Island-crossing hollow typhoon objective identification method based on remote sensing product

Abstract

The invention belongs to the technical field of remote sensing, and provides an island-crossing hollow typhoon objective identification method based on a remote sensing product. Comprising the steps of typhoon center movement track and maximum wind speed radius collection, island-crossing typhoon judgment, typhoon center position collection, rainfall rate data and equivalent black body temperature data determination, typhoon total time recording, typhoon time and hollow time initialization, typhoon kernel area and typhoon peripheral area division, typhoon kernel area data calculation, typhoon center position calculation and typhoon center position calculation. Calculating data in a typhoon peripheral area, judging a preset judgment condition and judging a preset hollow judgment threshold value; according to the method, the typhoon hollow time is processed by using the preset judgment condition, the island-crossing hollow typhoon is identified, the island-crossing hollow typhoon identification process is simplified, the island-crossing hollow typhoon identification accuracy and speed are improved, and a research basis is provided for multi-sample statistical analysis and prediction of wind and rain distribution in the island-crossing hollow typhoon.

Description

Technical Field

[0001] The present invention relates to the field of remote sensing technology, and in particular to an objective identification method for island-passing hollow typhoons based on remote sensing products. Background Art

[0002] Accurately forecasting the locations of heavy rainfall within the outer circulation of a hollow typhoon passing through an island remains a significant challenge for current typhoon forecasters. This has long been a difficult area of typhoon forecasting and a hot topic for studying the structural changes in the hollowing of islands as typhoons pass through them and the underlying mechanisms. Studying the hollowing structure and heavy rainfall locations of typhoons passing through islands is a key scientific issue in island-passing typhoon research and an important strategy for improving forecast accuracy and mitigating typhoon disasters.

[0003] Currently, the identification of hollow typhoons still relies on subjective judgment and lacks objective identification methods. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the purpose of the present invention is to provide an objective identification method for hollow typhoons passing through islands based on remote sensing products, so as to solve the problem that the existing identification of hollow typhoons relies on subjective judgment.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] Objective identification methods for typhoons with hollow cores passing over islands based on remote sensing products include:

[0007] Collect the moving track of the typhoon center and the maximum wind speed radius of the target typhoon;

[0008] When the moving track of the typhoon center passes through the target island or the land-sea boundary of the target island, the target typhoon is determined to be an island-passing typhoon;

[0009] Collect the typhoon center position 24 hours before and 36 hours after the typhoon lands on the island;

[0010] Determine the precipitation rate data and equivalent blackbody temperature data of the typhoon passing through the island according to the position of the typhoon center;

[0011] The length of the record of the typhoon center position within 24 hours before and 36 hours after landing on the island is recorded as the total typhoon duration;

[0012] Initialize the typhoon time and hollow time to 1 and 0 respectively;

[0013] When the typhoon duration is less than or equal to the total typhoon duration, reading the precipitation rate distribution and convection distribution corresponding to the typhoon duration according to the precipitation rate data of the typhoon passing through the island and the equivalent blackbody temperature data;

[0014] Converting the precipitation rate distribution and the convection distribution into a polar coordinate system centered on the typhoon center;

[0015] The area within a radius of three times the maximum wind speed from the center of the typhoon at the typhoon time is determined as the typhoon core area, and the area between three times and ten times the maximum wind speed radius from the center of the typhoon is determined as the typhoon peripheral area;

[0016] Calculating the maximum core precipitation rate, the minimum core equivalent blackbody temperature, and the first polar coordinate radius and the third polar coordinate radius corresponding to the maximum core precipitation rate and the minimum core equivalent blackbody temperature in the typhoon core region;

[0017] Calculating the outer maximum precipitation rate, the outer minimum equivalent blackbody temperature, and the second polar coordinate radius and the fourth polar coordinate radius corresponding to the outer maximum precipitation rate and the outer minimum equivalent blackbody temperature, respectively, within the outer region of the typhoon;

[0018] When the maximum precipitation rate of the core, the minimum blackbody temperature of the core, the maximum precipitation rate of the periphery, the minimum blackbody temperature of the periphery, and the first to fourth polar coordinate radii meet the preset judgment conditions, the hollow time is increased by 1;

[0019] The typhoon time is increased by 1;

[0020] When the typhoon time is less than or equal to the total typhoon time, return to step "when the typhoon time is less than or equal to the total typhoon time, reading the precipitation rate distribution and convection distribution corresponding to the typhoon time according to the precipitation rate data of the passing typhoon and the equivalent blackbody temperature data";

[0021] When the typhoon time is greater than the total typhoon time, if the ratio of the hollow time to the total typhoon time exceeds the preset hollow judgment threshold, the typhoon passing the island is determined to be a hollow typhoon passing the island; otherwise, the typhoon passing the island is determined to be a non-hollow typhoon.

