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1.
X-波段雷达近海海浪频谱反演的神经网络模型 总被引：2，自引：1，他引：1
X-波段雷达作为国内海浪观测的一种新工具,在海浪频谱获取和有效波高反演方面仍存在较多问题.本文利用非线性回归方法,将现场实测浮标数据频谱和雷达一维图像谱分别与标准频谱模型进行拟合,发现浮标频谱和一维图像谱具有标准频谱的特征,能够较准确地获取相应的谱参数.提出了建立由雷达一维图像谱参数反演海浪频谱参数的神经网络模型,同时在模型中加入影像序列信噪比,进而反演有效波高,并将反演结果与现场实测数据和传统算法(建立影像序列信噪比与有效波高之间的线性回归方程)进行了对比,结果表明,获取谱参数的误差和反演有效波高的平均误差在20％以内,而传统算法计算有效波高平均误差在20％以上. 相似文献
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基于相参X-波段海洋雷达的海表轮廓测量研究 总被引：4，自引：2，他引：2
X-波段海洋雷达测量所得海面散射单元的多普勒信息与散射单元的雷达视向速度密切相关。首先,基于符号多普勒估计方法,对X-波段雷达海面回波的多普勒频移信息进行了估计;在此基础上,应用各分辨单元回波的多普勒频移信息,建立了海浪表面轮廓的反演算法。该算法中,同时考虑了雷达入射角、方位角和雷达空间分辨率等因素对反演结果的影响。通过将反演结果与浮标测量数据相比较,发现雷达空间分辨率起到了类似低通滤波的作用,该作用对短重力波谱影响显著。同时,还应用加拿大麦克马斯特大学的IPIX雷达数据对海表轮廓进行了反演,并将反演所得有效波高、海浪周期与现场测量数据进行了比较,反演结果与现场测量结果吻合较好。 相似文献
3.
针对利用X波段海浪雷达回波图像反演海浪参数(波高、波向、波周期)的需要,而海浪雷达回波信号的采集和存储是利用雷达回波图像序列反演海浪参数的必要前提,提出了基于PXI-9280 A/D采集卡对X波段海浪雷达回波进行采集的方案.具体介绍了PXI-9280 A/D采集卡的功能特性,海浪雷达回波信号样式,设计并完成了基于VC 6.0的采集和存储软件,并对使用该采集卡需要注意的实际问题给予说明.此外,还搭建了实验平台,给出了基于PXI-9280 A/D采集卡在我国南海某海域中采集数据并回放得到的海浪雷达回波图像,得到较满意的结果. 相似文献
4.
降雨条件下的导航X波段雷达海浪参数反演算法研究 总被引：1，自引：0，他引：1
X波段的电磁波受降雨影响容易产生衰减,这导致导航X波段雷达在降雨时无法用于海浪观测。本文提出了一种新的降低降雨影响的算法来反演海浪参数。首先,对X波段雷达图像做主成分分析,获得波浪变化的主成分,利用一维傅里叶变换得到波数谱,对其滤波减小降雨对雷达图像的影响;然后,选取JONSWAP(Joint North Sea Wave Project)谱作为理论谱,建立以观测谱与理论谱的最小化差异为目标函数的模型,求解该模型估算海浪的有效波高。与浮标测量的有效波高相比,该方法反演的有效波高的均方根误差是0.23 m,证明了该方法的可行性。 相似文献
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本文根据相干斑噪声的时间快变特征和非海浪纹理现象的时间缓变特征，基于交叉谱提出了一种对相干斑噪声和大尺度非海浪纹理的抑制的方法，进而结合SAR图像谱和海浪谱之间的准线性映射关系，基于SAR数据对海浪参数进行了反演。在反演过程中，首先仿真分析了不同海况下准线性近似法的海浪反演能力，结果表明：风浪引起的方位向截断效应会显著影响反演精度，因此该方法在低风速时的涌浪反演精度更高。通过将基于Sentinel-1卫星2020年的波模式SAR数据的反演结果与欧洲中期天气预报中心(European Centre for Medium-Range Weather Forecasts, ECMWF)提供的再分析数据进行对比，发现高海况海浪有效波高反演结果明显偏低，而且该反演误差与风速、方位向截断波长之间存在显著相关性。为了提高有效波高的反演精度，本文进一步给出了海浪有效波高反演误差与风速、方位向截断波长之间的经验校正函数模型，结果显示，通过该模型修正后的海浪有效波高反演结果与ECMWF数据和浮标测量数据具有良好一致性。 相似文献
6.
