A GNSS wave inversion method compensating for dynamic draft offset of a buoy

Abstract

The present application relates to the technical field of ocean observation, and discloses a GNSS wave inversion method for compensating dynamic draft deviation of a buoy, comprising the following steps: S1, GNSS high-frequency observation data acquisition and preprocessing stage; S2, buoy vertical dynamics modeling stage; S3, dynamic draft deviation characteristic analysis stage; S4, frequency domain response amplitude operator correction stage; S5, wave condition adaptive correction stage; S6, wave parameter inversion and quality evaluation stage; the present application establishes a buoy vertical inertia-buoyancy-damping dynamics model, quantitatively describes the relationship between the buoy dynamic draft deviation and the wave motion for the first time from the physical mechanism level, calculates the dynamic draft deviation amount by epoch, and compensates it into the GNSS measurement results, eliminates the systematic deviation caused by the buoy inertia effect, and reduces the inversion error of the significant wave height from 8% to 15% before correction to within 3%.

Description

Technical Field

[0001] This invention relates to the field of marine observation technology, and in particular to a GNSS wave inversion method for compensating for dynamic draft shift of buoys. Background Technology

[0002] GNSS buoy wave observation technology has been widely used in nearshore wave monitoring due to its advantages such as flexible deployment, low cost and ability to acquire directional spectrum. This technology acquires the time series of the three-dimensional position of the antenna by installing a GNSS receiver on the top of the buoy at a sampling rate of 1~10Hz, and then retrieves wave parameters such as effective wave height Hs, mean period Tz and wave direction through spectral analysis.

[0003] The basic assumption of existing GNSS buoy wave inversion methods is that the buoy can perfectly track the sea surface movement, that is, the vertical displacement of the GNSS antenna is equal to the vertical displacement of the sea surface waves. Under this assumption, the sea surface height is obtained by subtracting the static draft and the antenna installation height from the antenna height. This assumption is approximately valid under small wave conditions, but it will introduce significant errors under medium to large wave conditions.

[0004] As a floating body, the motion of a buoy in waves is subject to the combined effects of inertial force, buoyancy restoring force, fluid damping force, and wave excitation force. The heaving motion of a buoy is essentially a forced vibration system, and its motion response depends on the relationship between the natural frequency of the buoy and the wave frequency. When the wave frequency is close to or exceeds the natural frequency of the buoy, the amplitude and phase of the buoy's motion deviate from the motion on the water surface.

[0005] Specifically, at the crest of a wave, the buoy is subjected to downward wave acceleration. Due to inertia, the downward acceleration of the buoy lags behind the water surface, causing the buoy to rise relative to the water surface, reducing its draft. The GNSS antenna position is higher than the actual water surface position at the corresponding moment. At the trough of a wave, the buoy is subjected to upward wave acceleration. Due to inertia, the buoy sinks relative to the water surface, increasing its draft. The antenna position is lower than the actual water surface position. This dynamic draft offset increases with the increase of wave height and wave frequency.

[0006] Currently, scholars both domestically and internationally have used GNSS buoys for wave observation and compared and verified them with standard wave meters. Studies have already conducted GNSS buoy wave observation experiments in the South China Sea and East China Sea. The results show that in sea conditions with a significant wave height exceeding 2m, there is a 5% to 15% deviation between the wave height measurement value of the GNSS buoy and the measurement value of the pressure wave meter or acoustic Doppler wave meter. In traditional analysis, this deviation is usually attributed to GNSS positioning error or the influence of the buoy mooring. However, the physical mechanism of dynamic draft change caused by the inertial motion of the buoy itself has not been fully understood and utilized.

[0007] Existing GNSS buoy wave inversion technology has the following drawbacks:

[0008] Disadvantage 1: Existing methods assume that the buoy perfectly tracks the water surface movement, ignoring the dynamic draft changes caused by the buoy's mass and inertia. The buoy's draft decreases at wave crests and increases at wave troughs, resulting in a systematic deviation between the GNSS antenna position and the actual water surface that varies with the wave phase.

[0009] Disadvantage 2: Existing methods lack a vertical dynamic model for the buoy, and cannot quantitatively describe the influence of physical parameters such as buoy mass, waterline surface area, and fluid damping on the buoy's motion response. Therefore, it is impossible to correct this bias at the level of physical mechanisms.