[0022] Preferably, the expression of the preset judgment condition includes:

[0023] P out -P in ≥M, R1 out -R1 in ≥X, TBB in -TBB out ≥N, R2 out -R2 in ≥Y;

[0024] Among them, P out 、P inare the maximum precipitation rate of the periphery and the maximum precipitation rate of the core respectively; R1 out 、R1 in are the second polar coordinate radius and the first polar coordinate radius respectively; TBB out 、TBB in are the minimum blackbody temperature of the periphery and the minimum blackbody temperature of the core respectively; R2 out 、R2 in are the fourth polar radius and the third polar radius respectively; M is the lower limit of the precipitation rate difference; X is the lower limit of the difference between the second polar radius and the first polar radius; N is the lower limit of the difference in equivalent blackbody temperature; Y is the lower limit of the difference between the fourth polar radius and the third polar radius.

[0025] The present invention discloses the following technical effects:

[0026] The present invention provides an objective identification method for hollow typhoons passing through an island based on remote sensing products, which solves the problem that the existing hollow typhoon identification relies on subjective judgment and realizes the automatic identification of hollow typhoons. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic diagram of the objective identification process of a hollow typhoon passing through an island based on remote sensing products provided in an embodiment of the present invention;

[0029] Figure 2 A flow chart of the hollow typhoon identification module provided in an embodiment of the present invention;

[0030] Figure 3 Schematic diagram of an objective identification system for island-passing hollow typhoons based on remote sensing products provided in an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of typhoon path information of a hollow typhoon A passing through an island provided by an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the horizontal distribution of typhoon TBB before and after passing the island provided by an embodiment of the present invention. Figure 5 (a) is a schematic diagram of the horizontal distribution of Typhoon TBB at a certain moment before passing the island. Figure 5 (b) is a schematic diagram of the horizontal distribution of Typhoon TBB at a certain moment after passing the island;

[0033] Figure 6 A schematic diagram showing the evolution of the minimum TBB radial distribution of Typhoon A over time, provided in an embodiment of the present invention;

[0034] Figure 7 A schematic diagram of the evolution of the radial distribution of the maximum precipitation rate of Typhoon A over time provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] The purpose of the present invention is to provide an objective identification method for hollow typhoons passing through an island based on remote sensing products, so as to solve the problem that the existing identification of hollow typhoons relies on subjective judgment.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] Figure 1 A schematic diagram of the objective identification process of a hollow typhoon passing through an island based on remote sensing products provided in an embodiment of the present invention. Figure 2 The flow chart of the hollow typhoon identification module provided by the embodiment of the present invention is as follows: Figure 1 and Figure 2 As shown, the present invention provides an objective identification method for island-passing hollow typhoons based on remote sensing products, including:

[0039] Step 100: Collect the typhoon center movement trajectory and maximum wind speed radius of the target typhoon;

[0040] Step 200: When the typhoon center moving track passes through the target island or the land-sea boundary of the target island, the target typhoon is determined to be an island-passing typhoon;

[0041] Step 300: collecting the typhoon center position 24 hours before and 36 hours after the typhoon lands on the island;

[0042] Step 400: determining the precipitation rate data and the equivalent blackbody temperature data of the typhoon passing through the island according to the typhoon center position;

[0043] Step 500: Record the length of the typhoon center position within 24 hours before landing on the island and within 36 hours after landing on the island as the total typhoon duration;

[0044] Step 600: Initialize the typhoon time and the hollow time to 1 and 0 respectively;

[0045] Step 700: When the typhoon duration is less than or equal to the total typhoon duration, reading the precipitation rate distribution and convection distribution corresponding to the typhoon duration based on the precipitation rate data of the passing typhoon and the equivalent blackbody temperature data;

[0046] Step 800: converting the precipitation rate distribution and the convection distribution into a polar coordinate system centered on the typhoon center;

[0047] Step 900: Determine the area within three times the maximum wind speed radius from the typhoon center at the typhoon time as the typhoon core area, and the area between three times and ten times the maximum wind speed radius from the typhoon center as the typhoon peripheral area;

[0048] Step 1000: Calculate the maximum core precipitation rate, the minimum core equivalent blackbody temperature, and the first polar coordinate radius and the third polar coordinate radius corresponding to the maximum core precipitation rate and the minimum core equivalent blackbody temperature in the typhoon core region;

[0049] Step 1100: Calculate the maximum precipitation rate and the minimum blackbody temperature in the outer region of the typhoon, as well as the second polar coordinate radius and the fourth polar coordinate radius corresponding to the maximum precipitation rate and the minimum blackbody temperature, respectively.