浪向代表着海浪传播方向，它是海上交通安全以及海岸资源管理的重要海洋环境参数之一。本文针对X波段测波雷达对海杂波的连续成像，提出了一种基于光流法的海浪传播方向反演新方法。该方法利用X波段测波雷达接收的海面回波图像序列直接进行光流运动估计，将得到的每个像素点的运动矢量进行加权平均，最后得到实际的海浪传播方向。与传统基于频域的X波段测波雷达浪向反演方法相比，本文提出的方法直接从时域来进行回波信号处理，无需提前得到调制传递函数以及精确的海流，减少了由于海流估算的不准确以及调制传递函数选取的误差而给雷达浪向反演带来的影响。同时，该方法简单高效，占用资源少，将其应用至仿真雷达回波以及现场实测数据来进行浪向反演，反演得到的浪向与仿真设定浪向值以及浮标实时观测浪向结果都有很好的吻合度，变化趋势也完全一致，进而验证了该方法的有效性以及准确性。 相似文献
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针对斑点噪声降低机载波谱仪海浪谱反演精度问题,基于STORM机载波谱仪VALPARESO试验数据,分别使用数学法、阈值法、交叉谱法和小波分析法四种斑点噪声去除方法对其进行去噪处理,得到了去噪前后调制密度谱、海浪谱和噪声谱,并将反演所得海浪谱有效波高与同步观测的浮标结果进行了对比,最后对四种方法的去噪效果以及噪声谱特性进行了分析与评价。结果表明:四种去噪方法均可以有效去除斑点噪声,按照反演精度排序依次为交叉谱法、阈值法、小波分析法和数学法,其中交叉谱方法去噪效果最理想,RMSE仅为0.008,有效波高绝对误差为0.25m,相对误差为7%。 相似文献
11.
A joint airborne measurement program is being pursued by NRL and NASA Wallops Flight Center to determine the extent to which wind speed and sea surface significant wave height (SWH) can be measured quantitatively and remotely with a short pulse (2 ns), wide-beam (60deg ), nadir-looking 3-cm radar. The concept involves relative power measurements only and does not need a scanning antenna, doppler filters, or absolute power calibration. The slopes of the leading and trailing edges of the averaged received power for the pulse limited altimeter are used to infer SWH and surface wind speed. The interpretation is based on theoretical models of the effects of SWH on the leading edge shape and rms sea-surface slope on the trailing-edge shape. The models include the radar system parameters of antenna beam width and pulsewidth. Preliminary experimental results look promising and indicate that it may be possible to design a relatively compact airborne radar to infer, in real-time, the sea surface SWH and surface wind speed. 相似文献
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本文首先对合成孔径雷达（SAR）海浪成像中的3种调制（倾斜调制、流体力学调制与速度聚束调制）的影响进行了对比分析,结果显示:速度聚束调制对SAR图像的影响最为显著。另外,由于SAR图像中固有相干斑噪声的存在,较低波数范围的噪声难以滤除或抑制,利用经典MPI方法反演海浪谱会造成低波数范围谱值偏大。基于此,本文借鉴经典MPI海浪谱反演算法,建立了基于速度聚束调制的海浪方位向斜率谱和有效波高的反演算法。通过将经典MPI方法、同极化调制法及本文算法等3种海浪反演方法所得有效波高与浮标数据进行比较,结果显示:本文方法反演得到的海浪有效波高与浮标数据获得的有效波高之间的均方误差为0.79 m,为3种方法中最小。 相似文献
13.
