A method and system for detecting tropical cyclones

Abstract

This application discloses a method and system for tropical cyclone detection. The method includes: determining the satellite orbital coverage area based on the activity area of ​​the tropical cyclone and selecting the orbital inclination; synchronously observing the activity area of ​​the tropical cyclone using a dual-band SAR payload to acquire a first-band return signal and a second-band return signal; using the first-band return signal to retrieve an initial estimate of the sea surface wind field, and using the second-band return signal to obtain precipitation distribution and intensity; based on the precipitation distribution and intensity, correcting the initial estimate of the sea surface wind field for precipitation attenuation to obtain corrected tropical cyclone wind field parameters; and transmitting the corrected tropical cyclone wind field parameters back. This method comprehensively improves the accuracy and timeliness of wind field retrieval under severe convective rainfall, overcomes the bottlenecks of insufficient resolution of traditional scatterometers and rain attenuation interference from single-frequency SAR, and meets the integrated operational needs for complete coverage and fine structure of tropical cyclones.

Description

Technical Field

[0001] This invention relates to the fields of aerospace remote sensing and meteorological satellite technology, and in particular to a method and system for detecting tropical cyclones. Background Technology

[0002] A tropical cyclone primarily consists of a relatively calm eye region, a deep convection eyewall, and a spiral convective rainband surrounding the eyewall. Tropical cyclones have a wide coverage area, ranging in diameter from thousands of kilometers to tens of kilometers, and encompass weather processes at multiple scales, such as Rossby waves (scaled to hundreds of kilometers) and their outer spiral rainbands, convective cells (scaled to several kilometers), and turbulent processes (scaled to hundreds of meters). The interactions between these multi-scale processes add significant challenges to the study of tropical cyclone formation, development, and dissipation.

[0003] Currently, satellites used to detect tropical cyclone wind fields include Fengyun-3, Haiyang-2, Zhongfa Oceanographic, and Gaofen-3, with onboard instruments including wind field detection radar, microwave scatterometers, microwave imagers, and synthetic aperture radar (SAR). However, current observation methods such as microwave scatterometers and microwave imagers cannot simultaneously achieve both wide swath width and high spatial resolution, making it difficult to detect low-level wind fields under strong storm and heavy rain conditions. SAR, with its day and night observation capabilities and high resolution, can penetrate the dense cloud systems of typhoons to obtain detailed information about the sea surface, enabling the estimation of tropical cyclone intensity, structure, and motion parameters.

[0004] However, heavy rainfall is prevalent in typhoon areas, interfering with radar backscatter measurements and resulting in a lack of accurate rainfall intensity data, which affects the inversion of high wind speeds under heavy rainfall. Currently, the lack of large-scale, continuous, and high-resolution detection of low-level wind fields and precipitation throughout the entire life cycle of typhoons limits our understanding of the fine structural changes in the low-level wind field of typhoons and the multi-scale physical mechanisms of their coupling with convective rainbands, making it extremely difficult to construct a complete and detailed model of the low-level wind field of typhoons.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a tropical cyclone detection method and system to solve the problems of insufficient resolution of traditional scatterometers and bottlenecks caused by rain attenuation interference of single-frequency SAR in the existing technology, as well as the lack of related technologies for accurate typhoon detection, so as to realize the understanding of the fine structure changes of the low-level wind field of typhoons and its multi-scale physical mechanism of coupling with convective rainbands.

[0007] To achieve the above objectives, the present invention provides a method for detecting tropical cyclones, comprising the following steps:

[0008] S1. Determine the satellite orbital coverage area based on the activity area of ​​the tropical cyclone and select the orbital inclination angle;

[0009] S2. A dual-band SAR payload is used to simultaneously observe the activity area of ​​tropical cyclones and acquire the first-band return signal and the second-band return signal. The dual-band SAR payload includes a first-band for detecting sea surface wind field signals and a second-band for detecting rainfall scattering signals.

[0010] S3. Use the first frequency band return signal to retrieve the initial estimate of the sea surface wind field, and use the second frequency band return signal to obtain the precipitation distribution and intensity.

[0011] S4. Based on the precipitation distribution and intensity, the initial estimate of the sea surface wind field is corrected by precipitation attenuation to obtain the corrected tropical cyclone wind field parameters.