[0050] Step 1200: When the maximum precipitation rate of the core, the minimum equivalent blackbody temperature of the core, the maximum precipitation rate of the periphery, the minimum equivalent blackbody temperature of the periphery, and the first to fourth polar coordinate radii meet preset judgment conditions, the hollow time is increased by 1;

[0051] Step 1300: The typhoon time is incremented by 1;

[0052] Step 1400: When the typhoon duration is less than or equal to the total typhoon duration, return to step "When the typhoon duration is less than or equal to the total typhoon duration, reading the precipitation rate distribution and convection distribution corresponding to the typhoon duration based on the precipitation rate data of the passing typhoon and the equivalent blackbody temperature data";

[0053] Step 1500: When the typhoon time is greater than the total typhoon time, if the ratio of the hollow time to the total typhoon time exceeds the preset hollow judgment threshold, the typhoon passing the island is determined to be a hollow typhoon passing the island; otherwise, the typhoon passing the island is determined to be a non-hollow typhoon.

[0054] Specifically, the expressions of the preset judgment conditions include:

[0055] P out -P in ≥M, R1out -R1 in ≥X, TBB in -TBB out ≥N, R2 out -R2 in ≥Y;

[0056] Among them, P out 、P in are the maximum precipitation rate of the periphery and the maximum precipitation rate of the core respectively; R1 out 、R1 in are the second polar coordinate radius and the first polar coordinate radius respectively; TBB out 、TBB in are the minimum blackbody temperature of the periphery and the minimum blackbody temperature of the core respectively; R2 out 、R2 in are the fourth polar radius and the third polar radius respectively; M is the lower limit of the precipitation rate difference; X is the lower limit of the difference between the second polar radius and the first polar radius; N is the lower limit of the difference in equivalent blackbody temperature; Y is the lower limit of the difference between the fourth polar radius and the third polar radius.

[0057] refer to Figure 3 This embodiment proposes an objective identification system for typhoons passing through islands based on remote sensing products, which mainly includes:

[0058] 1) Typhoon basic data acquisition module:

[0059] This module determines the typhoon center location (Lon, Lat) and maximum wind radius (RMW) based on time. Typhoon center location (Lon, Lat) and RMW data can be obtained from the International BestTrack Archive for Climate Stewardship (IBTrACS), which contains extensive tropical cyclone information (latitude and longitude of the center, maximum wind speed, RMW, etc.) with a 3-hour resolution. RMW refers to the distance between the location where the typhoon's maximum circulation wind speed occurs and the typhoon center.

[0060] 2) Typhoon Identification Module:

[0061] This module uses the typhoon center location (Lon, Lat) provided by the Typhoon Basic Data Acquisition Module and the island's land and sea boundaries to determine whether a typhoon is an island-passing typhoon. A typhoon is identified as an island-passing typhoon if its center location (Lon, Lat) is located on an island or on a land-sea boundary.

[0062] 3) Precipitation data acquisition module:

[0063] Based on the passing typhoon information provided by the passing typhoon identification module, the typhoon center position and corresponding time within 60 hours (24 hours before and 36 hours after the passing typhoon lands) are selected. This information is used to obtain satellite remote sensing precipitation rate data near the passing typhoon. For example, GPM IMERG v6 precipitation data has a horizontal resolution of 0.1°×0.1°. The Global Precipitation Mission (GPM) is an international satellite mission that utilizes multiple sensors, multiple satellites, and multiple algorithms, combined with satellite networks and rain gauge retrievals, to obtain higher-precision precipitation data. IMERG (Integrated Multi-satellite Retrievals for GPM) is an algorithm for generating GPM's third-level products. It combines data from all GPM passive microwave instruments to provide rainfall estimates, providing global microwave-based rain and snow data products within a 3-hour timeframe and microwave-infrared-based rain and snow data within a 30-hour timeframe.

