wind speed area of ​​the typhoon; based on the cyclonic vortex structure of the typhoon, the position range of the typhoon center point is determined based on the vertical vorticity 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, the typhoon center point position range is determined, and the typhoon center is further calculated. The typhoon center position can be accurately extracted, thereby improving the positioning accuracy of the typhoon center. Next, the scheme provided in the embodiment of this specification is described in conjunction with the accompanying drawings:

[0090] like Figure 1 As shown, the process may include the following steps:

[0091] Step 110: Obtain basic data of the SAR satellite according to the typhoon path information.

[0092] 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 auxiliary data.

[0093] Obtain typhoon path information, SAR observation data, ERA5 wind field auxiliary data, and sea ice edge auxiliary data released by credible institutions. Specifically, combine the typhoon path information to determine the time period and spatial range of the typhoon's impact, and then filter out the SAR satellite data acquired within this time period and area from the data source. For example, if a typhoon passes through a certain sea area on a certain day, select the satellite observation data of the sea area for a period of time before and after the typhoon passes. The acquired raw SAR satellite data can be pre-processed by operations such as radiometric calibration, geometric correction, and denoising to improve data quality and usability. Radiometric calibration can convert digital signals into physical quantities, geometric correction can correct the geometric deformation of the image, and denoising can remove interference signals in the image.

[0094] Ancillary wind data can include reanalysis data, which integrates multiple observational data and numerical models, offering high temporal and spatial resolution and good data quality. For example, ERA5 reanalysis data provides global atmospheric parameters, including wind data. Wind data corresponding to the time and space of typhoon paths can be selected as auxiliary data.

[0095] Auxiliary data for determining the sea ice edge generally uses the contour line where the sea ice concentration reaches a certain threshold (e.g., 15%) as the sea ice edge. In conditions where the sea ice edge is relatively clear and cloud cover is minimal, optical satellite remote sensing data can be used to extract the sea ice edge. For example, MODIS satellite data processes and analyzes visible and infrared imagery to identify the boundary between sea ice and open water, thereby obtaining information on the sea ice edge. These in-situ observations can be used to verify and calibrate the sea ice edge derived from satellite remote sensing, and are particularly important for determining complex sea ice morphologies and edge regions.

[0096] Step 120: Perform sea surface wind speed and direction inversion based on the basic data to obtain inversion data.

[0097] Sea surface wind speed and direction inversion includes co-polarization wind speed inversion and cross-polarization wind speed inversion.

[0098] Step 130: Based on the inversion data, the gradient wind equation, the wind profile equation and the maximum wind speed are used to determine the high wind speed area of ​​the typhoon.

[0099] Gradient wind is the actual wind that exists on the ground or at sea. It is balanced by the horizontal pressure gradient force, the Coriolis force, and the inertial centrifugal force. In low-pressure systems such as typhoons, the gradient wind equation can better describe the relationship between wind speed and pressure field. Using the pressure field data in the typhoon area obtained by SAR satellite inversion, the pressure gradient can be calculated. Combined with the known Coriolis parameters (determined by the latitude) and parameters such as air density, they are substituted into the gradient wind equation to solve the wind speed at different locations.

[0100] The wind profile equation describes how wind speed varies with altitude. The form of the wind profile equation varies under different atmospheric stability conditions. Common examples include the logarithmic wind profile equation. Using wind speed data near the sea surface acquired by SAR satellites, combined with local atmospheric stability conditions and parameters such as surface roughness length, the wind profile equation is used to extrapolate wind speeds at different altitudes.

[0101] In this scheme, the gradient wind equation is used to determine the radial range of the high wind speed area, and the wind profile equation is used to determine the distribution range of the high wind speed area in the vertical direction.

[0102] Step 140: Determine the position range of the typhoon center point based on the cyclonic vortex structure of the typhoon, the vertical vorticity 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.

[0103] According to the cyclonic vortex structure of the typhoon, based on the vertical vorticity field in the high wind speed area, the horizontal divergence field in the high wind speed area, and the composite field in the high wind speed area, the location range of the typhoon center is determined, and the typhoon center is further calculated.

[0104] Step 150: Locate the typhoon center with a preset accuracy according to the typhoon center position range.

