Method for acquiring ocean surface wave and wind-generated flow parameters in high-wind-speed environment

Abstract

The invention discloses a method for acquiring ocean surface wave and wind-generated flow parameters in a high-wind-speed environment, which comprises the following steps of: constructing a wave spectrum model, and inputting wind speed information into the wave spectrum model to obtain a one-dimensional function of wave, namely a one-dimensional height spectrum of the wave; constructing a direction function model, and inputting the wind speed information and the wind direction information into the direction function model to obtain a wave two-dimensional direction spectrum; and constructing a Doppler spectrum model, and inputting the wave one-dimensional height spectrum and the wave two-dimensional direction spectrum into the Doppler spectrum model to obtain wind-generated flow velocity information caused by wind waves in a high-wind-speed environment. The application value in the high-wind-speed environment is particularly remarkable, a brand new solution is provided for kinetic research of extreme ocean phenomena such as typhoon, and an important scientific basis is provided for ocean resource development and weather forecast.

Description

Technical Field

[0001] The present invention belongs to the field of fully automated products and relates to a method for obtaining parameters of ocean surface waves and wind-induced currents in a high wind speed environment. Background Art

[0002] With the rapid development of remote sensing technology, modern sensors are now able to capture information on wind, waves, and currents on the ocean surface, providing valuable data support for ocean dynamics research. However, existing technologies still have many limitations in accurately and synchronously acquiring and inverting these oceanographic elements. Wind information is relatively simple to obtain, often directly measured by remote sensing sensors, and the data provides comprehensive spatial and temporal coverage. However, acquiring information on waves and currents is much more complex. Direct observation methods are limited by equipment, cost, and technical requirements, and cannot meet the requirements of high accuracy, large coverage, and high spatial and temporal resolution. For example, in-situ wave observations primarily rely on buoys and shipborne equipment. However, buoy deployment and maintenance are costly, the number of buoys is limited, and coverage is insufficient. Shipborne observations, however, are limited by range and operating time, and can only provide localized, short-term data. While remote sensing technology offers advantages in spatial coverage, its resolution is limited, making it difficult to accurately capture short-term wave variations. Furthermore, observing currents is even more challenging, as the results are often the product of multiple factors, including wind-induced current disturbances and the influence of long-term stable factors such as tidal currents and geostrophic currents. The combined effect of these factors makes the analysis and inversion of flow field observation results complex and uncertain.

[0003] In order to make up for the shortcomings of direct observation data, data assimilation and reanalysis techniques are currently commonly used to integrate observation data from different sources into a unified time and space grid, so as to obtain consistent wind, wave and current information at the same resolution. However, this method also brings some technical challenges, including the heterogeneity of data sources, uncertainty in model parameterization, and special needs under high wind speed conditions. Under high wind speed environments, the generation and growth rate of waves is significantly accelerated, the intensity of wind-driven currents is greatly enhanced, and the coupling effect between wind, waves and currents is more significant. Under such conditions, it is more difficult to obtain accurate and synchronized wind, wave and current information through direct observation, and the temporal and spatial resolution and accuracy of existing methods are difficult to meet actual needs. Therefore, starting from high-precision wind field data, deducing the generation and evolution laws of waves and wind-driven currents is not only an important way to improve the level of ocean dynamics research, but also a key method to achieve accurate inversion of wind, wave and current coupling fields under high wind speed conditions. Summary of the Invention

[0004] In order to solve the above problems, the technical solution adopted by the present invention is: a method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment, comprising the following steps:

[0005] Construct a wave spectrum model, input wind speed information into the wave spectrum model to obtain a one-dimensional function of the wave, that is, a one-dimensional wave height spectrum;

[0006] Construct a directional function model, input wind speed and direction information into the directional function model to obtain a two-dimensional wave directional spectrum;

[0007] A Doppler spectrum model is constructed, and the one-dimensional wave height spectrum and the two-dimensional wave direction spectrum are input into the Doppler spectrum model to obtain the wind-induced flow velocity information caused by wind waves in a high wind speed environment.

[0008] Furthermore: the wave spectrum model adopts Apel spectrum.