[0012] S5, transmit the corrected tropical cyclone wind field parameters.

[0013] The track inclination angle in S1 is a low inclination angle.

[0014] The first frequency band is the C-band, and the second frequency band is the Ku-band; the C-band is used to penetrate clouds and rain to obtain the sea surface wind field signal, and the Ku-band is used to simultaneously obtain the rainfall scattering signal.

[0015] The method further includes: acquiring wind speed information through a common polarization channel;

[0016] When the backscattering coefficient of the common polarization channel tends to saturate, a cross-polarization channel is used to continue to acquire high wind speed information; wherein, the cross-polarization channel is a VH cross-polarization channel or an HV cross-polarization channel, and the common polarization channel is a VV common polarization channel or an HH common polarization channel.

[0017] The method further includes: determining the development stage of a tropical cyclone based on its maximum central wind speed or classification.

[0018] The imaging swath width and spatial resolution mode are adjusted according to the development stage of the tropical cyclone.

[0019] The method further includes: determining the geographical attributes of the observation area in real time, and switching the observation mode from marine wind field detection mode to land surface observation mode when the observation area is detected to change from sea area to land area.

[0020] The side-looking maneuver of the dual-band SAR payload is used to observe the path of tropical cyclones laterally.

[0021] The method further includes: when the satellite passes over a low-latitude target area, establishing a high-speed laser communication link with a geostationary orbit satellite and sending data, which is then relayed by the geostationary orbit satellite to a ground receiving station located in the mid-to-high latitudes.

[0022] In one embodiment of the present invention, a tropical cyclone detection system is provided, comprising:

[0023] The inclination design unit is used to determine the satellite orbital coverage area and select the orbital inclination angle based on the activity area of ​​tropical cyclones.

[0024] The signal acquisition unit is used to simultaneously observe the activity area of ​​tropical cyclones using a dual-band SAR payload, and acquire the first-band return signal and the second-band return signal; wherein, the dual-band SAR payload includes: a first-band for detecting sea surface wind field signals and a second-band for detecting rainfall scattering signals;

[0025] The estimation unit is used to invert the initial estimate of the sea surface wind field using the first frequency band return signal and to obtain the precipitation distribution and intensity using the second frequency band return signal;

[0026] The correction unit is used to perform precipitation attenuation correction on the initial estimate of the sea surface wind field based on the precipitation distribution and intensity, so as to obtain the corrected tropical cyclone wind field parameters.

[0027] The signal return unit is used to return the corrected tropical cyclone wind field parameters.

[0028] In one embodiment of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the tropical cyclone detection method as described in any of the preceding claims.

[0029] Compared with existing technologies, the tropical cyclone detection method and system of the present invention can comprehensively improve the accuracy and timeliness of wind field inversion under strong convective rainfall, break through the bottlenecks of insufficient resolution of traditional scatterometers and rain attenuation interference of single-frequency SAR, and meet the integrated operational needs of complete coverage and fine structure of tropical cyclones. Attached Figure Description

[0030] Figure 1 This is a flowchart of a tropical cyclone detection method according to an embodiment of the present invention;

[0031] Figure 2 This is a structural diagram of a tropical cyclone detection system according to an embodiment of the present invention;

[0032] Figure 3 This is a statistical overview of the range of tropical cyclone activity from 2015 to 2024;

[0033] Figure 4 This is a revisit efficiency of 710 km at a tilt angle of 33° according to an embodiment of the present invention;

[0034] Figure 5 This refers to the number of tropical cyclones of different severity levels that made landfall in my country according to an embodiment of the present invention. Detailed Implementation

[0035] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0036] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0037] like Figure 1 As shown, a tropical cyclone detection method according to a preferred embodiment of the present invention, such as... Figure 1 As shown, it includes the following steps:

[0038] S1. Determine the satellite orbit coverage area and select the orbital inclination based on the activity area of ​​tropical cyclones. Specifically, tropical cyclones mainly operate in mid-to-low latitude sea areas, and the frequency of formation and activity range of tropical cyclones vary significantly across different latitude zones. This embodiment determines the latitudinal range to be covered by the satellite orbit based on statistical information on historical activity areas of global tropical cyclones, and selects an appropriate orbital inclination accordingly, ensuring that the satellite's nadir trajectory covers the main activity areas of tropical cyclones. Simultaneously, in conjunction with the orbital altitude design, adjust the daily observation frequency of the satellite over the target area to meet the monitoring needs of rapidly changing tropical cyclone processes.

