CN109283495B - X-band radar ocean current inversion method based on cross spectrum analysis - Google Patents

X-band radar ocean current inversion method based on cross spectrum analysis Download PDF

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CN109283495B
CN109283495B CN201811035048.0A CN201811035048A CN109283495B CN 109283495 B CN109283495 B CN 109283495B CN 201811035048 A CN201811035048 A CN 201811035048A CN 109283495 B CN109283495 B CN 109283495B
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何宜军
陈忠彪
张彪
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Nanjing University of Information Science and Technology
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Abstract

The invention provides an X-band radar ocean current inversion method based on cross spectrum analysis, which comprises the steps of firstly, respectively carrying out cross spectrum analysis on two adjacent images in an X-band radar image to obtain a coherence coefficient spectrum and a phase spectrum; then, respectively averaging the coherence coefficient spectrum and the phase spectrum, determining the dominant wave number according to the peak value of the coherence coefficient spectrum, and eliminating the direction ambiguity of the dominant wave direction by using the average phase; and selecting different wave directions, establishing a model according to the phase velocity obtained by the frequency dispersion relation, and solving by using a least square method to obtain the ocean current vector. The method can solve the problems that the X-band radar has low accuracy in observing the sea surface flow field and a set of coherent X-band radar cannot obtain a vector flow field in the prior art, so as to meet the requirements of business observation of offshore marine environment, marine production and life service and the like.

Description

一种基于交叉谱分析的X波段雷达海流反演方法An X-band Radar Current Inversion Method Based on Cross Spectrum Analysis

技术领域technical field

本发明属于海洋遥感技术领域，具体地涉及一种基于交叉谱分析的X波段雷达海流反演方法。The invention belongs to the technical field of ocean remote sensing, and in particular relates to an X-band radar ocean current inversion method based on cross-spectrum analysis.

背景技术Background technique

海面流场是重要的海洋动力学参数，它不仅影响海洋工程、舰船航行、海洋养殖和娱乐等活动，还与近年来日益严重的海洋溢油污染和赤潮等海洋灾害的发生、发展等密切相关，因而海流的观测具有重要意义。海流计和声学多普勒流速剖面仪(ADCP)等被广泛用于海流的观测，但是它们只能获得点或线的海流变化、安装和维护困难、费用高，尤其是在人们关注的复杂海区或者极端海况下可能无法使用。卫星遥感能获得大面积的海流，但是星载雷达高度计只能获得地转流、合成孔径雷达只能测量径向流速，而且其时间和空间分辨率差，卫星的重复访问周期长，因而不能满足近岸业务化的海流观测需求。X波段雷达具有高时间和空间分辨率，能够全天时、全天候观测海面，近年来被广泛应用于海流的观测中。The sea surface flow field is an important marine dynamic parameter. It not only affects marine engineering, ship navigation, marine aquaculture and entertainment, etc., but is also closely related to the occurrence and development of marine disasters such as the increasingly serious marine oil spill pollution and red tide in recent years. Therefore, the observation of ocean currents is of great significance. Current meters and Acoustic Doppler Current Profiler (ADCP) are widely used in ocean current observation, but they can only obtain point or line current changes, difficult to install and maintain, and high cost, especially in complex sea areas that people are concerned about Or it may not be usable in extreme sea conditions. Satellite remote sensing can obtain large-scale ocean currents, but spaceborne radar altimeters can only obtain geostrophic currents, and synthetic aperture radars can only measure radial flow velocity, and their temporal and spatial resolutions are poor, and the repeated access period of satellites is long, so it cannot meet the Nearshore operational ocean current observation needs. X-band radar has high temporal and spatial resolution and can observe the sea surface all day, all weather, and has been widely used in the observation of ocean currents in recent years.