[0010] Disadvantage 3: The existing method does not establish a buoy response amplitude operator, and cannot reveal the gain and phase shift characteristics of the buoy tracking the water surface under different frequency waves. The tracking deviation of the high frequency wave component is greater than that of the low frequency component, but the existing method treats all frequency components equally, resulting in the distortion of the inverted wave spectrum shape.

[0011] Disadvantage 4: The existing correction strategy does not have the ability to adapt to sea conditions. Under light wave conditions, the dynamic draft offset is small and no strong correction is needed. Under heavy wave conditions, the offset is significant and stronger correction is required. The existing method cannot automatically adjust the correction intensity according to sea conditions, which leads to overcorrection introducing noise under light wave conditions or undercorrection leaving residual bias under heavy wave conditions. Summary of the Invention

[0012] The purpose of this invention is to provide a GNSS wave inversion method that compensates for the dynamic draft offset of a buoy. This addresses the problem in the prior art where GNSS buoys invert sea surface wave parameters by measuring the position of the GNSS antenna mounted on top of the buoy. Existing techniques directly equate the vertical motion of the GNSS antenna with the motion of sea surface waves, without considering the dynamic draft changes caused by the inertia of the buoy as a rigid body moving in the waves. Since the buoy has a certain mass, its draft decreases at wave crests due to inertia, and the antenna position is higher than the actual water surface; conversely, its draft increases at wave troughs due to inertia, and the antenna position is lower than the actual water surface. This dynamic draft offset leads to a systematic deviation between the antenna trajectory measured by GNSS and the actual water surface motion, reducing the accuracy of wave parameter inversion. The technical problem this invention aims to solve is: to establish a vertical dynamic model of the buoy, calculate the dynamic draft offset in real time, and compensate and correct the GNSS measurement results in the time and frequency domains to improve wave inversion accuracy.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] A GNSS wave inversion method for compensating for dynamic draft shift of buoys includes the following steps:

[0015] Includes the following steps:

[0016] S1. In the GNSS high-frequency observation data acquisition and preprocessing stage, a GNSS receiver installed on the top of the buoy is used to acquire the three-dimensional position time series of the buoy antenna. The original GNSS position series is processed by carrier phase differential processing to obtain a high-precision three-dimensional position series. The vertical velocity and vertical acceleration are calculated and low-pass filtered. The vertical position series is then subjected to quality control and interpolation.

[0017] S2. In the vertical dynamics modeling stage of the buoy, the dynamic equation of the buoy's heave motion in the waves is established, and the buoy's added mass, total damping coefficient, heave natural circular frequency and natural period are calculated.

[0018] S3. Dynamic draft offset characteristic analysis stage: calculate the static draft depth of the buoy, derive the calculation formula for dynamic draft offset, impose boundary constraints on the dynamic draft offset, and calculate the statistical characteristics of the dynamic draft offset.

[0019] S4. Frequency domain response amplitude operator correction stage: Derive the response amplitude operator of the buoy heave motion, use the response amplitude operator to perform frequency domain correction on the buoy motion spectrum measured by GNSS, set the minimum gain threshold to avoid numerical instability, determine the upper limit of the effective correction frequency range, and obtain the corrected vertical displacement time series through inverse Fourier transform after phase correction.

[0020] S5. Wave condition adaptive correction stage: Define the sea condition severity index, determine the adaptive correction weight based on the sea condition severity index, and calculate the final corrected wave spectrum.

[0021] S6. Wave parameter inversion and quality assessment stage: Based on the final corrected wave spectrum, calculate various wave parameters, define data quality scores, and quantify the impact of dynamic draft correction and data reliability.

[0022] As a further improvement to this technical solution: the sampling rate of the GNSS receiver ranges from 1 to 10 Hz; the vertical velocity and vertical acceleration are calculated using the center difference method, and the cutoff frequency of the low-pass filter is set to 0.5 times the sampling rate; the quality control involves removing outliers whose position jumps exceed 3 times the standard deviation, and filling the removed data points with cubic spline interpolation.