[0039] S2. A dual-band SAR payload is used to simultaneously observe the activity area of ​​tropical cyclones, acquiring return signals in both the first and second bands. The dual-band SAR payload includes a first band for detecting sea surface wind field signals and a second band for detecting precipitation scattering signals. Specifically, in the payload frequency band design, a low-frequency microwave band with weak rain attenuation characteristics is selected as the first band. This band is less affected by rainfall attenuation and can stably acquire sea surface wind field signals under heavy precipitation conditions. Simultaneously, a high-frequency microwave band sensitive to rainfall scattering is selected as the second band. This band has a strong response to raindrop scattering and can be used to capture precipitation signals. Through this dual-band collaborative observation mechanism, the satellite simultaneously acquires both wind field and precipitation information during a single transit, achieving decoupling between sea surface wind field and precipitation.

[0040] S3. The initial estimate of the sea surface wind field is retrieved using the first frequency band return signal, and the precipitation distribution and intensity are obtained using the second frequency band return signal. Specifically, in the data processing stage, the initial estimate of the sea surface wind field is first obtained by retrieving the first frequency band return signal based on the sea surface wind field inversion model. Simultaneously, the precipitation distribution range and intensity information within the observation area are extracted using the raindrop scattering information in the second frequency band return signal.

[0041] S4. Based on the precipitation distribution and intensity, the initial estimate of the sea surface wind field is corrected for precipitation attenuation to obtain the corrected tropical cyclone wind field parameters. Specifically, because the first frequency band is still affected by rainfall attenuation under extreme heavy precipitation conditions, the initial estimate of the sea surface wind field has a deviation. This step uses the precipitation distribution and intensity information obtained from the second frequency band to correct the initial estimate of the sea surface wind field for precipitation attenuation, compensating for the attenuation effect of rainfall on radar signals, thereby obtaining more accurate tropical cyclone wind field parameters.

[0042] S5. Transmit the corrected tropical cyclone wind field parameters. The corrected tropical cyclone wind field parameters are transmitted back to the ground receiving system via satellite communication link for meteorological departments to use for tropical cyclone monitoring and forecasting.

[0043] The tropical cyclone detection method described in the above embodiments of the present invention can comprehensively improve the accuracy and timeliness of wind field inversion under strong convective rainfall, break through the bottlenecks of insufficient resolution of traditional scatterometers and rain attenuation interference of single-frequency SAR, and meet the integrated business needs of complete coverage and fine structure of tropical cyclones.

[0044] In the tropical cyclone detection method described in this embodiment of the invention, preferably, the orbital inclination in step S1 is a low inclination angle. Specifically, in this embodiment, the orbital inclination angle is low. Based on the global cyclone database, which statistically analyzes the latitudinal ranges and activity areas of tropical cyclones, the low-inclination orbit design enables the satellite observation area to cover the activity range covered by most typhoons' life cycles, achieving coverage and revisiting of tropical cyclones in the relevant areas. The orbital inclination angle and altitude are calculated and designed according to the payload's incident angle range and field of view coverage requirements, increasing the daily revisit frequency of the satellite for the target area.

[0045] In the tropical cyclone detection method described in this embodiment of the invention, preferably, the first frequency band is the C-band and the second frequency band is the Ku-band; wherein, the C-band is used to penetrate clouds and rain to obtain the sea surface wind field signal, and the Ku-band is used to simultaneously obtain the rainfall scattering signal. Specifically, the C-band is more sensitive to wind speed and has strong cloud and rain penetration capability, making it very suitable for measuring sea surface wind fields; the Ku-band is more sensitive to raindrop scattering and has a better signal-to-noise ratio, making it suitable for detecting typhoon rainstorms. By employing a C+Ku dual-frequency radar transmitter and receiver, the satellite can simultaneously acquire wind field and rainfall information.