[0105] Step 140 can only determine the range of the typhoon center position. If you want to locate the precise typhoon center, you need to further adopt the improved solution of the present invention to determine the grid point with the smallest average wind speed and the corresponding longitude and latitude, and use this point as the wind speed center, that is, the final typhoon center.

[0106] Figure 1 The proposed method obtains basic SAR satellite data based on typhoon path information; inverts sea surface wind speed and direction based on this basic data to obtain inversion data; uses the inversion data to determine the typhoon's high wind speed region using the gradient wind equation, wind profile equation, and maximum wind speed; determines the typhoon's center location range based on the typhoon's cyclonic vortex structure, the vertical vorticity field, the horizontal divergence field, and the composite field in the high wind speed region; and locates the typhoon center within the typhoon center location range to a predetermined accuracy. Using high-resolution SAR satellite data to locate the typhoon center provides a clearer typhoon structure and higher center positioning accuracy. The wind field inverted from the SAR data comprehensively considers multiple typhoon characteristics to accurately extract the typhoon center, improving its positioning accuracy. Accurately locate the typhoon center and calculate complete elements such as the maximum average wind speed and wind circle radius are achieved, improving typhoon forecasting and real-time monitoring capabilities, and to a certain extent, reducing typhoon-related losses.

[0107] based on Figure 1 The present specification also provides some specific implementation methods of the method, which are described below.

[0108] Specifically, if Figure 2 As shown, the present invention obtains corresponding SAR satellite data through typhoon path information released by a trusted organization, and performs sea surface wind speed and direction inversion based on SAR satellite data and other auxiliary data; screens the location of the typhoon's strong wind area according to the sea surface wind speed; calculates and establishes 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 according to the cyclonic vortex structure of the typhoon, and performs center position calculation and minimum wind speed calculation respectively to determine the potential typhoon center point location; searches and calculates the average wind speed based on the range near the potential typhoon center point, selects the minimum wind speed point as the typhoon center, and calculates the typhoon wind circle radius based on the typhoon center position; and evaluates the positioning accuracy of the typhoon center position. The typhoon center position can be accurately extracted, which improves the positioning accuracy of the typhoon center. Next, the specific implementation means of the process steps provided by the present invention are further explained:

[0109] Step 120, when implemented, may include:

[0110] Performing image preprocessing on the SAR satellite data, calculating the wind field units according to the requirements of wind field unit division of sea surface wind field products with different resolutions, and dividing them;

[0111] Using the sea ice edge line auxiliary data, the divided wind units are marked with sea ice;

[0112] Using geophysical model functions, the wind speed and direction of the sea surface wind field are inverted for both co-polarization wind speed and cross-polarization wind speed.

[0113] Then, according to the wind unit reference wind direction obtained from the numerical model wind field data, the SAR sea surface wind field inversion results are fuzzy-free to obtain inversion data that meets the requirements.

[0114] Furthermore, the SAR observation images of the sea surface wind field inversion undergo image preprocessing. Wind field units are then calculated and divided according to the requirements for wind field unit division for sea surface wind field products of different resolutions. Sea ice marking is performed on these wind units using auxiliary data from the sea ice edge. Geophysical model functions are used to invert parameters such as wind speed and direction. The SAR sea surface wind field inversion results are then deblurred using wind unit reference wind directions derived from numerical model wind field data.

[0115] When the wind speed is less than a preset threshold, the sea surface wind direction and observation geometry data are used to invert the sea surface wind speed using the CMOD model of the GMF geophysical model function. The CMOD model is a function model of the sea surface wind speed, sea surface wind direction and radar incident angle.

[0116] Because co-polarization saturates at higher wind speeds (approximately 25 m / s), limiting its applicability in extremely high wind speeds, sea surface wind speed inversion is performed using a linear relationship model between the cross-polarization backscatter coefficient and sea surface wind speed during hurricane or typhoon conditions. Therefore, when the wind speed is greater than or equal to a preset threshold, sea surface wind speed inversion is performed using this linear relationship model.

[0117] Specifically, 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 formula (1):

[0118] (1)

[0119] in, is the backscattering coefficient, Indicates the relative wind direction, that is, the angle between the sea surface wind direction and the radar beam azimuth (0°~360°). represents empirical parameters, B0, B1 and B2 are functions of sea surface wind speed and incident angle, and are all constants;

[0120] When the wind speed is greater than or equal to the preset threshold, formula (2) is used:

[0121] (2)

[0122] The sea surface wind speed is inverted using the linear relationship model between the cross-polarization backscatter 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.