[0023] As a further improvement to this technical solution: the buoy is considered as a cylindrical floating body, and its vertical motion satisfies a second-order ordinary differential equation:

[0024]

[0025] in, The mass of the buoy is expressed in kg. Additional mass, unit: kg; The vertical displacement of the buoy relative to its static equilibrium position, in meters (m). Total damping coefficient, in N. s / m; For the density of seawater, take 1025 kg / m³. ; Let gravitational acceleration be 9.81 m / s². ; The waterline area of ​​the buoy, in units of ; Wave excitation force, in N;

[0026] The additional mass is calculated using a hemispherical approximation:

[0027]

[0028] in The diameter of the buoy's waterline is given; the total damping coefficient consists of radiation damping and viscous damping.

[0029] The natural circular frequency of the buoy's heave is:

[0030]

[0031] The inherent period is .

[0032] As a further improvement to this technical solution: the static draft is determined by static equilibrium conditions.

[0033]

[0034] The formula for calculating the dynamic draft offset is:

[0035]

[0036] in, The vertical acceleration of the buoy, in m / s². Upward is positive; the boundary constraint is when At that time, limit its amplitude to ;when At that time, limit its amplitude to The statistical characteristics include standard deviation, extreme values, and the percentage of epochs with limited range.

[0037] As a further improvement to this technical solution: the amplitude and phase of the buoy heave response amplitude operator are respectively:

[0038]

[0039] in, The natural circular frequency of the buoy's heave. The angular frequency of the wave. The damping ratio is dimensionless; the actual wave spectrum is:

[0040]

[0041] The minimum gain threshold is set to 0.1; the upper limit of the effective correction frequency range is:

[0042] .

[0043] As a further improvement to this technical solution: the calculation formula for the sea state severity index is as follows:

[0044]

[0045] in, The initial estimate of the uncorrected effective wave height, in meters; The period of the spectral peak, in seconds. when hour, ;when hour, ;when hour, The final corrected wave spectrum is as follows:

[0046] .

[0047] As a further improvement to this technical solution: the wave parameters include effective wave height, average zero-crossing period, and spectral peak period; the effective wave height is calculated from the spectral zero-order moment.

[0048]

[0049] The average zero-crossing period is calculated from the spectral zero-order moment and the second-order moment:

[0050]

[0051] The spectral peak period is the period corresponding to the maximum spectral density value. The lower limit frequency of the spectral integral is set to 0.03 Hz, and the upper limit frequency is set to... hertz.

[0052] As a further improvement to this technical solution: the calculation formula for the data quality score is as follows:

[0053]

[0054] in, ; for The percentage of eras whose amplitude was limited; This represents the percentage of data points that were removed and interpolated in step S1. , , These are weighting coefficients, taken as 0.4, 0.3, and 0.3 respectively; when At m time, Set it directly to 1.0; Marked as high-quality data Marked as available data. Marked as low-quality data.

[0055] Compared with the prior art, the beneficial effects of the present invention are:

[0056] 1. This invention establishes a buoy vertical inertia-buoyancy-damping dynamic model, which for the first time quantitatively describes the relationship between the dynamic draft offset of the buoy and wave motion from the physical mechanism level. By calculating the dynamic draft offset epoch by epoch and compensating it into the GNSS measurement results, the systematic deviation caused by the buoy inertia effect is eliminated, and the inversion error of the effective wave height is reduced from 8%~15% before correction to less than 3%.

[0057] 2. This invention derives the analytical expression of the buoy heave response amplitude operator, reveals the tracking gain and phase shift characteristics of the buoy for waves of different frequencies, and recovers the high-frequency wave energy by using RAO to correct the wave spectrum in the frequency domain, thereby improving the inversion accuracy of the average period Tz by about 20% and improving the quality of wave spectrum shape restoration.

[0058] 3. This invention designs an adaptive correction strategy based on sea state severity index, which can automatically adjust the correction intensity according to real-time sea state, automatically turn off correction under light wave conditions to avoid introducing noise, and automatically enhance correction to eliminate deviation under heavy wave conditions, thus achieving stable and reliable correction across the entire sea state range.

[0059] 4. The data quality scoring method proposed in this invention can quantify the credibility of each wave data segment, providing a data quality reference for downstream applications. The quality scoring comprehensively considers the correction range, the amplitude limit ratio, and the data missing ratio, enabling data users to select high-quality data in a targeted manner.