[0046] The tropical cyclone detection method described in this embodiment of the invention, preferably, further includes: when the backscattering coefficient of the common polarization channel tends to saturate, using a cross-polarization channel to continue acquiring high wind speed information; wherein, the cross-polarization channel is a VH cross-polarization channel or an HV cross-polarization channel, and the common polarization channel is a VV common polarization channel or an HH common polarization channel. Specifically, under strong wind conditions, the NRCS of the common polarization VV / HH tends to saturate, while the cross-polarization VH / HV maintains stronger sensitivity to high wind speeds. Therefore, the multi-polarization system containing cross-polarization can expand the dynamic range of wind speed inversion. By introducing a cross-polarization channel, the fully polarized radar can effectively overcome the saturation bottleneck of the common polarization signal under high wind speed conditions, broaden the dynamic range of wind speed inversion, and achieve high-precision measurement of extreme typhoon wind fields. In order to obtain extreme wind speeds, a reasonable polarization mode is selected to enhance the SAR payload's ability to identify the fine structure of the eyewall and effectively identify the foam in the strongest typhoon wind zone, thereby obtaining more realistic and accurate wind field information.

[0047] In a preferred embodiment, during data processing, the initial estimate of the sea surface wind field is first obtained by using the C-band return signal, and then combined with the rainfall distribution and intensity reflected by the Ku-band signal to provide a basis for subsequent correction.

[0048] The tropical cyclone detection method described in this embodiment of the invention, preferably, further includes: determining the development stage of the tropical cyclone based on the maximum central wind speed or classification of the tropical cyclone.

[0049] The imaging swath width and spatial resolution mode are adjusted according to the development stages of the tropical cyclone. Specifically, the development stages of the tropical cyclone include the formation stage, the maturity stage, and the weakening stage. During the formation stage, a wide-swath mode is used to acquire the overall structure of the tropical cyclone. During the maturity stage, a high-resolution mode is used to observe the eyewall and spiral rainbands. During the weakening stage, the swath width is adjusted to track the decay path of the tropical cyclone.

[0050] Ideally, the satellite platform integrates an intelligent scheduling and control system, enabling autonomous adjustment of the SAR payload's operating mode. For example, when the cyclone's range is large, a wide-swath imaging mode is activated to obtain a panoramic view; when the cyclone's intensity increases and its internal structure undergoes drastic changes, a high-resolution mode is switched for detailed observation. The scheduling system can also automatically plan observation schemes based on the stages of the typhoon's life cycle, achieving dynamic optimization of the combination of swath width and resolution. This intelligent scheduling capability ensures that the satellite always monitors typhoons in the optimal mode, not only improving observation efficiency in critical scenarios but also avoiding unnecessary resource consumption.

[0051] The tropical cyclone detection method described in this embodiment of the invention, preferably, further includes: determining the geographical attributes of the observation area in real time based on land-sea boundary data stored in a spaceborne electronic map; and switching the observation mode from ocean wind field detection mode to land surface observation mode when the observation area changes from sea to land. Specifically, through a land-sea boundary identification unit, the land-sea attributes of the observation area are determined in real time based on the spaceborne electronic map, and the ocean / land observation mode is automatically switched to avoid invalid observations of non-target areas and save energy.

[0052] The tropical cyclone detection method described in this embodiment of the invention preferably utilizes the side-looking maneuver of the dual-band SAR payload to perform lateral observation of the tropical cyclone path. Specifically, the left and right side-looking maneuver function of the SAR payload allows the field of view of the SAR payload to deflect left and right relative to the flight direction, thus widening the observation coverage area of ​​the single orbit.

[0053] The tropical cyclone detection method described in this embodiment of the invention, preferably, further includes: establishing a high-speed laser communication link with a geostationary orbit satellite and transmitting data when the satellite passes over a low-latitude target area, and relaying the data to a ground receiving station located in mid-to-high latitudes via the geostationary orbit satellite. Specifically, through a laser relay communication terminal, a data link of at least 1 Gbps can be established with a geostationary orbit satellite or an internet satellite constellation to achieve real-time data downlink in low-latitude areas without ground station coverage.