目前主要有船载导航X波段雷达和相参X波段雷达都用于近岸的海流观测。利用非相参的导航X波段雷达图像反演海流的算法主要是基于Young等人(1985)提出的三维傅里叶变换算法[1-4]，但是它需要利用经验的调制传递函数将雷达图像谱转化为海浪谱，而该调制传递函数与雷达系统、海况、安装条件等因素有关，很难准确确定，利用不同的实验数据和仿真方法得到的调制传递函数的形式差别很大[4,5]。相参雷达可以记录海面回波的强度和相位信息，根据多普勒效应可以从回波的相位中获得海面的径向速度，但是该径向流速与海流、波浪运动等相关，不易分离出海流，并且需要两套以上雷达同步观测获得矢量流场[2]。另外，由于雷达系统的限制，两种雷达都存在时间采样混叠、雷达图像随距离和方向衰减等问题，这些因素限制了海流的观测精度。因此，发明一种简单易行的利用X波段雷达反演海面流场的方法，以解决现有技术中相参和非相参X波段雷达观测海流的精度较差、以及仅利用一套相参雷达无法获得矢量流场等问题已成为本技术领域中急待解决的技术问题。At present, there are mainly ship-borne navigation X-band radars and coherent X-band radars that are used for near-shore ocean current observations. The algorithm of using non-coherent navigation X-band radar image to invert ocean current is mainly based on the three-dimensional Fourier transform algorithm proposed by Young et al. The spectrum is converted into the wave spectrum, and the modulation transfer function is related to the radar system, sea conditions, installation conditions and other factors, and it is difficult to accurately determine the modulation transfer function obtained by different experimental data and simulation methods. The form of the transfer function is very different [4,5 ] . The coherent radar can record the intensity and phase information of the sea surface echo, and the radial velocity of the sea surface can be obtained from the phase of the echo according to the Doppler effect, but the radial velocity is related to the ocean current, wave motion, etc. , and need more than two sets of radar synchronous observation to obtain the vector flow field [2] . In addition, due to the limitations of the radar system, both radars have problems such as time sampling aliasing, radar image attenuation with distance and direction, etc. These factors limit the observation accuracy of ocean currents. Therefore, a simple and easy method for using X-band radar to invert the sea surface flow field is invented, so as to solve the problem that the coherent and non-coherent X-band radars in the prior art have poor accuracy in observing sea currents, and only use one set of coherent radars. The problem that the radar cannot obtain the vector flow field has become an urgent technical problem to be solved in this technical field.

参考文献：references:

[1]I.R.Young,W.Rosenthal,and F.Ziemer,"A three-dimensional analysisof marine radar images for the determination of ocean wave directionality andsurface currents,"Journal of Geophysical Research,vol.90,pp.1049-1059,1985.[1] I.R.Young,W.Rosenthal,and F.Ziemer,"A three-dimensional analysisof marine radar images for the determination of ocean wave directionality and surface currents,"Journal of Geophysical Research,vol.90,pp.1049-1059, 1985.

[2]Trizna Dennis,Method and apparatus for coherent marine radarmeasurements of properties of ocean waves and currents，申请号：US20100868912,美国专利，申请日：2010.8.26[2] Trizna Dennis, Method and apparatus for coherent marine radarmeasurements of properties of ocean waves and currents, application number: US20100868912, US patent, application date: 2010.8.26

[3]吴雄斌等，一种X波段测波雷达海流反演预处理方法，申请号：CN201310029849.7，中国，申请日：2013.1.25[3] Wu Xiongbin et al., A preprocessing method for ocean current inversion by X-band wave measuring radar, application number: CN201310029849.7, China, application date: 2013.1.25

[4]J.C.Nieto-Borge,G.R.Rodriguez,K.Hessner,and P.I.Gonzalez,"Inversion of Marine Radar Images for Surface Wave Analysis,"Journal ofAtmospheric and Oceanic Technology,vol.21,pp.1291-1300,2004.[4] J.C.Nieto-Borge, G.R.Rodriguez, K.Hessner, and P.I.Gonzalez, "Inversion of Marine Radar Images for Surface Wave Analysis," Journal of Atmospheric and Oceanic Technology, vol.21, pp.1291-1300, 2004.