[0009] Furthermore, the expression of the wave spectrum model Ψ(k) is as follows:

[0010] Ψ(k)=A·L0·J p ·k -4 ·H i (1)

[0011] Where k is the wave number, A is a constant, L0 is the low wave number roll-off model, J p Describes the nonlinear peak effect of the Joint North Sea Wave Project Spectral (JONSWAP), H i Represents the net spectrum in the gravity-capillary wave peak region.

[0012] Furthermore, the directional function model adopts a Gaussian directional function, that is, a directional function that conforms to a Gaussian form.

[0013] Furthermore: the direction function model The expression is as follows:

[0014]

[0015] Where c1 is 400rad / s, u n 、k n It is a quantity introduced to remove the dimension. Its value is 1. Its unit is consistent with the unit of wind speed and wave number. 10 is the wind speed at 10 meters above sea level, k is the wave number is the wind direction, and σ is the width parameter.

[0016] Furthermore, the Doppler spectrum model is used to study the Doppler frequency shift of the sea surface backscattering in the radar Ka band.

[0017] Furthermore, the Doppler shift includes the Doppler shift caused by the Bragg wave phase velocity and the Doppler shift caused by the long-wave orbital motion.

[0018] Furthermore: the Doppler frequency shift f D The expression is as follows:

[0019]

[0020] Where f D represents the Doppler shift, k b is the wave number corresponding to the Bragg wave that resonates with the incident electromagnetic wave, k0 is a constant of 363 rad / m, D * (k) is the complex conjugate of the complex Doppler modulation transfer function, Modulation transfer function representing the backscatter coefficient of the sea surface.

[0021] Further: calculate the wind-induced flow field information, that is:

[0022]

[0023] Where V is the Doppler velocity, that is, the velocity of the wind-driven flow, and λ is the radar operating wavelength.

[0024] Furthermore: the high wind speed is >9m / s.

[0025] A device for acquiring ocean surface wave and wind-induced current parameters in a high wind speed environment, comprising:

[0026] Constructing a wave spectrum model module: used to construct a wave spectrum model, input wind speed information into the wave spectrum model to obtain a one-dimensional function of the wave, that is, a one-dimensional wave height spectrum;

[0027] Constructing a directional function model module: used to input wind speed information and wind direction information into the directional function model to obtain a two-dimensional wave directional spectrum;

[0028] A Doppler spectrum model is constructed to input the one-dimensional wave height spectrum and the two-dimensional wave direction spectrum into the Doppler spectrum model to obtain the wind-induced flow velocity information caused by wind waves.

[0029] The present invention provides a method for acquiring ocean surface wave and wind-driven current parameters in high-wind-speed environments. This method uses high-precision wind field data to deduce wave generation and wind-driven current intensity variations, thereby enabling precise and simultaneous acquisition of wave and wind-driven current parameters. By combining a nonlinear wave dynamics model, namely the Apel spectrum, with a wave directional function model, namely the Gaussian directional function, the present invention establishes a wind-wave-current coupled computational framework suitable for high-wind-speed conditions. This framework incorporates the Doppler shift caused by the Bragg wave phase velocity and the Doppler shift caused by the long-wave orbital motion, thereby enabling acquisition of wave parameters and wind-driven current field information under known wind conditions. This method not only overcomes the limitations of traditional observation methods in high-wind-speed environments but also significantly improves the accuracy of wave and wind-driven current inversion, providing powerful technical support for marine environmental monitoring, disaster warning, and prevention in extreme weather conditions. The present invention is particularly valuable in high-wind-speed environments, offering a novel solution for the dynamics research of extreme ocean phenomena such as typhoons and providing an important scientific basis for marine resource development and weather forecasting.

[0030] The present invention proposes a method for obtaining ocean surface waves and wind-induced current parameters under high wind speed environment. The method establishes a Doppler spectrum model. The wave spectrum model and the directional function model are used to not only quantitatively analyze the wind and waves and obtain the wave parameters under the wind speed, but also to achieve relatively accurate fitting of the wind-induced flow field under high wind speed conditions, laying the foundation for subsequent accurate inversion of the flow field.