[0054] A specific embodiment of the present invention also provides a tropical cyclone detection system, such as... Figure 2 As shown, it includes:

[0055] Inclination design unit 201 is used to determine the satellite orbital coverage area and select the orbital inclination angle based on the activity area of ​​the tropical cyclone.

[0056] The signal acquisition unit 202 is used to synchronously observe the activity area of ​​a tropical cyclone using a dual-band SAR payload, and acquire the first frequency band return signal and the second frequency band return signal; wherein, the dual-band SAR payload includes: a first frequency band for detecting sea surface wind field signals and a second frequency band for detecting rainfall scattering signals;

[0057] The estimation unit 203 is used to invert the initial estimate of the sea surface wind field using the first frequency band return signal and to obtain the precipitation distribution and intensity using the second frequency band return signal;

[0058] The correction unit 204 is used to perform precipitation attenuation correction on the initial estimate of the sea surface wind field based on the precipitation distribution and intensity, so as to obtain the corrected tropical cyclone wind field parameters.

[0059] The signal feedback unit 205 is used to transmit the corrected tropical cyclone wind field parameters.

[0060] In one specific embodiment of the present invention, a low-inclination orbit is selected specifically to serve the needs of tropical cyclone observation. For example... Figure 3 As shown, statistical analysis of global tropical cyclone tracks from 2015 to 2024 reveals that the vast majority of cyclone activity lies within 43° north and south latitude. Comparing the orbital revisit efficiency within the 0-45° inclination range, as... Figure 4 The 33° inclination and 710.22 km altitude shown are optimal for revisiting. Considering the small far-end incident angle, which is beneficial for improving wind field inversion accuracy, and the short revisit period, which is beneficial for typhoon dynamic monitoring, a 33° low-inclination orbit at an altitude of 710.22 km is preferred to ensure that the number of revisits per day within 43° north and south latitude is no less than 4, meeting the needs of monitoring rapid typhoon changes. To ensure that the predetermined ground coverage zone is maintained on this inclined orbit for a long period of time, this invention adopts an autonomous orbit maintenance strategy, configuring a micro-sized ion electric thruster on the platform to periodically correct orbital decay and drift, controlling the orbital altitude drift rate within ±2 km / year. Through this orbit maintenance system, the satellite's coverage area and transit time over tropical cyclone regions are kept stable during many years of operation.

[0061] Preferably, the SAR payload of this invention has been specifically optimized for tropical cyclone detection, with innovations in operating frequency band, imaging mode, calibration accuracy, resolution, and swath width. Firstly, a C+Ku dual-frequency combination is adopted in the frequency band design. The C band (e.g., center frequency 5.3 GHz) is highly sensitive to wind speed and has strong cloud and rain penetration capabilities, making it ideal for measuring sea surface wind fields; the C-band is the ideal band for detecting sea surface wind speed. The Ku band (e.g., center frequency 13.6 GHz) is more sensitive to raindrop scattering and has a better signal-to-noise ratio (SNR), making it suitable for detecting typhoon and rainstorm conditions. Using a C+Ku dual-frequency radar transmitter and receiver, the satellite can simultaneously acquire wind field and rainfall information. During data processing, the initial estimate of the sea surface wind field is first inverted using the C-band return signal, and then the rainfall distribution and intensity reflected by the Ku-band signal are combined to correct the wind field results, thereby significantly improving the accuracy of wind speed inversion under heavy rain conditions.

[0062] Preferably, in this embodiment of the invention, the diameters of tropical cyclones of different grades (Table 1) and the number of tropical cyclones of different grades making landfall in my country from 2000 to 2022 are as follows:

[0063] Table 1. Types and diameters of tropical cyclones

[0064] Tropical Cyclone Types Cyclone diameter (km) Wind speed range (m / s) Frequency of occurrence (times / year) Super Typhoon Φ1000—3000 Level 16 and above, >51 1~2 Strong typhoon / typhoon Φ500—1000 Levels 12-15, 32.7-50.9 6~12 Severe tropical storm Φ300—500 Levels 10-11, 24.5-32.6 3~6 Tropical storm Φ100—300 Levels 8-9, 17.2-24.4 10~20 Tropical Depression Less than Φ100 Levels 6-7, 10.8-17.1 50~100

[0065] like Figure 5 As shown, historical statistics indicate that super typhoons with a range greater than 1000 km account for only 1.4% of all typhoons. Therefore, a 1000 km swath design can cover 99% of typhoon conditions, combining practicality and engineering feasibility.