[0123] Step 130, when implemented, may include:

[0124] Under normal circumstances, the typhoon structure can be divided into the typhoon eye area in the horizontal direction. The wind speed in the eye area decreases rapidly or becomes calm, with an average diameter of about 45km; the strong wind area, also known as the typhoon outer ring, with a diameter generally reaching 400-600km, and the outer wind speed can reach 15m / s. The wind speed increases rapidly inward; the typhoon vortex area, also known as the eyewall, is the typhoon middle ring, and is also a maximum wind speed belt distributed around the typhoon, with an average width of 10-20km. It is the area where the typhoon's destructive power is the most violent and concentrated.

[0125] The typhoon center is located in the typhoon eye area. In a fully developed strong cyclone, the wind force near the center is the strongest and the air pressure is the lowest. In a stable axisymmetric mode, the radial wind equation can be expressed as the gradient tangential wind as formula (3):

[0126] (3)

[0127] Determine the radial extent of the high wind speed area; 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, Other external forces in the horizontal direction;

[0128] The wind profile equation is used, such as formula (4):

[0129] (4)

[0130] Determine the vertical distribution range of high wind speed areas; represents the characteristic wind speed, Indicates 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 maximum wind speed radius, B is the proportional coefficient, and P is the pressure;

[0131] The maximum wind speed location is determined. With the maximum wind speed location as the center, the horizontal range of the high wind speed area is estimated according to the size characteristics and wind field structure characteristics of the typhoon. Combined with the actual wind speed observation data, the horizontal range of the high wind speed area is adjusted to obtain the 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 winds, destructive winds and hurricanes. Generally, 17 m / s is set as the high wind speed search threshold, and the observation area with wind speeds greater than 17 m / s is searched as the high wind speed area.

[0132] Since extreme points of composite field values ​​may also appear in non-typhoon structure areas, this is related to the typhoon development stage and intensity. During the formation and development period of a typhoon, the typhoon structure is not complete, and a clear eye profile and a solid cloud wall have not yet formed. 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.

[0133] Step 140, when implemented, may include:

[0134] Using formula (5):

[0135] (5)

[0136] Calculate the absolute vorticity of the vorticity field, where is the absolute vorticity, is the relative vorticity, is the planetary vorticity;

[0137] Using formula (6):

[0138] (6)

[0139] Calculate the relative vorticity of the vorticity field, where is the three-dimensional wind vector, and formula (7) is obtained:

[0140] (7)

[0141] The wind field on the sea surface where a typhoon passes has a distinct cyclonic vortex structure, often accompanied by strong winds, rainstorms and severe weather. Vorticity represents the rotational characteristics of atmospheric motion. Due to the nearly horizontal motion of the atmosphere, only the vertical component of the relative vorticity is generally considered. Due to the Coriolis force, in the northern hemisphere, the wind field converges counterclockwise toward the center of the typhoon, and in the southern hemisphere, it rotates counterclockwise. There should be a local maximum point at the center of the typhoon. The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as formula (8):

[0142] (8)

[0143] The differential expression of the vertical component of the relative vorticity of the vorticity field is formula (9):

[0144] (9)

[0145] Due to the nearly horizontal motion of the atmosphere, only the horizontal divergence of the atmospheric motion is considered. According to the structural characteristics of the typhoon, the divergence field at the typhoon center should be negative and the center can be at the local minimum point. The differential expression of the horizontal divergence of the divergence field is formula (10):

[0146] (10)

[0147] The differential expression of the horizontal divergence of the divergence field is formula (11):

[0148] (11)

[0149] The product of the vorticity field and the divergence field is determined as a composite field; the composite field not only takes into account 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 center of the typhoon. The size of the composite field can be determined by Perform calculations.

[0150] According to the vorticity field, the divergence field and the composite field, determining 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 obtaining 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;

[0151] The center point with the smallest wind speed among the three center points is determined as the potential center point, and the longitude and latitude range of ±0.5° near the potential center point is determined as the typhoon center point position range.