[5]Zhongbiao Chen，Biao Zhang，Yijun He，Zhongfeng Qiu，Perrie William，ANew Modulation Transfer Function for Ocean Wave Spectra Retrieval from X-bandMarine Radar Imagery，Chinese Journal of Oceanology and Limnology.Vol.33No.5,P.1132-1141,2015.[5] Zhongbiao Chen, Biao Zhang, Yijun He, Zhongfeng Qiu, Perrie William, ANew Modulation Transfer Function for Ocean Wave Spectra Retrieval from X-band Marine Radar Imagery, Chinese Journal of Oceanology and Limnology.Vol.33No.5,P.1132 -1141, 2015.

发明内容SUMMARY OF THE INVENTION

发明目的：本发明提供一种简单易行的利用X波段雷达图像反演海面流场的方法，以解决现有技术中X波段雷达观测海流的精度较低、以及利用一套相参X波段雷达无法获得矢量流场的问题。Purpose of the invention: The present invention provides a simple and easy method for using X-band radar images to invert the sea surface flow field, so as to solve the problem that the X-band radar in the prior art has low accuracy in observing ocean currents, and the use of a set of coherent X-band radars The problem that the vector flow field cannot be obtained.

技术方案：本发明提供一种基于交叉谱分析的X波段雷达海流反演方法，具体包括如下步骤：Technical solution: The present invention provides an X-band radar ocean current inversion method based on cross-spectrum analysis, which specifically includes the following steps:

步骤1：选取X波段雷达图像序列I，对相邻的两幅图像分别做交叉谱分析，得到相干系数

Figure GDA0003545122210000021
Step 1: Select the X-band radar image sequence I, and perform cross-spectrum analysis on the two adjacent images to obtain the coherence coefficient
Figure GDA0003545122210000021

Figure GDA0003545122210000022
Figure GDA0003545122210000022

和相位

Figure GDA0003545122210000023
and phase
Figure GDA0003545122210000023

Φij(k,φ)＝arg(Sij),i,j＝1,2,…,n (2)Φ ij (k, φ)=arg(S ij ),i,j=1,2,...,n (2)

其中Ii(x，y)是雷达图像的强度值，x和y为图像中点的横坐标和纵坐标，i和j为图像的序列，n为图像的数量，k与

Figure GDA0003545122210000031
组成频域坐标，K为波数，
Figure GDA0003545122210000032
为波向，Sij是图像Ii(x，y)与Ij(x，y)的功率谱，Sii为Ii(x，y)与其自身的功率谱，arg()表示取复数的辐角。where I i (x, y) is the intensity value of the radar image, x and y are the abscissa and ordinate of the point in the image, i and j are the sequence of images, n is the number of images, and k is the same as the
Figure GDA0003545122210000031
Composition frequency domain coordinates, K is the wave number,
Figure GDA0003545122210000032
is the wave direction, S ij is the power spectrum of the images I i (x, y) and I j (x, y), S ii is the power spectrum of I i (x, y) and itself, arg() represents the complex number Argument.

步骤2：根据步骤1的相干系数

Figure GDA0003545122210000033
和相位
Figure GDA0003545122210000034
对所有相邻的图像做交叉谱分析，得到平均相干系数
Figure GDA0003545122210000035
Step 2: According to the coherence coefficient of step 1
Figure GDA0003545122210000033
and phase
Figure GDA0003545122210000034
Perform cross-spectral analysis on all adjacent images to obtain the average coherence coefficient
Figure GDA0003545122210000035

Figure GDA0003545122210000036
Figure GDA0003545122210000036

和平均相位

Figure GDA0003545122210000037
and average phase
Figure GDA0003545122210000037

Figure GDA0003545122210000038
Figure GDA0003545122210000038

步骤3：根据步骤1中的相干系数的峰值确定主波波数km，并利用步骤2中的平均相位确定真实主波波数用于消除180度的方向模糊；所述180度的方向模糊为方程3中平均相干系数的两个关于远点对称的最大值。Step 3: Determine the main wave number km according to the peak value of the coherence coefficient in step 1, and use the average phase in step 2 to determine the true main wave wave number for eliminating the 180-degree directional blur; the 180-degree directional blur is the equation The two maxima of the average coherence coefficient in 3 are symmetrical about the far point.