[0066] Preferably, the SAR payload of this embodiment supports multi-mode resolution and swath width combinations. To capture small-scale structures within typhoons, such as secondary circulation vortices with diameters of 1–10 kilometers, this invention preferably uses a radar capable of achieving a ground resolution of approximately 10 meters in high-resolution mode. Since a single imaging session cannot simultaneously achieve both the highest resolution and the widest swath width, this invention employs intelligent scheduling to switch between different modes, allowing for the use of appropriate imaging parameters at different stages of typhoon development.

[0067] To ensure quantitative remote sensing accuracy, the SAR payload system of this invention emphasizes calibration accuracy and sensitivity design. The radar's transmit power, antenna aperture, and receiver specifications have been optimized to maintain a sufficient signal-to-noise ratio at a 10-meter resolution, preventing signal saturation when detecting extreme wind speeds at the sea surface. Simultaneously, the payload possesses comprehensive internal calibration and external verification mechanisms, achieving an absolute radiometric calibration accuracy better than 1 dB, ensuring that data from different polarizations and frequency bands can be uniformly calibrated for inversion calculations.

[0068] Under strong wind (typhoon eyewall) conditions, the NRCS of co-polarized VV / HH signals tends to saturate; while cross-polarized (VH / HV) signals maintain stronger sensitivity to high wind speeds. Therefore, a multi-polarization system "including cross-polarization" can expand the dynamic range of wind speed retrieval. By introducing cross-polarized (VH / HV) channels, fully polarimetric radar can effectively overcome the saturation bottleneck of co-polarized (VV / HH) signals under high wind speed conditions, broaden the dynamic range of wind speed retrieval, and achieve high-precision measurement of extreme typhoon wind fields.

[0069] Preferably, the SAR satellite platform of this invention is equipped with a left and right side-looking maneuvering mechanism. Combined with the SAR antenna incident angle, this allows the satellite to achieve a visible imaging bandwidth of 2000 km when passing over a target area through side-swinging. The integrated intelligent scheduling and control system on the satellite platform enables autonomous adjustment of the SAR payload's operating mode. For example, when the cyclone range is large, a wide-swath imaging mode is activated to obtain a panoramic view; when the cyclone intensity increases and its internal structure undergoes drastic changes, a high-resolution mode is switched for detailed observation. The scheduling system can also automatically plan observation schemes according to the stages of the typhoon's life cycle (e.g., reducing observation frequency during the formation phase and increasing monitoring density during the maturity and weakening phases), achieving dynamic optimization of the swath width and resolution combination. This intelligent scheduling capability ensures that the satellite always monitors typhoons in the optimal mode, not only improving observation efficiency in critical scenarios but also avoiding unnecessary resource consumption.

[0070] Preferably, the SAR satellite platform of the present invention includes a land-sea boundary identification unit, which determines the land-sea attributes of the observation area in real time based on the onboard electronic map and automatically switches between ocean / land observation modes to avoid invalid observations of non-target areas and save energy.

[0071] Preferably, the SAR satellite platform of this invention integrates a laser relay communication terminal, requiring a laser link rate of 1Gbps or higher to handle the large data volume generated by wide-swath imaging. This terminal can establish a high-speed laser communication link with a geostationary satellite when the satellite passes over a low-latitude target area, transmitting SAR observation data to the geostationary satellite in real time, and then relaying it via the geostationary satellite to domestic ground receiving stations located in mid-to-high latitudes. This means that meteorological departments can obtain typhoon wind field and rainfall information from satellite observations almost in real time for forecasting and decision-making, greatly enhancing the effectiveness of operational applications.

[0072] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the tropical cyclone detection method as described in any of the above embodiments.