[0152] According to the vorticity field, divergence field and composite field calculated above, 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 are found to obtain the longitude and latitude and wind speed of the three center points. The three center points represent the wind direction rotation center point, the wind direction convergence center point and the wind direction composite field center point respectively. The wind speed at the typhoon center point should be the smallest, so the center point with the smallest wind speed among the three center points is selected 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 also be the point with the minimum wind speed in the area near the typhoon. Therefore, with the wind direction center point as the center, the point with the minimum wind speed is searched in the nearby area. Here, the longitude and latitude range of ±0.5° near the potential center point is selected as the area near the typhoon center point.

[0153] Step 150, the specific implementation process may include:

[0154] Find the point with the minimum wind speed within the range of the typhoon center point;

[0155] Different search sizes are selected according to the wind field resolution. For low-resolution wind fields, the wind speed of each wind vector unit in the area near the typhoon center is sorted from small to large using the first search size. The longitude and latitude corresponding to the wind speed are recorded at the same time, and the point with the minimum wind speed is selected as the typhoon center.

[0156] For high-resolution wind fields, the average wind speed within each search size in the area near the typhoon center is calculated by sliding the second search size, as shown in formula (12):

[0157] (12)

[0158] Among them, the second search size is larger than the first search size, k is the window size, x, y are the indexes of the matrix A near the typhoon center, i, j are the indexes of the output matrix B, and by recording the longitude and latitude of the starting grid point, the values ​​in the average wind speed matrix B in the area are sorted to determine the grid point with the smallest average wind speed and the corresponding longitude and latitude, and the grid point with the smallest average wind speed is determined as the typhoon center.

[0159] More specifically, because typhoon wind direction often comes from numerical model information, the typhoon center location determined by these models often has large deviations. Therefore, the search for the point with the minimum wind speed in the area near the typhoon center (±0.5°) determined above is performed. Different search sizes can be selected depending on the wind field resolution. For low-resolution wind fields, for example, a 1×1 search size can be used. This means that the wind speeds of each wind vector unit in the area near the typhoon center are sorted from small to large, and the corresponding longitude and latitude positions of the wind speeds are recorded. The point with the minimum wind speed is selected as the typhoon center. For high-resolution wind fields, the search size can be increased, for example, using 2×2 or 3×3 search sizes, and slidingly calculating the average wind speed within each search size in the area near the typhoon center.

[0160] In addition, the technical solution provided by the present invention also requires further calculation of the wind circle radius. The wind circle delineation method for the typhoon radial average wind speed profile is generally based on the distribution characteristics of wind speed with radius, combined with the wind speed thresholds of different typhoon regions to divide the wind circle range. Assuming the longitude and latitude of the typhoon center point obtained in (5) is (lat0, lon0), the maximum wind speed is vamx, and the maximum wind speed radius RMW, calculate the parameter B of the Holland model, as shown in formula (13):

[0161] (13)

[0162] The wind speed profile model is expressed as formula (14):

[0163] (14)

[0164] 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.

[0165] According to the model, the wind speed is divided into four quadrants with the typhoon center as the origin. The wind speeds of the observation points within different radii r from the center are calculated to form the typhoon radial wind speed profile. After reaching the maximum wind speed, the r value corresponding to the decay to 17.2m / s is defined as the radius of the level 7 wind circle, and the r value corresponding to the decay to 24.5m / s is defined as the radius of the level 10 wind circle, and the radius of the wind circle in each quadrant is obtained.

[0166] Furthermore, to verify the accuracy of typhoon center positioning, the typhoon center point obtained using the aforementioned method was compared with a trusted CMA best path dataset. This dataset includes typhoon time, typhoon intensity, typhoon center latitude and longitude, typhoon center minimum 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 distance between the located typhoon center position and the CMA center position in the longitudinal, latitudinal, and longitudinal directions were statistically analyzed as typhoon center positioning indicators.

[0167] Based on the same idea, the present invention also provides a typhoon center positioning device based on SAR satellite, such as Figure 3 As shown, the device may include:

[0168] A basic data determination module 310 is configured to obtain basic data of SAR satellites based on 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 auxiliary data;

[0169] A sea surface wind speed and direction inversion module 320 is configured to perform sea surface wind speed and direction inversion based on the basic data to obtain inversion data;

[0170] A typhoon high wind speed area determination module 330 is configured to determine the typhoon high wind speed area based on the inversion data using the gradient wind equation, the wind profile equation, and the maximum wind speed;

[0171] A typhoon center position range determination module 340 is configured to determine the typhoon center position range based on the cyclonic vortex structure of the typhoon, the vertical vorticity 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;

[0172] The typhoon center determination module 350 is configured to locate the typhoon center with a preset accuracy according to the typhoon center point position range.