[0031] This method (1) can obtain information on waves and wind-driven currents simply by measuring the wind field; (2) the flow field data obtained under high wind speeds (above 9 m / s) can well fit the actual observation values; (3) the simulation process is simple; (4) it can effectively overcome the limitations of traditional observation methods in high wind speed environments and significantly improve the accuracy and efficiency of ocean dynamics research, weather forecasting, and marine resource development. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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 or the description of the prior art. Obviously, the drawings described below are 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 labor.

[0033] Figure 1 It is a flow chart of wind-induced flow field simulation;

[0034] Figure 2 is the relationship between wave height spectrum and wave number k;

[0035] Figure 3 is the polar plot of the direction function. DETAILED DESCRIPTION

[0036] It should be noted that, unless there is any conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0038] Estimating the Doppler shift caused by wind and waves requires the input of the wave direction spectrum. The wave direction spectrum is a representation of the sea surface flow state. Different wave spectra represent different sea surface states and have different focuses, which will lead to the inability to accurately estimate the contribution of wind and waves to the Doppler shift, thereby affecting the inversion of the sea surface flow field. Therefore, it is very important to choose an appropriate wave direction distribution function and wave spectrum model.

[0039] Figure 1 It is a flow chart of wind-induced flow field simulation;

[0040] A method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment comprises the following steps:

[0041] S1: Construct a wave spectrum model, input wind speed information into the wave spectrum model to obtain a one-dimensional function of the wave, that is, a one-dimensional wave height spectrum;

[0042] S2: constructing a directional function model, inputting wind speed information and wind direction information into the directional function model to obtain a two-dimensional wave directional spectrum;

[0043] S3: Construct a Doppler spectrum model, input the one-dimensional wave height spectrum and the two-dimensional wave direction spectrum into the Doppler spectrum model, and obtain the wind-induced flow velocity information caused by wind waves.

[0044] Steps S1 / S2 / S3 are performed sequentially;

[0045] The process of establishing the wave spectrum model is as follows:

[0046] The wave spectrum is an important tool for describing the energy distribution of waves in terms of frequency and direction. It uses a mathematical model to characterize how wave energy is distributed in different frequencies and directions, and can be used for wave prediction. The wave spectrum can be divided into a single-parameter spectrum, a two-parameter spectrum, and a two-dimensional wave spectrum that takes directional distribution into account. Common ones include the Pierson-Moskowitz (PM) spectrum, the JONSWAP spectrum, the Bretschneider (BS) spectrum, and the Apel spectrum used in the present invention. These spectra all have their own applicability. The PM spectrum is suitable for describing deep-water wind and waves, and the JONSWAP spectrum is suitable for limited development wind and waves. Since it is modeled using the North Sea Joint Wave Observation Project dataset, it is more suitable for modeling waves in the North Sea. The BS spectrum is mainly used to describe the frequency distribution of offshore waves, and the Apel spectrum used in the present invention is suitable for wave spectrum modeling under high wind speed conditions.

[0047] By building the Apel spectrum wave spectrum model, we can obtain wave information through the wind field. The wave spectrum height model Ψ(k) is as follows:

[0048] Ψ(k)=A·L0·J p ·k -4 ·H i (1)

[0049] Where k is the wave number, A is a constant, and different values are used in different studies. In this paper, A=0.00195 is used, J p Describes the nonlinear peak effect of the Joint North Sea Wave Project Spectral (JONSWAP), H i represents the net spectrum in the gravity-capillary wave (GCW) peak region, L0 is the low-wavenumber roll-off model, and is expressed as:

[0050]

[0051] Among them, k p is the spectrum peak, and the specific calculation formula is as shown in the formula:

[0052]

[0053] Among them, g is the universal gravitational constant, which is generally taken as 9.8, u 10 The wind speed at a height of ten meters above sea level can effectively represent the wind field characteristics close to the surface, weakening the influence of surface friction effect. It is referred to as wind speed below.

[0054] JONSWAP nonlinear peak effect J p Expressed as:

[0055]

[0056] Where Γ is a constant and is taken as 1.7, and δ is the width parameter of the spectral peak and is taken as 0.40.