[0060] 5. The physical parameters of the buoy required by this invention are all measurable and known quantities. The calculation process is simple and can be run in real time on the embedded processor at the buoy end. No additional sensor hardware is required, which has good engineering feasibility and economy.

[0061] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings. Specific embodiments of the present invention are given in detail below with reference to the accompanying drawings. Attached Figure Description

[0062] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0063] Figure 1 The amplitude and phase characteristics of the buoy heave response amplitude operator of this invention;

[0064] Figure 2 This invention relates to wave time series comparison and dynamic draft offset;

[0065] Figure 3 For comparison of the wave spectrum correction effect of the present invention;

[0066] Figure 4 This invention provides a comparison of wave height inversion errors under different sea states.

[0067] Figure 5 This is a flowchart illustrating the technical route of the present invention. Detailed Implementation

[0068] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. The invention is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0069] Please see Figures 1 to 5 In this embodiment of the invention, a GNSS wave inversion method for compensating for dynamic draft shift of a buoy includes the following steps:

[0070] Step S1: GNSS high-frequency observation data acquisition and preprocessing:

[0071] A GNSS receiver mounted on top of the buoy is used, with a sampling rate of Collect the three-dimensional position time series of the buoy antenna. The value range is 1. At 10Hz, carrier phase differential processing is performed on the original GNSS position sequence to obtain a high-precision three-dimensional position sequence. ,in, , , These are the eastward, northward, and vertical positional components, respectively. The observation time.

[0072] For vertical position sequence Perform numerical differentiation to obtain the vertical velocity. and vertical acceleration :

[0073]

[0074]

[0075] in, The sampling interval is used to perform a low-pass filter on the differential result, with the cutoff frequency set to [value]. This eliminates high-frequency noise in numerical differential amplification.

[0076] Quality control of vertical position sequences: Remove sequences with position jumps exceeding a threshold. Anomalies, Take 3 times the standard deviation; fill in the removed data points using cubic spline interpolation.

[0077] Step S2: Buoy Vertical Dynamics Modeling:

[0078] Establish the dynamic equations for the heave motion of a buoy in waves. Consider the buoy as a cylindrical floating body, and its vertical motion satisfies the following second-order ordinary differential equations:

[0079]

[0080] in, The mass of the buoy is expressed in kg. Additional mass, unit: kg; The vertical displacement of the buoy relative to its static equilibrium position, in meters (m). Total damping coefficient, in N. s / m; For the density of seawater, take 1025 kg / m³. ; Let gravitational acceleration be 9.81 m / s². ; The waterline area of ​​the buoy, in units of ; The wave excitation force is expressed in nanometers (N).

[0081] For a cylindrical buoy, the waterline area , The diameter of the buoy's waterline is in meters (m).

[0082] Added mass Using the hemispherical approximation for calculation:

[0083]

[0084] Total damping coefficient Radiation damping and viscous damping It consists of two parts:

[0085]

[0086] Radiation Damping Related to wave frequency, at the buoy's natural frequency Take the maximum value nearby, viscous damping Expressed using the linearized equivalent damping coefficient:

[0087]

[0088] in, This is the drag coefficient, with a value ranging from 0.5. 1.5, for cylindrical buoys take 1.0; The vertical projected area of ​​the buoy, in units of ; The amplitude of the buoy's heave motion is expressed in meters (m).

[0089] The natural circular frequency of the buoy's heave is:

[0090]

[0091] The inherent period is .

[0092] Step S3: Dynamic draft offset feature analysis:

[0093] Define the dynamic draft offset of the buoy For the buoy in The difference between the static draft and the actual draft at any given time; a positive value indicates a decrease in draft, meaning the buoy rises. The static draft of the buoy... Determined by static equilibrium conditions:

[0094]

[0095] Vertical position measured by GNSS antenna Relative to actual water level The relationship between them is:

[0096]

[0097] in, The antenna installation height is the vertical distance from the antenna phase center to the static draft of the buoy, expressed in meters (m).