[0173] based on Figure 3 The device may further include some specific implementation units:

[0174] Optionally, the sea surface wind speed and direction inversion module 320 may include:

[0175] A wind field division unit is used to perform image preprocessing on the SAR satellite data, calculate the wind field units according to the requirements of wind field unit division of sea surface wind field products with different resolutions, and divide them;

[0176] A sea ice identification unit is used to identify sea ice on the divided wind units using the sea ice edge line auxiliary data;

[0177] An inversion unit is used to perform co-polarization wind speed inversion and cross-polarization wind speed inversion on the wind speed and wind direction of the sea surface wind field using a geophysical model function;

[0178] The elimination unit is used to perform wind direction fuzzy elimination on the SAR sea surface wind field inversion result according to the wind unit reference wind direction obtained from the numerical model wind field data, so as to obtain inversion data that meets the requirements.

[0179] Optionally, the inversion unit may include:

[0180] The co-polarization wind speed inversion subunit is used to invert the sea surface wind speed using the sea surface wind direction and observation geometry data when the wind speed is less than a preset threshold. The CMOD model of the GMF geophysical model function is selected 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. The CMOD model is expressed as:

[0181] ;

[0182] in, is the backscattering coefficient, Indicates the relative wind direction, represents empirical parameters, B0, B1 and B2 are functions of sea surface wind speed and incident angle, and are all constants;

[0183] The cross-polarization wind speed inversion subunit is used to use the formula when the wind speed is greater than or equal to the preset threshold:

[0184] ;

[0185] The sea surface wind speed is inverted using the linear relationship model between the cross-polarization backscatter 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.

[0186] Optionally, the typhoon high wind speed area determination module 330 may include:

[0187] The radial range determination unit of the high wind speed area is used to adopt the gradient wind equation according to the inversion data:

[0188] ;

[0189] Determine the radial extent of the high wind speed area; 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, Other external forces in the horizontal direction;

[0190] The high wind speed area is defined in the vertical range of the unit, which is used to adopt the wind profile equation:

[0191] ;

[0192] Determine the vertical distribution range of high wind speed areas; represents the characteristic wind speed, Indicates 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 maximum wind speed radius, B is the proportional coefficient, and P is the pressure;

[0193] The typhoon high wind speed area determination unit is used to determine the maximum wind speed position, take the maximum wind speed position 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 adjust the horizontal range of the high wind speed area in combination with the actual wind speed observation data to obtain a typhoon high wind speed area that meets the conditions.

[0194] Optionally, the typhoon center position range determination module 340 may be used to:

[0195] Using the formula:

[0196] ;

[0197] Calculate the absolute vorticity of the vorticity field, where is the absolute vorticity, is the relative vorticity, is the planetary vorticity;

[0198] Using the formula:

[0199] ;

[0200] Calculate the relative vorticity of the vorticity field, where is the three-dimensional wind vector, we get:

[0201] ;

[0202] The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as:

[0203] ;

[0204] The differential expression of the vertical component of the relative vorticity of the vorticity field is:

[0205] ;

[0206] The differential expression of the horizontal divergence of the divergence field is:

[0207] ;

[0208] The differential expression of the horizontal divergence of the divergence field is:

[0209] ;

[0210] determining the product of the vorticity field and the divergence field as a composite field;

[0211] According to the vorticity field, the divergence field and the composite field, determining 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 obtaining 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;

[0212] The center point with the smallest wind speed among the three center points is determined as the potential center point, and the longitude and latitude range of ±0.5° near the potential center point is determined as the typhoon center point position range.

[0213] Optionally, the typhoon center determination module 350 may be used to:

[0214] Find the point with the minimum wind speed within the range of the typhoon center point;

[0215] Different search sizes are selected according to the wind field resolution. For low-resolution wind fields, the wind speed of each wind vector unit in the area near the typhoon center is sorted from small to large using the first search size. The longitude and latitude corresponding to the wind speed are recorded at the same time, and the point with the minimum wind speed is selected as the typhoon center.