[0064] 4) Convection data acquisition module:

[0065] Similar to the precipitation data acquisition module, the typhoon's center position within the 60-hour period (24 hours before and 36 hours after the typhoon's landfall) and the satellite remote sensing equivalent blackbody temperature (TBB) near the typhoon during these periods are selected. For example, the geostationary satellite data (GridSat-B1) provides CDR-quality infrared window (IRWIN) channel (near 11μm) TBB data (Gridded Satellite ISCCP B1 Observations, GridSat-B1) with a horizontal resolution of 0.07°×0.07°.

[0066] 5) Hollow typhoon identification module:

[0067] S1: Read the basic data of a typhoon passing through the island, traverse the typhoon center (Lon, Lat) and RMW data, and record the typhoon center record length within 60 hours (24 hours before and 36 hours after the typhoon lands on the island) as the total typhoon time T;

[0068] S2: initial typhoon time i = 1; hollow time k = 0;

[0069] S3: When i <= T, read the precipitation rate distribution and TBB distribution at time i, and convert the precipitation rate distribution and TBB distribution in the rectangular coordinate system into a polar coordinate system with the typhoon center as the coordinate origin. The area within 3 times the RMW is considered to be the typhoon core area, and the area outside is the typhoon periphery area. Calculate the maximum precipitation rate P in the area within 3 times the RMW in and its corresponding polar coordinate radius R1 in, and calculate the maximum precipitation rate P for the area outside 3 times the RMW and within 10 times the RMW out and its corresponding polar coordinate radius R1 out Calculate the minimum blackbody temperature TBB within 3 times RMW in and its corresponding polar coordinate radius R2 in , and calculate the minimum equivalent blackbody temperature TBB in the area from 3 times RMW to 10 times RMW out and its corresponding polar coordinate radius R2 out .

[0070] S4: The period when the precipitation and convection in the outer area of the typhoon are stronger than that in the inner core area is the hollow period, that is, when P out -P in ≥M, R1 out -R1 in ≥X, TBB in -TBB out ≥N, R2 out -R2 in ≥Y, when hollow, times k=k+1.

[0071] S5: Typhoon time i = i + 1.

[0072] S6: When i <= T, repeat S3 to S5 in sequence. When i > T, determine whether the ratio of hollow-core events to total typhoon events (k / T) exceeds a threshold value, L. If (k / T) ≥ L, the passing typhoon is identified as a hollow-core typhoon; otherwise, it is a non-hollow-core typhoon.

[0073] refer to Figure 4 and Figure 5 Typhoon A moved northwestward and landed in the southern part of an island. It reached its peak intensity when it landed, with a maximum wind speed of 31m / s ( Figure 4 ).like Figure 4 It can be seen that the hollow phenomenon occurred 14 times from 24 hours before Typhoon A landed on an island to 36 hours after landing on an island. Among them, there was a phenomenon of heavy rainfall transferring from the outer area to the inner core area 12 hours before landing, but the hollow structure was restored again after passing the island. Figure 5 It can be seen that the low TBB value areas before and after Typhoon A passed the island all appeared on the southwest side of the typhoon's outer area, that is, strong convection developed in the typhoon's outer area, showing a hollow feature of "strong convection in the outer area and weak convection in the inner core area". Figure 5 (a) Horizontal distribution of Typhoon TBB at a certain moment before passing the island (shaded), where the blue dot is the typhoon center, the blue circle is the boundary between the inner core and the outer area, and the black circle is the boundary between the outer area and the environment; Figure 5 (b) shows the horizontal distribution of Typhoon TBB at a certain moment after passing the island (shaded).

[0074] refer to Figure 6 and Figure 7 In order to more clearly show the hollowing phenomenon of typhoons, Figure 6 The temporal evolution of the minimum TBB radial distribution. From -20 to -10 a.m. (20:00 to 10:00 before landfall), the typhoon's severe convection occurred in the outer regions of the typhoon, reaching its peak at -12:00 (12:00 before landfall), with a noticeable hollowing phenomenon occurring during this period. From -10 to 00 a.m. (10:00 to landfall), the typhoon's severe convection shifted toward the inner core, primarily concentrated around 2-3 times the RMW, interrupting the hollowing phenomenon. From 0 to 20 a.m. (from landfall to 20:00 after landfall), the typhoon's severe convection shifted toward the outer regions, primarily concentrated around 4-8 times the RMW, and the hollowing phenomenon returned. Figure 7 The temporal evolution of the radial distribution of the maximum precipitation rate is shown in Figure 1. It can be seen that the temporal evolution of the radial distribution of the maximum precipitation rate is largely consistent with the radial distribution of convection. At -12:00, precipitation reached its peak in the outer regions before landfall. From -10:00 to 0:00, the typhoon's heavy precipitation was primarily concentrated around 2-3 times the RMW. From 0:00 to 20:00, the typhoon's maximum precipitation rate reached its highest point, with heavy precipitation primarily concentrated around 4-8 times the RMW.