基于CCMP卫星遥感海面风场数据的渤海风浪模拟研究 总被引：6，自引：0，他引：6
CCMP（Cross Calibrated Multi-Platform）风场数据是一种具有较高的时间、空间分辨率和全球海洋覆盖能力的新型卫星遥感资源。在充分分析CCMP海面风场数据可靠性的基础上,以该卫星遥感海面风场数据为强迫输入项,运用第三代浅水波浪模式SWAN对渤海一次风浪过程进行了模拟,将模拟的结果与T/P、Jason卫星高度计观测得到的有效浪高数据进行比较分析,发现两者相关性达到0.78,模拟结果平均偏高0.3 m。试验表明CCMP卫星遥感风场数据能满足海洋浪高预报需求,能在海洋数值预报和海洋环境研究中发挥重要作用。 相似文献
14.
The significant wave height (SWH) is one of the main parameters that describe wave characteristics and is widely used in wave research fields. Wave parameters measured by radar are influenced by the offshore distance and sea state. Validation and calibration are of great significance for radar data applications. The nadir beam of surface wave investigation and monitoring (SWIM) detects the global-ocean-surface SWH. To determine the product quality of SWIM SWH, this paper carried out time-space matching between SWIM and buoy data. The data qualities were evaluated under different offshore distances and sea states. An improved calibration method was proposed based on sea state segmentation, which considered the distribution of the point collocation numbers in various sea states. The results indicate that (1) the SWIM SWH accuracy at offshore distances greater than 50 km is higher than that at distances less than 50 km, with an root mean squared error (RMSE) of 0.244 4 m, scatter index (SI) of 0.115 6 and relative error (RE) of 9.97% at distances greater than 50 km and those of 0.446 0 m, 0.223 0 and 18.66% at distances less than 50 km. (2) SWIM SWH qualities are better in moderate and rough sea states with RMSEs of 0.284 8 m and 0.316 9 m but are worse in slight and very rough sea states. (3) The effect of the improved calibration method is superior to the traditional method in each sea state and overall data, and the RMSE of SWIM SWH is reduced from the raw 0.313 5 m to 0.285 9 m by the traditional method and 0.198 2 m by the improved method. The influence of spatiotemporal window selection on data quality evaluation was analyzed in this paper. This paper provides references for SWIM SWH product applications. 相似文献
15.
We present the results of retracking 18 cycles (15 from the Jason-TOPEX collinear period) of Jason-1 data. We used the retracking method of Rodriguez which simultaneously solves for all relevant waveform parameters using a 26 Gaussian model of the altimeter point target response. We find significant differences from the Jason-1 Project retracking in the key parameters of range and significant wave height (SWH) in the second version of the Project SGDRs. The differences from the Jason-1 data have a strong dependence on off-nadir angle and some dependence on SWH. The dependence of range on SWH is what is called sea state bias. The retracking technique also estimates surface skewness. For Jason-1 with its very clean waveforms we make the first direct estimates of the skewness effect on altimeter data. We believe that the differences found here and thus in overall sea surface height are the result of the standard project processing using a single Gaussian approximation to the Point Target Response (PTR) and not solving simultaneously for off nadir angle. We believe that the relatively large sea state bias errors estimated empirically for Jason-1 during the cal/val phase result from sensitivity of quantities, particularly SWH, in project GDRs to off nadir angle. The TOPEX-Jason-1 bias can be determined only when a full retracking of Jason-1 is done for the collinear period. 相似文献
16.
We show that the parameters of primary radar images obtained from theSich-1 satellite depend on the mode of survey and that the time dependence of the coefficient of correction of amplification in
the channel of formation of radar signals is nonlinear. We propose to process radar images of the sea surface by using the
so-called Bragg normalization of signals, which enables one to get a physically correct dependence of specific effective scattering
surface on the elevation angle. We also consider a procedure of determination of the dependence of specific effective scattering
surface of the sea on the wind velocity on the basis of the data accumulated by the side-looking radar of theSich-1 satellite.
Translated by Peter V. Malyshev and Dmitry V. Malyshev 相似文献
17.