[0216] For high-resolution wind fields, the average wind speed within each search size in the area near the typhoon center is calculated by sliding the second search size:

[0217] ;

[0218] Among them, the second search size is larger than the first search size, k is the window size, x, y are the indexes of the matrix A near the typhoon center, i, j are the indexes of the output matrix B, and by recording the longitude and latitude of the starting grid point, the values ​​in the average wind speed matrix B in the area are sorted to determine the grid point with the smallest average wind speed and the corresponding longitude and latitude, and the grid point with the smallest average wind speed is determined as the typhoon center.

[0219] Optionally, the method further includes:

[0220] Wind circle radius calculation module, used to calculate the wind circle radius;

[0221] The wind circle radius calculation module can be used for:

[0222] Based on the distribution characteristics of wind speed with radius, the wind circle range is divided into two parts according to the wind speed thresholds in different typhoon areas.

[0223] Calculate the parameter B of the Holland model based on the latitude and longitude of the typhoon center, the maximum wind speed, and the maximum wind speed radius:

[0224] ;

[0225] The wind speed profile model is expressed as:

[0226] ;

[0227] Among them, the longitude and latitude are (lat0, lon0), vamx represents the maximum wind speed, RMW represents the maximum wind speed radius, the maximum wind speed radius 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 within the preset radius with the typhoon center as the origin;

[0228] Taking the typhoon center as the origin, the wind speed is divided into four quadrants. The wind speeds of observation points within different radii from the typhoon center are calculated to form the typhoon radial wind speed profile and obtain the radius of the wind circle in each quadrant.

[0229] Based on the same idea, the embodiment of this specification also provides a typhoon center positioning device based on SAR satellite. Figure 4 As shown, the device includes:

[0230] A memory, a processor, and a communication interface coupled to the processor; the memory stores a computer program that can be executed by the processor; when the processor runs the computer program, it executes the aforementioned SAR satellite-based typhoon center positioning method.

[0231] like Figure 4 As shown, the 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 program execution of the present invention. The communication interface can be one or more. The communication interface can use any device, such as a transceiver, for communicating with other devices or a communication network.

[0232] like Figure 4 As shown, the terminal device may further include a communication line. The communication line may include a path for transmitting information between the components.

[0233] Optional, such as Figure 4 As shown, the terminal device may further include a memory. The memory stores a computer program executable by the processor; when the processor executes the computer program, the method provided by the embodiment of the present invention is implemented.

[0234] like Figure 4As shown, the memory may be, but is not limited to, read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions, random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions, electrically erasable programmable read-only memory (EEPROM), 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 capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer. The memory may be independent and connected to the processor via a communication link. Alternatively, the memory may be integrated with the processor.

[0235] Optionally, the computer-executable instructions in the embodiment of the present invention may also be referred to as application program codes, which is not specifically limited in the embodiment of the present invention.

[0236] In a specific implementation, as an embodiment, Figure 4 As shown, the processor may include one or more CPUs, such as Figure 4 CPU0 and CPU1 in.

[0237] In a specific implementation, as an embodiment, Figure 4 As shown, the terminal device may include multiple processors, such as Figure 4 Each of these processors can be a single-core processor or a multi-core processor.

[0238] Based on the same idea, the embodiments of this specification also provide a computer storage medium corresponding to the above embodiments. The computer storage medium stores instructions, and when the instructions are executed, the method in the above embodiments is implemented.

[0239] The above mainly introduces the solution provided by the embodiment of the present invention from the perspective of the interaction between the various modules. It can be understood that, in order to realize the above functions, each module includes a hardware structure and / or software unit corresponding to the execution of each function. It should be easy for those skilled in the art to 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 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 and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0240] The embodiments of the present invention can be divided into functional modules according to the above-mentioned method examples. For example, each functional module can be divided according to each function, or two or more functions can be integrated into a single processing module. The above-mentioned integrated modules can be implemented in the form of hardware or software functional modules. It should be noted that the division of modules in the embodiments of the present invention is illustrative and is only a logical functional division. In actual implementation, other division methods may be used.

[0241] The processor in this specification may also function as a memory. The memory is used to store computer-executable instructions for implementing the solutions of the present invention, and the processor controls the execution of the instructions. The processor is used to execute the computer-executable instructions stored in the memory, thereby implementing the methods provided in the embodiments of the present invention.