[0057] Net spectrum H in the gravity-capillary wave (GCW) peak region i Expressed as:

[0058] H i =A·[R ro +S·R res ]·V dis (5)

[0059] Where S is the least squares fitting of the saturation exponential form to the spectral peak, R res is the resonance when the wave number k = 750, V dis represents an exponential decay process concentrated near 1 mm, R ro The roll-off formula is used as a high-pass secondary filter to filter, which is expressed as:

[0060]

[0061] Where k ro It is 100rad / m, which is the roll-off frequency.

[0062]

[0063] Where s1 is a constant and takes -4.95, s2 is a constant and takes 3.45, u η is a constant, take 4.7m / s.

[0064]

[0065] Where a is a constant with a value of 0.8, k res is the resonant wave number, which is 400rad / m, which is different from the resonant wave number in numerical value. It is mainly due to the algebraic combination transformation, which reduces its value.

[0066]

[0067] Where k dis Take 6283rad / m.

[0068] The wave height spectrum as a function of wave number k is as follows Figure 2As shown in the figure, the wave height under different wave number k conditions is described. In the figure, the blue, yellow, red, purple and green spectral lines respectively represent the change of wave height spectrum with wave number k when the wind speed is 24m / s, 12m / s, 6m / s, 3m / s and 1.5m / s. By comparing these spectral lines, we can know that under the same wave number, the wave height decreases synchronously with the decrease of wind speed, and the spectral lines separate after the wave number k is greater than 10. The wave height spectrum under low wind speed represented by the green and purple lines has a decreasing trend less as the wave number increases, while the wave height spectrum under high wind speed represented by the blue and red lines has a slow decreasing trend as the wave number increases.

[0069] This wave spectrum is selected because it has an excellent fit with the wave spectrum model obtained by actual observation when combined with the wave direction distribution function selected by the present invention under high wind speed environment, and can simulate waves under high wind speed conditions.

[0070] The process of establishing the direction function model is as follows:

[0071] The directional distribution function is a mathematical expression that describes the distribution of wave energy in different directions. It is an important component of the wave spectrum model. It is a function used to characterize how wave energy spreads from the main wave direction to other directions. It can be used to reflect the directionality of waves. There are mainly cosine types such as Cosine-2s function, Cosine-nth form and Gaussian form. The most basic of the Cosine-nth form is the Cosine-squared directional function, which is asymmetric with respect to the wind and headwind directions, with the peak located in the wind direction. The other cosine-type Cosine-2s directional function is also asymmetric with respect to the downwind and upwind directions. The wave energy is concentrated near the downwind direction and is almost 0 in the upwind direction. The energy distribution of the waves in the downwind direction is closely related to the distribution coefficient s. The larger the distribution coefficient s is, the more concentrated the energy is in the downwind direction. The Gaussian directional function used in the present invention shows sensitivity to wind speed. As the wave number increases, its directionality gradually weakens. It is also asymmetric with respect to the downwind and upwind directions.

[0072] Gaussian direction function It is a method to obtain wave and wind-induced current information based on the wind field, which is expressed as:

[0073]

[0074] Where c1 is 400rad / s, u n 、k n It is a quantity introduced to remove the dimension. Its value is 1 and its unit is standard unit. 10 is the wind speed at 10 meters above sea level, k is the wave number, and the formula is is the wind direction, and σ is the width parameter. This function is symmetrical, and the surface wave direction distribution is symmetrical, which is suitable for describing the case where the main wave direction is single.

[0075] Under different wave number k conditions, such as Figure 3 As shown in the image, blue, red, yellow, purple and green are the images of the direction function on the polar coordinate axis when the wave number k is 0.1, 1, 10, 100 and 1000 respectively. It can be seen that the energy of the wind field is mainly concentrated in the downwind direction, and the wind field propagates more wave energy in the downwind direction.