步骤4：选择主波波向φm附近的不同方向的所有的波向φp，p为波向φm附近的不同方向的所有波向的个数，并建立如下模型；Step 4: Select all wave directions φ p in different directions near the main wave direction φ m , where p is the number of all wave directions in different directions near the wave direction φ m , and establish the following model;

Figure GDA0003545122210000039
Figure GDA0003545122210000039

利用最小二乘法求解方程5，得出海流矢量

Figure GDA00035451222100000310
的值；Solving Equation 5 using the least squares method yields the current vector
Figure GDA00035451222100000310
the value of;

其中，cradar为波向

Figure GDA00035451222100000311
方向波浪的相速度，
Figure GDA00035451222100000312
ctheory为相速度的理论值，根据海浪的频散关系理论，得到
Figure GDA00035451222100000313
其中g为重力加速度；h为水深，
Figure GDA00035451222100000314
为海流矢量，Δt为相邻两幅图像的时间间隔，所有两幅图像之间的时间间隔均相同；
Figure GDA0003545122210000041
为波数矢量；Q＝1，2，3，...，p。Among them, c radar is the wave direction
Figure GDA00035451222100000311
the phase velocity of the directional waves,
Figure GDA00035451222100000312
c theory is the theoretical value of the phase velocity. According to the theory of the dispersion relation of ocean waves, we get
Figure GDA00035451222100000313
where g is the acceleration of gravity; h is the water depth,
Figure GDA00035451222100000314
is the current vector, Δt is the time interval between two adjacent images, and the time interval between all two images is the same;
Figure GDA0003545122210000041
is the wavenumber vector; Q=1, 2, 3, ..., p.

进一步的，所述步骤3中确定真实主波波数用于消除180度的方向模糊，选择真实主波波数的方法为：选择满足

Figure GDA0003545122210000042
的峰值波数
Figure GDA0003545122210000043
为真实的主波波数。Further, the determination of the true main wave number in the step 3 is used to eliminate the 180-degree direction blur, and the method for selecting the true main wave number is:
Figure GDA0003545122210000042
The peak wavenumber of
Figure GDA0003545122210000043
is the real main wave number.

进一步的，所述步骤4中选择的波向φp，该波向φp同时满足下列要求：Further, the wave direction φ p selected in the step 4, the wave direction φ p simultaneously meets the following requirements:

1，φp的相干系数γ(k，φp)＞0.6，其中波数k满足：0.03≤k≤0.3tad/m；1. The coherence coefficient of φ p γ(k, φ p )>0.6, where the wave number k satisfies: 0.03≤k≤0.3tad/m;

2，|φp-φm|＜30°，

Figure GDA0003545122210000044
为主波波向。2, |φ p -φ m |＜30°,
Figure GDA0003545122210000044
Main wave direction.

有益效果：本发明简单易行，能够解决现有技术中X波段雷达观测海面流场精度较低、以及利用一套相参X波段雷达不能获得矢量流场的问题，以满足近岸海洋环境的业务化观测、服务海洋生产和生活等需求。Beneficial effects: the invention is simple and easy to implement, and can solve the problems in the prior art that the X-band radar observes the sea surface flow field with low precision and the vector flow field cannot be obtained by using a set of coherent X-band radar, so as to meet the requirements of the near-shore marine environment. Operational observation, serving the needs of marine production and life.

附图说明Description of drawings

图1为本发明的算法流程图；Fig. 1 is the algorithm flow chart of the present invention;

图2为本发明利用一幅X波段雷达图像获得的海浪相速度与理论相速度的比较。FIG. 2 is a comparison between the wave phase velocity obtained by using an X-band radar image in the present invention and the theoretical phase velocity.

具体实施方式Detailed ways

构成本发明的一部分的附图用来提供对本发明的进一步理解，本发明的示意性实施例及其说明用于解释本发明，并不构成对本发明的不当限定。The accompanying drawings constituting a part of the present invention are used to provide further understanding of the present invention, and the exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention.