[0242] Memory can be, but is not limited to, read-only memory (ROM) or other types of static storage devices capable of storing static information and instructions, random access memory (RAM) or other types of dynamic storage devices capable of storing information and instructions, electrically erasable programmable read-only memory (EEPROM), compact disc read-only memory (CD-ROM) or other optical disk 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 capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer. Memory can be independent and connected to the processor via communication lines. Memory can also be integrated with the processor.

[0243] Optionally, the computer-executable instructions in the embodiment of the present invention may also be referred to as application program codes, which is not specifically limited in the embodiment of the present invention.

[0244] The methods disclosed in the above embodiments of the present invention can be applied to or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by hardware integrated logic circuits in the processor or by software instructions. The above processor may be a general-purpose processor, a digital signal processor (DSP), an ASIC, a field-programmable gate array (FPGA), or other programmable logic device, a discrete gate or transistor logic device, or a discrete hardware component. The methods, steps, and logic block diagrams disclosed in the embodiments of the present invention can be implemented or executed. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the methods disclosed in conjunction with the embodiments of the present invention can be directly implemented and executed by a hardware decoding processor or by a combination of hardware and software modules in the decoding processor. The software modules can be located in a storage medium well-known in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, or registers. The storage medium is located in a memory, and the processor reads information from the memory and, in conjunction with its hardware, completes the steps of the above method.

[0245] Although the present invention has been described herein in conjunction with various embodiments, in the process of implementing the claimed invention, those skilled in the art may understand and implement other variations of the disclosed embodiments by reviewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in the claims. Certain measures are recorded in different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0246] Although the present invention has been described with reference to specific features and embodiments thereof, it will be apparent that various modifications and combinations may be made thereto without departing from the spirit and scope of the invention. Accordingly, this specification and drawings are merely illustrative of the invention as defined by the appended claims and are deemed to cover any and all modifications, variations, combinations or equivalents within the scope of the invention. It will be apparent that various modifications and variations may be made to the present invention by those skilled in the art without departing from the spirit and scope of the invention. Thus, the present invention is intended to include such modifications and variations as fall within the scope of the claims of the present invention and their equivalents.

Claims

1. A typhoon center positioning method based on SAR satellite, characterized in that: Methods include: Acquire basic data of SAR satellites 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 auxiliary data; Performing sea surface wind speed and direction inversion based on the basic data to obtain inversion data; Determining the high wind speed area of ​​the typhoon using the gradient wind equation, the wind profile equation, and the maximum wind speed based on the inversion data; Determine the location range of the typhoon center point based on the cyclonic vortex structure of the typhoon, the vertical vorticity 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; The typhoon center is located with a preset accuracy according to the typhoon center point position range.

2. The typhoon center positioning method based on SAR satellite according to claim 1, characterized in that: The sea surface wind speed and direction are inverted based on the basic data to obtain inversion data, including: Performing image preprocessing on the SAR satellite data, calculating the wind field units according to the requirements of wind field unit division of sea surface wind field products with different resolutions, and dividing them; Using the sea ice edge line auxiliary data, the divided wind units are marked with sea ice; Using geophysical model functions, the wind speed and direction of the sea surface wind field are inverted for both co-polarization wind speed and cross-polarization wind speed. Then, according to the wind unit reference wind direction obtained from the numerical model wind field data, the SAR sea surface wind field inversion results are fuzzy-free to obtain inversion data that meets the requirements.

3. The typhoon center positioning method based on SAR satellite according to claim 2, characterized in that: Using geophysical model functions, the wind speed and direction of the sea surface wind field are inverted for both co-polarization and cross-polarization wind speeds, including: When the wind speed is less than the preset threshold, the sea surface wind direction and observation geometry data are used to invert the sea surface wind speed using the CMOD model of the GMF geophysical model function. The CMOD model is a function model of the sea surface wind speed, sea surface wind direction and radar incident angle. The CMOD model is expressed as: ； in, is the backscattering coefficient, Indicates the relative wind direction, represents empirical parameters, B0, B1, and B2 are functions of sea surface wind speed and 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 inverted using the linear relationship model between the cross-polarization backscatter 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.