[0076] The process of establishing the Doppler spectrum model is as follows:

[0077] This paper considers studying the Doppler shift of sea surface backscatter in the radar Ka band. Here, it is necessary to consider the Doppler shift caused by two factors: the extremely short wave component that matches Bragg scattering and the long wave orbital motion of the waves. The specific formula is as follows:

[0078]

[0079] Where f D represents the Doppler shift, k b is the wave number corresponding to the Bragg wave that resonates with the incident electromagnetic wave, k0 is a constant of 363 rad / m, D * (k) is the complex conjugate of the complex Doppler modulation transfer function, represents the modulation transfer function of the sea surface backscatter coefficient. The first term is the Doppler shift due to the Bragg wave phase velocity, and the second term is the Doppler shift due to the long-wave orbital motion. By combining these two terms, we can obtain the Doppler shift caused by wind and waves.

[0080] The relationship between Doppler shift and velocity is as follows:

[0081]

[0082] Where V is the Doppler velocity, which is the velocity of the wind-driven flow here, and λ is the radar operating wavelength, which can be obtained from the frequency:

[0083]

[0084] Where c is the speed of light and f is the radar operating frequency. The velocity of the wind-driven flow can be obtained from the formula.

[0085] Further: calculate the wind-induced flow field information, that is:

[0086]

[0087] Where V is the Doppler velocity, that is, the velocity of the wind-driven flow, and λ is the radar operating wavelength.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment, characterized by: The following steps are involved: Construct a wave spectrum model, input wind speed information into the wave spectrum model to obtain a one-dimensional function of the wave, that is, a one-dimensional wave height spectrum; Construct a directional function model, input wind speed and direction information into the directional function model to obtain a two-dimensional wave directional spectrum; A Doppler spectrum model is constructed, and the one-dimensional wave height spectrum and the two-dimensional wave direction spectrum are input into the Doppler spectrum model to obtain the wind-induced flow velocity information caused by wind waves in a high wind speed environment.

2. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 1, characterized in that: The wave spectrum model adopts Appel spectrum.

3. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 1, characterized in that: The expression of the wave spectrum model Ψ(k) is as follows: Ψ(k)=A·L0·J p ·to -4 ·H i (1) Where k is the wave number, A is a constant, L0 is the low wave number roll-off model, J p Describes the nonlinear peak effect of the Joint North Sea Wave Plan spectrum, H i Represents the net spectrum in the gravity-capillary wave peak region.

4. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 1, characterized in that: The directional function model adopts a Gaussian directional function.

5. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 1, characterized in that: The direction function model The expression is as follows: Where c1 is 400rad / s, u n 、k n It is a quantity introduced to remove the dimension. Its value is 1. Its unit is consistent with the unit of wind speed and wave number. 10 is the wind speed at 10 meters above sea level, k is the wave number, and the formula is is the wind direction, and σ is the width parameter.

6. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 1, characterized in that: The Doppler spectrum model is used to study the Doppler frequency shift of the backscattered sea surface in the radar Ka band.

7. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 6, characterized in that: The Doppler shift includes the Doppler shift caused by the Bragg wave phase velocity and the Doppler shift caused by the long-wave orbital motion.

8. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 6, characterized in that: The Doppler shift f D The expression is as follows: Where f D represents the Doppler shift, k b is the wave number corresponding to the Bragg wave that resonates with the incident electromagnetic wave, k0 is a constant of 363 rad / m, D * (k) is the complex conjugate of the complex Doppler modulation transfer function, Modulation transfer function representing the backscatter coefficient of the sea surface.

9. The method for obtaining ocean surface wave and wind-induced current parameters in a high wind speed environment according to claim 1, characterized in that: The high wind speed is >9m / s.

10. A device for acquiring ocean surface wave and wind-induced current parameters in a high wind speed environment, characterized by: include: Constructing a wave spectrum model module: used to construct a wave spectrum model, input wind speed information into the wave spectrum model to obtain a one-dimensional function of the wave, that is, a one-dimensional wave height spectrum; Constructing a directional function model module: used to input wind speed information and wind direction information into the directional function model to obtain a two-dimensional wave directional spectrum; A Doppler spectrum model is constructed to input the one-dimensional wave height spectrum and the two-dimensional wave direction spectrum into the Doppler spectrum model to obtain the wind-induced flow velocity information caused by wind waves.

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