如图1所示，本发明提供一种基于交叉谱分析的X波段雷达海流反演方法，具体包括如下步骤：As shown in FIG. 1 , the present invention provides an X-band radar ocean current inversion method based on cross-spectrum analysis, which specifically includes the following steps:

步骤1：选取X波段雷达图像序列I，对相邻的两幅图像分别做交叉谱分析，得到相干系数

Figure GDA0003545122210000045
Step 1: Select the X-band radar image sequence I, and perform cross-spectrum analysis on the two adjacent images to obtain the coherence coefficient
Figure GDA0003545122210000045

Figure GDA0003545122210000046
Figure GDA0003545122210000046

和相位

Figure GDA0003545122210000047
and phase
Figure GDA0003545122210000047

Figure GDA0003545122210000048
Figure GDA0003545122210000048

其中Ii(x，y)是雷达图像的强度值，x和y为图像中点的横坐标和纵坐标，i和j为图像的序列，n为图像的数量，k与

Figure GDA0003545122210000051
组成频域坐标，K为波数，
Figure GDA0003545122210000052
为波向，Sij是图像Ii(x，y)与Ij(x，y)的功率谱，Sii为Ii(x，y)与其自身的功率谱，arg()表示取复数的辐角；where I i (x, y) is the intensity value of the radar image, x and y are the abscissa and ordinate of the point in the image, i and j are the sequence of images, n is the number of images, and k is the same as the
Figure GDA0003545122210000051
Composition frequency domain coordinates, K is the wave number,
Figure GDA0003545122210000052
is the wave direction, S ij is the power spectrum of the images I i (x, y) and I j (x, y), S ii is the power spectrum of I i (x, y) and itself, arg() represents the complex number argument;

步骤2：根据步骤1的相干系数

Figure GDA0003545122210000053
和相位
Figure GDA0003545122210000054
对所有相邻的图像做交叉谱分析，得到平均相干系数
Figure GDA0003545122210000055
Step 2: According to the coherence coefficient of step 1
Figure GDA0003545122210000053
and phase
Figure GDA0003545122210000054
Perform cross-spectral analysis on all adjacent images to obtain the average coherence coefficient
Figure GDA0003545122210000055

Figure GDA0003545122210000056
Figure GDA0003545122210000056

和平均相位

Figure GDA0003545122210000057
and average phase
Figure GDA0003545122210000057

Figure GDA0003545122210000058
Figure GDA0003545122210000058

步骤3：根据步骤1中的相干系数的峰值确定主波波数km，并利用步骤2中的平均相位确定真实主波波数用于消除180度的方向模糊；Step 3: Determine the main wave wave number km according to the peak value of the coherence coefficient in step 1, and use the average phase in step 2 to determine the real main wave wave number for eliminating the 180-degree direction blur;

步骤4：选择主波波向φm附近的不同方向的所有的波向φp，p为波向φm附近的不同方向的所有波向的个数，并建立如下模型；Step 4: Select all wave directions φ p in different directions near the main wave direction φ m , where p is the number of all wave directions in different directions near the wave direction φ m , and establish the following model;

Figure GDA0003545122210000059
Figure GDA0003545122210000059

利用最小二乘法求解方程5，得出海流矢量

Figure GDA00035451222100000510
的值；Solving Equation 5 using the least squares method yields the current vector
Figure GDA00035451222100000510
the value of;

其中，cradar为波向

Figure GDA00035451222100000511
方向波浪的相速度，
Figure GDA00035451222100000512
ctheory为相速度的理论值，根据海浪的频散关系理论，得到
Figure GDA00035451222100000513
其中g为重力加速度；h为水深，
Figure GDA00035451222100000514
为海流矢量，Δt为相邻两幅图像的时间间隔，所有两幅图像之间的时间间隔均相同；
Figure GDA00035451222100000515
为波数矢量；Q＝1，2，3，...，p。Among them, c radar is the wave direction
Figure GDA00035451222100000511
the phase velocity of the directional waves,
Figure GDA00035451222100000512
c theory is the theoretical value of the phase velocity. According to the theory of the dispersion relation of ocean waves, we get
Figure GDA00035451222100000513
where g is the acceleration of gravity; h is the water depth,
Figure GDA00035451222100000514
is the current vector, Δt is the time interval between two adjacent images, and the time interval between all two images is the same;
Figure GDA00035451222100000515
is the wavenumber vector; Q=1, 2, 3, ..., p.