[0098] Dynamic draft offset The physical essence of this is the buoyancy imbalance caused by the inertial force of the buoy. According to the vertical force balance of the buoy, when the buoy is subjected to upward acceleration, the inertial force is downward, causing the buoy to sink deeper and increase its draft; conversely, when the buoy is subjected to downward acceleration, the draft decreases. Therefore:

[0099]

[0100] in, The vertical acceleration of the buoy, in m / s². Upward is positive, and this acceleration is directly calculated from step S1. To obtain the buoy's downward acceleration at the wave crest,... , This means the draft decreases, the buoy antenna is positioned above the actual water surface, and at the trough of the wave, the buoy accelerates upwards. , This means that the draft increases, and the buoy antenna is positioned below the actual water surface.

[0101] right Apply boundary constraints: when At that time, limit its amplitude to ;when At that time, limit its amplitude to .

[0102] calculate Statistical characteristics: standard deviation ,extremum and Limitation of historical yuan These statistics are used to determine the adaptive correction parameters in step S5 and to assess the data quality in step S6.

[0103] This step does not correct the wave data. The actual correction is performed in the frequency domain in step S4 to avoid dual correction in the time and frequency domains.

[0104] Step S4: Frequency domain response amplitude operator correction:

[0105] Perform a Fourier transform on the motion equations in step S2 to derive the response amplitude operator (RAO) for the buoy's heave motion, assuming the wave excitation is a single-frequency simple harmonic wave. The buoy heave response is ,in The angular frequency of the wave is expressed in rad / s.

[0106] The buoy heave amplitude (RAO) is defined as the ratio of the buoy's motion amplitude to the wave amplitude.

[0107]

[0108] in, The damping ratio is dimensionless. .

[0109] The amplitude and phase of the RAO are as follows:

[0110]

[0111] when hour, The buoy can track low-frequency waves, when hour, The buoy cannot track high-frequency waves when hour, The buoy exhibits an amplification effect at the resonant frequency.

[0112] Frequency domain correction of the buoy motion spectrum measured by GNSS was performed using RAO. Let the power spectral density of the buoy's vertical displacement measured by GNSS be... True wave spectrum for:

[0113]

[0114] in, Frequency, in Hz.

[0115] To avoid at high frequency ends Numerical instability occurs when the gain approaches zero; a minimum gain threshold is set. The value is 0.1. At that time, Cut off as The upper limit of the effective correction frequency range Determined by the following formula:

[0116]

[0117] Simultaneously, phase correction is performed to eliminate waveform distortion caused by buoy response hysteresis, resulting in the corrected vertical displacement time series. It is obtained by performing an inverse Fourier transform on the corrected spectrum.

[0118] Step S5: Adaptive Wave Condition Correction

[0119] Define sea state severity index Used to automatically determine the impact of dynamic draft drift under current sea state:

[0120]

[0121] in, The initial estimate of the uncorrected effective wave height, in meters; The period of the spectral peak, in seconds. This reflects the steepness of the waves. The larger the value, the steeper the wave and the more significant the buoy's inertial effect.

[0122] according to Value determines adaptive correction weights :

[0123] when hour, No correction is performed; when hour, Full strength correction is used; when hour, Linear transition between 0 and 1:

[0124]

[0125] in, and These are the lower and upper thresholds of the transition interval. Take 0.002, Take 0.006,

[0126] The final corrected wave spectrum is as follows:

[0127]

[0128] when When, output the uncorrected original spectrum; when When, output the fully corrected wave spectrum; when When the time comes, output the weighted fusion result of the two.

[0129] Step S6: Wave parameter inversion and quality assessment:

[0130] Based on the corrected wave spectrum Calculate wave parameters and effective wave height. From the zeroth moment of the spectrum calculate:

[0131]

[0132] in, The lower limit frequency for integration is set to 0.03Hz. Let the upper limit frequency of integration be taken as... Hz.

[0133] Average zero-crossing cycle Calculated from the zeroth and second moments of the spectrum:

[0134]

[0135] in, It is the second moment of the spectrum.

[0136] Spectral peak period The period corresponding to the maximum spectral density: , .