Retracking of Jason-1 Data 总被引：1，自引：0，他引：1
We present the results of retracking 18 cycles (15 from the Jason-TOPEX collinear period) of Jason-1 data. We used the retracking method of Rodriguez which simultaneously solves for all relevant waveform parameters using a 26 Gaussian model of the altimeter point target response. We find significant differences from the Jason-1 Project retracking in the key parameters of range and significant wave height (SWH) in the second version of the Project SGDRs. The differences from the Jason-1 data have a strong dependence on off-nadir angle and some dependence on SWH. The dependence of range on SWH is what is called sea state bias. The retracking technique also estimates surface skewness. For Jason-1 with its very clean waveforms we make the first direct estimates of the skewness effect on altimeter data. We believe that the differences found here and thus in overall sea surface height are the result of the standard project processing using a single Gaussian approximation to the Point Target Response (PTR) and not solving simultaneously for off nadir angle. We believe that the relatively large sea state bias errors estimated empirically for Jason-1 during the cal/val phase result from sensitivity of quantities, particularly SWH, in project GDRs to off nadir angle. The TOPEX-Jason-1 bias can be determined only when a full retracking of Jason-1 is done for the collinear period. 相似文献
18.
利用机器学习的方法,对14个周期HY-2A卫星高度计数据:风速、有效波高和海面高度差值进行训练,探究海况偏差和风速、有效波高之间的关系,创建海况偏差核函数非参数模型(NPSSB),并与参数模型中具有代表性的BM3、BM4模型进行对比。研究表明:(1)核函数NPSSB模型能够很好的反映SSB与U、SWH之间的关系,SSB与U呈二次函数关系,SSB与SWH呈反比例函数关系;(2)核函数NPSSB模型对SSB的模拟能力与训练数据集相关,数据量越多,模拟能力越好;(3)核函数NPSSB模型与BM3、BM4模型都存在0^-0.03 m的差值,随着风速和有效波高的增加,差值的绝对值越大。 相似文献
19.
The main objective of this paper is to propose a newly developed ocean Significant Wave Height(SWH) retrieval method from Envisat Advanced Synthetic Aperture Radar(ASAR) imagery. A series of wave mode imagery from January, April and May of 2011 are collocated with ERA-Interim reanalysis SWH data. Based on the matched datasets, a simplified empirical relationship between 22 types of SAR imagery parameters and SWH products is developed with the Genetic Algorithms Partial Least-Squares(GA-PLS) model. Two major features of the backscattering coefficient σ_0 and the frequency parameter S_(10) are chosen as the optimal training feature subset of SWH retrieval by using cross validation. In addition, we also present a comparison of the retrieval results of the simplified empirical relationship with the collocated ERA-Interim data. The results show that the assessment index of the correlation coefficient, the bias, the root-mean-square error of cross validation(RMSECV) and the scattering index(SI) are 0.78, 0.07 m, 0.76 m and 0.5, respectively. In addition, the comparison of the retrieved SWH data between our simplifying model and the Jason-2 radar altimeter data is proposed in our study.Moreover, we also make a comparison of the retrieval of SWH data between our developed model and the wellknown CWAVE_ENV model. The results show that satisfying retrieval results are acquired in the low-moderate sea state, but major bias appears in the high sea state, especially for SWH5 m. 相似文献
20.
Hirofumi Hinata Satoshi Fujii Keita Furukawa Tomoya Kataoka Masafumi Miyata Takashi Kobayashi Masahiro Mizutani Takahiro Kokai Nobuyoshi Kanatsu 《Estuarine, Coastal and Shelf Science》2011
Signals from the tsunami waves induced by the March 11, 2011 moment magnitude (Mw) 9.0 Tohoku-Oki earthquake and from subsequent resonances were detected as radial velocity variability by a high-frequency ocean surface radar (HF radar) installed on the eastern coast of the Kii Channel, at a range of about 1000 km from the epicenter along the eastern to southern coasts of Honshu Island. A time–distance diagram of band-passed (9–200 min) radial velocity along the beam reveals that the tsunami waves propagated from the continental shelf slope to the inner channel as progressive waves for the first three waves, and then natural oscillations were excited by the waves; and that the direction of the tsunami wave propagation and the axis of the natural oscillations differed from that of the radar beam. In addition, spectral analyses of the radial velocities and sea surface heights obtained in the channel and on the continental shelf slope suggest complex natural oscillation modes excited by the tsunami waves. 相似文献