需要注意的是，所述步骤3中确定真实主波波数用于消除180度的方向模糊，选择真实主波波数的方法为：选择满足

Figure GDA0003545122210000061
的峰值波数
Figure GDA0003545122210000062
为真实的主波波数。It should be noted that the determination of the true main wave number in step 3 is used to eliminate the 180-degree direction blur, and the method for selecting the true main wave number is:
Figure GDA0003545122210000061
The peak wavenumber of
Figure GDA0003545122210000062
is the real main wave number.

所述步骤5中选择的波向φp，该波向φp同时满足下列要求：The wave direction φ p selected in the step 5, the wave direction φ p meets the following requirements at the same time:

1，φp的相干系数γ(k，φp)＞0.6，其中波数k满足：0.03≤k≤0.3tad/m；1. The coherence coefficient of φ p γ(k, φ p )>0.6, where the wave number k satisfies: 0.03≤k≤0.3tad/m;

2，|φp-φm|＜30°，

Figure GDA0003545122210000063
为主波波向。2, |φ p -φ m |＜30°,
Figure GDA0003545122210000063
Main wave direction.

如图2所示，利用一幅X波段雷达图像获得的海浪相速度与理论相速度的比较，可以看出二者具有较好的一致性，从而可以利用最小二乘法拟合得到矢量流场。As shown in Figure 2, the comparison between the wave phase velocity obtained by an X-band radar image and the theoretical phase velocity shows that the two have good consistency, so the vector flow field can be obtained by the least squares method.

Claims (3)