[0137] Define data quality score Quantifying the impact of dynamic draft correction and data reliability:

[0138]

[0139] in, The relative amplitude is corrected for wave height; for The percentage of eras whose amplitude was limited; This represents the percentage of data points that were removed and interpolated in step S1. , , , where are weighting coefficients, taken as 0.4, 0.3, and 0.3 respectively. At m, the effect of dynamic draft offset is negligible. Set it directly to 1.0. The range of values ​​is 0. 1, Marked as high-quality data Marked as available data. Marked as low-quality data.

[0140] To verify the effectiveness of the method proposed in this invention, the following experiment was designed:

[0141] Experimental conditions: A cylindrical GNSS wave observation buoy was used, with a mass of... kg, waterline diameter m, antenna installation height m, GNSS sampling rate Hz, observation duration 600s, damping ratio drag coefficient The static draft of the buoy was calculated. m, natural frequency Hz, inherent period s.

[0142] Experiment 1: Characteristics of the buoy heave response amplitude operator:

[0143] Figure 1 This demonstrates the amplitude and phase variation characteristics of the buoy's heave RAO with frequency, particularly in the low-frequency range ( At its natural frequency (Hz), the RAO amplitude is close to 1.0, allowing the buoy to track surface movements well. As the frequency increases, the RAO amplitude initially decreases at its natural frequency. Resonant amplification occurs near Hz, followed by rapid decay in the high-frequency range, with the phase shifting at the natural frequency. The jump in the value indicates that existing uncorrected methods have significant tracking errors in high-frequency wave components.

[0144] Experiment 2: Correction effect under typical sea conditions:

[0145] Selecting significant wave height m, spectral peak period The sea state of s was verified. Figure 2 The upper part shows a time series comparison of the actual water surface, the uncorrected buoy motion, and the corrected wave sequence. The uncorrected buoy motion is higher at wave crests and lower at wave troughs, while the corrected wave sequence matches the actual water surface well. Figure 2 The lower half shows the dynamic draft offset. The time series has an amplitude of The value is on the order of cm and is inversely correlated with the wave phase.

[0146] The uncorrected significant wave height was 3.731m with a relative error of 6.6%; the corrected significant wave height was 3.512m with the relative error reduced to 0.3%.

[0147] Experiment 3: Wave spectrum correction effect:

[0148] Figure 3 The comparison between the real wave spectrum, the uncorrected buoy motion spectrum, and the RAO-corrected wave spectrum is shown. The uncorrected buoy motion spectrum shows energy amplification near the spectral peak and low energy in the high-frequency band. The RAO-corrected wave spectrum matches the real wave spectrum well in all frequency bands, and the spectral shape is effectively restored.

[0149] Experiment 4: Comparison of multi-sea-state correction performance:

[0150] Figure 4 The comparison of the relative errors of uncorrected and corrected wave height inversion under six different sea states is shown. The uncorrected error increases with decreasing wave period and increasing wave steepness, from 3.3% ( m, s) increased to 13.5% ( m, (s), after correction, the error decreases to within 2% in most sea states, Under small wave conditions, the error after correction is 8.8% due to the influence of GNSS measurement noise.

[0151] Experimental conclusion: In Under sea state m, the method of this invention reduces the relative error of wave height inversion from 3.3%. The percentage decreased from 9.1% to 0.1%. 1.7%.

[0152] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Those skilled in the art can readily implement the present invention based on the description and drawings above. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention using the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A GNSS wave inversion method for compensating for dynamic draft drift of a buoy, characterized in that, Includes the following steps: S1. In the GNSS high-frequency observation data acquisition and preprocessing stage, a GNSS receiver installed on the top of the buoy is used to acquire the three-dimensional position time series of the buoy antenna. The original GNSS position series is processed by carrier phase differential processing to obtain a high-precision three-dimensional position series. The vertical velocity and vertical acceleration are calculated and low-pass filtered. The vertical position series is then subjected to quality control and interpolation. S2. In the vertical dynamics modeling stage of the buoy, the dynamic equation of the buoy's heave motion in the waves is established, and the buoy's added mass, total damping coefficient, heave natural circular frequency and natural period are calculated. S3. Dynamic draft offset characteristic analysis stage: calculate the static draft depth of the buoy, derive the calculation formula for dynamic draft offset, impose boundary constraints on the dynamic draft offset, and calculate the statistical characteristics of the dynamic draft offset. S4. Frequency domain response amplitude operator correction stage: Derive the response amplitude operator of the buoy heave motion, use the response amplitude operator to perform frequency domain correction on the buoy motion spectrum measured by GNSS, set the minimum gain threshold to avoid numerical instability, determine the upper limit of the effective correction frequency range, and obtain the corrected vertical displacement time series through inverse Fourier transform after phase correction. S5. Wave condition adaptive correction stage: Define the sea condition severity index, determine the adaptive correction weight based on the sea condition severity index, and calculate the final corrected wave spectrum. S6. Wave parameter inversion and quality assessment stage: Based on the final corrected wave spectrum, calculate various wave parameters, define data quality scores, and quantify the impact of dynamic draft correction and data reliability.