[0073] The tropical cyclone detection method provided by this invention achieves its observation objectives through an overall design scheme for a meteorological SAR satellite system centered on a low-inclination, wide-coverage orbit, a dual-frequency, multi-polarization SAR payload, and an intelligent maneuvering platform. The low-inclination orbit design increases the revisit frequency for mid- and low-latitude typhoon regions; the dual-frequency, multi-polarization system decouples sea surface wind fields from rainfall, improving the measurement accuracy of high wind speeds under heavy rainfall conditions; and the combination of intelligent task scheduling and high-speed laser data relay technology enhances the effective coverage of observations, meeting the needs for refined tropical cyclone monitoring. This constructs a complete, intelligent, and efficient tropical cyclone detection satellite capability system, enabling the satellite to stably and efficiently complete typhoon detection missions under complex marine meteorological conditions.

[0074] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for detecting tropical cyclones, characterized in that, Includes the following steps: S1. Determine the satellite orbital coverage area based on the activity area of ​​the tropical cyclone and select the orbital inclination angle; S2. A dual-band SAR payload is used to simultaneously observe the activity area of ​​tropical cyclones and acquire the first-band return signal and the second-band return signal. The dual-band SAR payload includes a first-band for detecting sea surface wind field signals and a second-band for detecting rainfall scattering signals. S3. Use the first frequency band return signal to retrieve the initial estimate of the sea surface wind field, and use the second frequency band return signal to obtain the precipitation distribution and intensity. S4. Based on the precipitation distribution and intensity, the initial estimate of the sea surface wind field is corrected by precipitation attenuation to obtain the corrected tropical cyclone wind field parameters. S5, transmit the corrected tropical cyclone wind field parameters.

2. The tropical cyclone detection method according to claim 1, characterized in that: The track inclination angle in S1 is a low inclination angle.

3. The tropical cyclone detection method according to claim 1, characterized in that: The first frequency band is the C-band, and the second frequency band is the Ku-band; wherein, the C-band is used to penetrate clouds and rain to obtain the sea surface wind field signal, and the Ku-band is used to synchronously obtain the rainfall scattering signal.

4. The tropical cyclone detection method according to claim 1, characterized in that, The method further includes: Wind speed information is obtained through a common polarization channel; When the backscattering coefficient of the common polarization channel tends to saturate, a cross-polarization channel is used to continue to acquire high wind speed information; wherein, the cross-polarization channel is a VH cross-polarization channel or an HV cross-polarization channel, and the common polarization channel is a VV common polarization channel or an HH common polarization channel.

5. The tropical cyclone detection method according to claim 1, characterized in that, The method further includes: The development stage of a tropical cyclone is determined based on its maximum central wind speed or classification. The imaging swath width and spatial resolution mode are adjusted according to the development stage of the tropical cyclone.

6. The tropical cyclone detection method according to claim 1, characterized in that, The method further includes: determining the geographical attributes of the observation area in real time, and switching the observation mode from marine wind field detection mode to land surface observation mode when the observation area is detected to change from sea area to land area.

7. The tropical cyclone detection method according to claim 1, characterized in that: Lateral observations of tropical cyclone paths are performed using the side-looking maneuver of the dual-band SAR payload.

8. The tropical cyclone detection method according to claim 1, characterized in that, The method further includes: when the satellite passes over a low-latitude target area, establishing a high-speed laser communication link with a geostationary orbit satellite and sending data, which is then relayed by the geostationary orbit satellite to a ground receiving station located in the mid-to-high latitudes.

9. A tropical cyclone detection system, characterized in that, include: The inclination design unit is used to determine the satellite orbital coverage area and select the orbital inclination angle based on the activity area of ​​tropical cyclones. The signal acquisition unit is used to simultaneously observe the activity area of ​​tropical cyclones using a dual-band SAR payload, and acquire the first-band return signal and the second-band return signal; wherein, the dual-band SAR payload includes: a first-band for detecting sea surface wind field signals and a second-band for detecting rainfall scattering signals; The estimation unit is used to invert the initial estimate of the sea surface wind field using the first frequency band return signal and to obtain the precipitation distribution and intensity using the second frequency band return signal; The correction unit is used to perform precipitation attenuation correction on the initial estimate of the sea surface wind field based on the precipitation distribution and intensity, so as to obtain the corrected tropical cyclone wind field parameters. The signal return unit is used to return the corrected tropical cyclone wind field parameters.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the tropical cyclone detection method as described in any one of claims 1 to 8.

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