4. The typhoon center positioning method based on SAR satellite according to claim 1, characterized in that: Based on the inversion data, the gradient wind equation, wind profile equation and maximum wind speed are used to determine the high wind speed area of ​​the typhoon, including: According to the inversion data, the gradient wind equation is used: ； Determine the radial extent of the high wind speed area; 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, Other external forces in the horizontal direction; Using the wind profile equation: ； Determine the vertical distribution range of high wind speed areas; represents the characteristic wind speed, Indicates 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 maximum wind speed radius, B is the proportional coefficient, and P is the pressure; Determine the maximum wind speed position, take the maximum wind speed position 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 adjust the horizontal range of the high wind speed area in combination with actual wind speed observation data to obtain a typhoon high wind speed area that meets the conditions.

5. The typhoon center positioning method based on SAR satellite according to claim 4, characterized in that: According to the cyclonic vortex structure of the typhoon, the vertical vorticity 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, the position range of the typhoon center point is determined, 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, we get: ； The differential expression of the vertical component of the relative vorticity of the vorticity field is expressed as: ； The differential 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 differential expression of the horizontal divergence of the divergence field is: ； determining the product of the vorticity field and the divergence field as a composite field; According to the vorticity field, the divergence field and the composite field, determining 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 obtaining 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; The center point with the smallest wind speed among the three center points is determined as the potential center point, and the longitude and latitude range of ±0.5° near the potential center point is determined as the typhoon center point position range.

6. The typhoon center positioning method based on SAR satellite according to claim 5, characterized in that: Locating the typhoon center with a preset accuracy according to the typhoon center position range includes: Find the point with the minimum wind speed within the range of the typhoon center point; Different search sizes are selected according to the wind field resolution. For low-resolution wind fields, the wind speed of each wind vector unit in the area near the typhoon center is sorted from small to large using the first search size. The longitude and latitude corresponding to the wind speed are recorded at the same time, and the point with the minimum wind speed is selected as the typhoon center. For high-resolution wind fields, the average wind speed within each search size in the area near the typhoon center is calculated by sliding the second search size: ； Among them, the second search size is larger than the first search size, k is the window size, x, y are the indexes of the matrix A near the typhoon center, i, j are the indexes of the output matrix B, and by recording the longitude and latitude of the starting grid point, the values ​​in the average wind speed matrix B in the area are sorted to determine the grid point with the smallest average wind speed and the corresponding longitude and latitude, and the grid point with the smallest average wind speed is determined as the typhoon center.

7. The typhoon center positioning method based on SAR satellite according to claim 6, characterized in that: The method further comprises: Calculate the radius of the wind circle; The calculation of the wind circle radius includes: Based on the distribution characteristics of wind speed with radius, the wind circle range is divided into two parts according to the wind speed thresholds in different typhoon areas. Calculate the parameter B of the Holland model based on the latitude and longitude of the typhoon center, the maximum wind speed, and the maximum wind speed radius: ； 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 maximum wind speed radius, the maximum wind speed radius 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 within the preset radius with the typhoon center as the origin; Taking the typhoon center as the origin, the wind speed is divided into four quadrants. The wind speeds of observation points within different radii from the typhoon center are calculated to form the typhoon radial wind speed profile and obtain the radius of the wind circle in each quadrant.

8. A typhoon center positioning device based on SAR satellite, characterized in that: The device includes: A basic data determination module is used to obtain basic data of SAR satellites based on 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 auxiliary data; A sea surface wind speed and direction inversion module is used to invert the sea surface wind speed and direction based on the basic data to obtain inversion data; A typhoon high wind speed area determination module is used to determine the typhoon high wind speed area based on the inversion data using the gradient wind equation, the wind profile equation and the maximum wind speed; A typhoon center position range determination module is used to determine the typhoon center position range based on the cyclonic vortex structure of the typhoon, the vertical vorticity 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; The typhoon center determination module is used to locate the typhoon center with a preset accuracy according to the typhoon center point position range.

9. A typhoon center positioning device based on SAR satellite, characterized in that the device include: a memory, a processor, and a communication interface coupled to the processor; The memory stores a computer program executable by the processor; When the processor runs the computer program, it executes the typhoon center positioning method based on SAR satellite according to any one of claims 1 to 7.

10. A computer storage medium, characterized in that The computer storage medium stores instructions, and when the instructions are executed by the processor, the typhoon center positioning method based on SAR satellites according to any one of claims 1 to 7 is implemented.

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