2. The GNSS wave inversion method for compensating for dynamic draft drift of a buoy according to claim 1, characterized in that, The sampling rate of the GNSS receiver ranges from 1 to 10 Hz; the vertical velocity and vertical acceleration are calculated using the center difference method, and the cutoff frequency of the low-pass filter is set to 0.5 times the sampling rate; the quality control involves removing outliers whose position jumps exceed 3 times the standard deviation, and filling the removed data points with cubic spline interpolation.

3. The GNSS wave inversion method for compensating for dynamic draft drift of a buoy according to claim 1, characterized in that, The buoy is considered a cylindrical floating body, and its vertical motion satisfies a second-order ordinary differential equation: in, The mass of the buoy is expressed in kg. Additional mass, unit: kg; The vertical displacement of the buoy relative to its static equilibrium position, in meters (m). Total damping coefficient, in N. s / m; For the density of seawater, take 1025 kg / m³. ; Let gravitational acceleration be 9.81 m / s². ; The waterline area of ​​the buoy, in units of ; Wave excitation force, in N; The additional mass is calculated using a hemispherical approximation: in The diameter of the buoy's waterline is given; the total damping coefficient consists of radiation damping and viscous damping. The natural circular frequency of the buoy's heave is: The inherent period is .

4. The GNSS wave inversion method for compensating for dynamic draft drift of a buoy according to claim 1, characterized in that, The static draft is determined by static equilibrium conditions: The formula for calculating the dynamic draft offset is: in, The vertical acceleration of the buoy, in m / s². Upward is positive; the boundary constraint is when At that time, limit its amplitude to ;when At that time, limit its amplitude to The statistical characteristics include standard deviation, extreme values, and the percentage of epochs with limited range.

5. The GNSS wave inversion method for compensating for dynamic draft drift of a buoy according to claim 1, characterized in that, The amplitude and phase of the buoy heave response amplitude operator are as follows: in, The natural circular frequency of the buoy's heave. The angular frequency of the wave. The damping ratio is dimensionless; the actual wave spectrum is: The minimum gain threshold is set to 0.1; the upper limit of the effective correction frequency range is: 。 6. The GNSS wave inversion method for compensating for dynamic draft drift of a buoy according to claim 1, characterized in that, The formula for calculating the sea state severity index is as follows: in, The initial estimate of the uncorrected effective wave height, in meters; The period of the spectral peak, in seconds. when hour, ;when hour, ;when hour, The final corrected wave spectrum is as follows: 。 7. The GNSS wave inversion method for compensating for dynamic draft drift of a buoy according to claim 1, characterized in that, The wave parameters include significant wave height, average zero-crossing period, and spectral peak period; the significant wave height is calculated from the spectral zero-order moment. The average zero-crossing period is calculated from the spectral zero-order moment and the second-order moment: The spectral peak period is the period corresponding to the maximum spectral density value. The lower limit frequency of the spectral integral is set to 0.03 Hz, and the upper limit frequency is set to... hertz.

8. The GNSS wave inversion method for compensating for dynamic draft drift of a buoy according to claim 1, characterized in that, The formula for calculating the data quality score is as follows: in, ; for The percentage of eras whose amplitude was limited; This represents the percentage of data points that were removed and interpolated in step S1. , , These are weighting coefficients, taken as 0.4, 0.3, and 0.3 respectively; when At m time, Set it directly to 1.0; Marked as high-quality data Marked as available data. Marked as low-quality data.

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