[0075] The beneficial effects of the present invention are as follows:

[0076] The present invention processes the hollow time by utilizing preset judgment conditions, thereby realizing automatic identification of hollow typhoons passing over an island and improving the accuracy of hollow typhoon identification.

[0077] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0078] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An objective identification method for typhoons passing through islands based on remote sensing products is characterized by: include: Collect the moving track of the typhoon center and the maximum wind speed radius of the target typhoon; When the moving track of the typhoon center passes through the target island or the land-sea boundary of the target island, the target typhoon is determined to be an island-passing typhoon; Collect the typhoon center position 24 hours before and 36 hours after the typhoon lands on the island; Determine the precipitation rate data and equivalent blackbody temperature data of the typhoon passing through the island according to the position of the typhoon center; The length of the record of the typhoon center position within 24 hours before and 36 hours after landing on the island is recorded as the total typhoon duration; Initialize the typhoon time and hollow time to 1 and 0 respectively; When the typhoon duration is less than or equal to the total typhoon duration, reading the precipitation rate distribution and convection distribution corresponding to the typhoon duration according to the precipitation rate data of the typhoon passing through the island and the equivalent blackbody temperature data; Converting the precipitation rate distribution and the convection distribution into a polar coordinate system centered on the typhoon center; The area within a radius of three times the maximum wind speed from the center of the typhoon at the typhoon time is determined as the typhoon core area, and the area between three times and ten times the maximum wind speed radius from the center of the typhoon is determined as the typhoon peripheral area; Calculating the maximum core precipitation rate, the minimum core equivalent blackbody temperature, and the first polar coordinate radius and the third polar coordinate radius corresponding to the maximum core precipitation rate and the minimum core equivalent blackbody temperature in the typhoon core region; Calculating the outer maximum precipitation rate, the outer minimum equivalent blackbody temperature, and the second polar coordinate radius and the fourth polar coordinate radius corresponding to the outer maximum precipitation rate and the outer minimum equivalent blackbody temperature, respectively, within the outer region of the typhoon; When the maximum precipitation rate of the core, the minimum blackbody temperature of the core, the maximum precipitation rate of the periphery, the minimum blackbody temperature of the periphery, and the first to fourth polar coordinate radii meet the preset judgment conditions, the hollow time is increased by 1; The typhoon time is increased by 1; When the typhoon time is less than or equal to the total typhoon time, return to step "When the typhoon time is less than or equal to the total typhoon time, reading the precipitation rate distribution and convection distribution corresponding to the typhoon time based on the precipitation rate data of the passing typhoon and the equivalent blackbody temperature data"; When the typhoon time is greater than the total typhoon time, if the ratio of the hollow time to the total typhoon time exceeds the preset hollow judgment threshold, the typhoon passing the island is determined to be a hollow typhoon passing the island; otherwise, the typhoon passing the island is determined to be a non-hollow typhoon.

2. The objective identification method of a hollow typhoon passing through an island based on remote sensing products according to claim 1 is characterized in that: The expressions of the preset judgment conditions include: P out -P in ≥M、R1 out -R1 in ≥X、TBB in -TBB out ≥N、R2 out -R2 in ≥Y; Among them, P out 、P in are the maximum precipitation rate of the periphery and the maximum precipitation rate of the core respectively; R1 out 、R1 in are the second polar coordinate radius and the first polar coordinate radius respectively; TBB out 、TBB in are the minimum blackbody temperature of the periphery and the minimum blackbody temperature of the core respectively; R2 out 、R2 in are the fourth polar radius and the third polar radius respectively; M is the lower limit of the precipitation rate difference; X is the lower limit of the difference between the second polar radius and the first polar radius; N is the lower limit of the difference in equivalent blackbody temperature; Y is the lower limit of the difference between the fourth polar radius and the third polar radius.

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