1.一种基于交叉谱分析的X波段雷达海流反演方法，其特征在于，包括如下步骤：1. a X-band radar ocean current inversion method based on cross-spectrum analysis, is characterized in that, comprises the steps: 步骤1：选取X波段雷达图像序列I，对相邻的两幅图像分别做交叉谱分析，得到相干系数
Figure FDA0003545122200000011
Step 1: Select the X-band radar image sequence I, and perform cross-spectrum analysis on the two adjacent images to obtain the coherence coefficient
Figure FDA0003545122200000011
Figure FDA0003545122200000012
Figure FDA0003545122200000012
 和相位
Figure FDA0003545122200000013
and phase
Figure FDA0003545122200000013
 Φij(k,φ)＝arg(Sij),i,j＝1,2,…,n (2)Φ ij (k, φ)=arg(S ij ),i,j=1,2,...,n (2) 其中Ii(x，y)是雷达图像的强度值，x和y为图像中点的横坐标和纵坐标，i和j为图像的序列，n为图像的数量，k与
Figure FDA0003545122200000014
组成频域坐标，K为波数，
Figure FDA0003545122200000015
为波向，Sij是图像Ii(x，y)与Ij(x，y)的功率谱，Sii为Ii(x，y)与其自身的功率谱，arg()表示取复数的辐角；where I i (x, y) is the intensity value of the radar image, x and y are the abscissa and ordinate of the point in the image, i and j are the sequence of images, n is the number of images, and k is the same as the
Figure FDA0003545122200000014
Composition frequency domain coordinates, K is the wave number,
Figure FDA0003545122200000015
is the wave direction, S ij is the power spectrum of the images I i (x, y) and I j (x, y), S ii is the power spectrum of I i (x, y) and itself, arg() represents the complex number argument; 步骤2：根据步骤1的相干系数
Figure FDA0003545122200000016
和相位
Figure FDA0003545122200000017
对所有相邻的图像做交叉谱分析，得到平均相干系数
Figure FDA0003545122200000018
Step 2: According to the coherence coefficient of step 1
Figure FDA0003545122200000016
and phase
Figure FDA0003545122200000017
Perform cross-spectral analysis on all adjacent images to obtain the average coherence coefficient
Figure FDA0003545122200000018
Figure FDA0003545122200000019
Figure FDA0003545122200000019
 和平均相位
Figure FDA00035451222000000110
and average phase
Figure FDA00035451222000000110
Figure FDA00035451222000000111
Figure FDA00035451222000000111
 步骤3：根据步骤1中的相干系数的峰值确定主波波数km，并利用步骤2中的平均相位确定真实主波波数用于消除180度的方向模糊；Step 3: Determine the main wave wave number km according to the peak value of the coherence coefficient in step 1, and use the average phase in step 2 to determine the real main wave wave number for eliminating the 180-degree direction blur; 步骤4：选择主波波向φm附近的不同方向的所有的波向φp，p为波向φm附近的不同方向的所有波向的个数，并建立如下模型；Step 4: Select all wave directions φ p in different directions near the main wave direction φ m , where p is the number of all wave directions in different directions near the wave direction φ m , and establish the following model;
Figure FDA0003545122200000021
Figure FDA0003545122200000021
 利用最小二乘法求解方程5，得出海流矢量
Figure FDA0003545122200000022
的值；Solving Equation 5 using the least squares method yields the current vector
Figure FDA0003545122200000022
the value of; 其中，cradar为波向
Figure FDA0003545122200000023
方向波浪的相速度，
Figure FDA0003545122200000024
ctheory为相速度的理论值，根据海浪的频散关系理论，得到
Figure FDA0003545122200000025
其中g为重力加速度；h为水深，
Figure FDA0003545122200000026
为海流矢量，Δt为相邻两幅图像的时间间隔，所有两幅图像之间的时间间隔均相同；
Figure FDA0003545122200000027
为波数矢量；Q＝1，2，3，…,p。Among them, c radar is the wave direction
Figure FDA0003545122200000023
the phase velocity of the directional waves,
Figure FDA0003545122200000024
c theory is the theoretical value of the phase velocity. According to the theory of the dispersion relation of ocean waves, we get
Figure FDA0003545122200000025
where g is the acceleration of gravity; h is the water depth,
Figure FDA0003545122200000026
is the current vector, Δt is the time interval between two adjacent images, and the time interval between all two images is the same;
Figure FDA0003545122200000027
is the wavenumber vector; Q=1, 2, 3, ..., p. 2.根据权利要求1所述的一种基于交叉谱分析的X波段雷达海流反演方法，其特征在于，所述步骤3中确定真实主波波数用于消除180度的方向模糊，选择真实主波波数的方法为：选择满足
Figure FDA0003545122200000028
的峰值波数
Figure FDA0003545122200000029
为真实的主波波数。2. a kind of X-band radar ocean current inversion method based on cross-spectrum analysis according to claim 1, is characterized in that, in described step 3, it is determined that the real main wave number is used to eliminate the direction blur of 180 degrees, select the real main wave number. The method of wave number is: choose to satisfy
Figure FDA0003545122200000028
The peak wavenumber of
Figure FDA0003545122200000029
is the real main wave number. 3.根据权利要求1所述的一种基于交叉谱分析的X波段雷达海流反演方法，其特征在于，所述步骤4中选择的波向φp，该波向φp同时满足下列要求：3. a kind of X-band radar ocean current inversion method based on cross-spectrum analysis according to claim 1, is characterized in that, the wave direction φ p selected in the described step 4, this wave direction φ p meets the following requirements simultaneously: 1,φp的相干系数γ(k,φp)＞0.6，其中波数k满足：0.03≤k≤0.3rad/m；1, the coherence coefficient of φ p γ(k, φ p )>0.6, where the wave number k satisfies: 0.03≤k≤0.3rad/m; 2,|φp-φm|＜30°，
Figure FDA00035451222000000210
为主波波向。2,|φ p -φ m |＜30°,
Figure FDA00035451222000000210
Main wave direction.
CN201811035048.0A 2018-09-06 2018-09-06 X-band radar ocean current inversion method based on cross spectrum analysis Active CN109283495B (en)

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