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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
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海面电磁回波频谱宽度与海浪波高密切相关,可应用频谱宽度进行海浪有效波高反演。本文应用线性滤波法仿真出了海表散射面元在雷达视向上的投影速度,建立了回波谱宽模型,分析了雷达空间分辨率、回波时间序列长度及海洋环境参数等因素对频谱宽度的影响,同时还针对如何在实际观测过程中选择回波时间序列长度、观测方位角等参数进行了讨论。最后还将理论结果与CSIR-X波段雷达实测数据谱宽估计结果进行了比较。结果表明,剔除雷达噪声以及频率泄露的影响后,基于高斯分布标准偏差的谱宽估计方法所得结果与理论结果吻合很好,这从而证明了理论结果的可靠性。本文所得结果对海浪有效波高反演具有一定参考价值。 相似文献
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海浪波高测量是海洋勘探的主要内容之一.结合Ku波段多普勒相栓雷达,运用虚拟仪器根据海浪回波的多普勒频率来判断海浪变化,测出海浪波高存储数据.系统硬件部分采用了NJ(National Instruments 美国国家仪器)公司的高性能数据采集卡USB-6251.替代传统的DSP处理芯片.软件方面采用了Labview7.1图形化编程实现,具有很好的直观性和形象性.初步实现了潮位测量的基本功能. 相似文献
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海浪是影响舰船行进和结构设计的最核心的环境要素。海浪参数的统计分析是建立舰船环境适应性长期预测模型的基础。对1993-2011年沿海台站、浮标观测资料,高度计观测资料和船舶报观测资料进行双线性插值,给出了海浪波高的分析场。利用波高分析场对WAVEWATCHIII(WW3)模拟结果进行最优插值同化。给出了海浪统计玫瑰图、极端海浪统计参数和海浪累年二维极值海浪谱等与舰船耐波性有关的海浪统计参数,分析了中国近海的波浪特征。 相似文献
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为了验证波谱仪反演二维海浪谱的功能,根据海浪波谱仪的信号形成机制,总结了机载波谱仪反演海浪的流程。利用机载波谱仪回波数据,通过自相关和互相关两种功率谱估计方法,反演了二维海浪谱。最后通过与浮标测量的二维海浪谱进行对比,验证了该机载波谱仪探测二维海浪谱的有效性。结果表明,无论采用自相关函数还是互相关函数进行功率谱估计,得到的主波波长和有效波高与实际二维海浪谱基本一致。互相关函数法得到的交叉谱能去除180°模糊现象,其在计算有效波高时相对于自相关函数会稍微偏小。在计算斜率方差时可以采用5°~12°入射角范围的后向散射系数进行公式拟合,因此定标与否并不影响最后的二维海浪谱结果,未来星载波谱仪只有靠多波束联合才能实现。 相似文献
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海浪是海洋工程中的重要海洋环境参数之一,故而是海洋工程测量的主要工作之一。海洋工程中的设计波浪要素,一是可根据长期实测海浪资料进行推算,二是在缺乏资料时,利用历史天气资料推求设计海浪要素,即海浪后报。 本文提供的海浪后报方法,不仅将Wilson方法的数学模型编制成计算机源程序,避免了查那些复杂的诺模图,而且对其进行了改进,从而大大提高了工效和计算结果的精度。同时,以实例加以说明,本文提供的方法是切实可行的。 相似文献
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船用X波段导航雷达凹波形成的海杂波图像中包含丰富的海浪、海表层流信息.借鉴合成孔径雷达(SAR)估计有效波高的方法,假设有效波高与雷达回波强度信噪比的平方根成线性关系,可由X波段雷达图像估计得到海浪的有效波高.用此方法主要分析小麦岛海域实验数据,结果显示,直流滤波后计算的信噪比估计的有效波高比不进行直流滤波结果符合得好;而按波浪浮标测得有效波高数据的高低,分两段分别进行线性拟合获取校准系数,估测的有效波高更加准确. 相似文献
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Recent experimental and theoretical findings raise interesting questions about the applicability of the normal gravity-wave dispersion relation at wave frequencies that exceed the spectral peak frequency. The use of the dispersion relation in analysis of HF radar Doppler sea echo is examined in this paper. Drawing on the results of perturbation theory for wave-wave nonlinear interactions, we show that this relation, so essential to echo interpretation in terms of current and wave information, can be employed with no degradation in accuracy for current measurement when the dominant wave frequency is considerably less (by as much as 10) than the radar Bragg resonance frequency. This finding is supported by comparisons of currents measured by HF radar with "surface truth;" the first-order echo must only be identifiable in order to be used accurately. Wave-height directional spectral information can be extracted from the second-order echo at a given radar frequency up to the point (in wave height) where the perturbation solution employed in the inversion process fails; then a lower radar frequency must be used. On the other hand, most conventional wave measuring instruments should not use the dispersion relation for interpretation of data well beyond the spectral peak, because they do not observe wave height as a function of both space and time independently, as does HF radar. 相似文献
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Lipa B.J. Barrick D.E. Isaacson J. Lilleboe P.M. 《Oceanic Engineering, IEEE Journal of》1990,15(2):119-125
CODAR, a high-frequency (HF) compact radar system, was operated continuously over several weeks aboard the semisubmersible oil platform Treasure Saga for the purpose of wave-height directional measurement and comparison. During North Sea winter storm conditions, the system operated at two different frequencies, depending on the sea state. Wave data are extracted from the second-order backscatter Doppler spectrum produced by nonlinearities in the hydrodynamic wave/wave and electromagnetic wave/scatter interactions. Because the floating oil rig itself moves in response to long waves, a technique has been developed and successfully demonstrated to eliminate to second order the resulting phase-modulation contamination of the echo, using separate accelerometer measurement of the platform's lateral motions. CODAR wave height, mean direction, and period are compared with data from a Norwegian directional wave buoy; in storm seas with wave heights that exceeded 9 m, the two height measurements agreed to within 20 cm RMS, and the mean direction to better than 15° RMS 相似文献
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ADCP application for long-term monitoring of coastal water 总被引:3,自引:1,他引:2
Three kind of application of ADCP is reported for long-term monitoring in coastal sea. (1)The routine monitoring of water qualities. The water quality and ADCP echo data (600 kHz) observed in the long-term are analgzed at MT (Marine Tower) Station of Kansai International Airport in the Osaka Bay, Japan. The correlation between the turbidity and echo intensity in the surface layer is not good because air bubbles generated by breaking wave are not detected by the turbidity meter, but detected well by ADCP. When estimating the turbidity consists ofplankrton population from echo intensity, the effect of bubbles have to be eliminated. (2) Monitoring stirring up of bottom sediment. The special observation was carried out by using following two ADCP in the Osaka Bay, One ADCP was installed upward on the sea. The other ADCP was hanged downward at the gate type stand about 3 m above from the bottom. At the spring tide, high echo intensities indicating the stirring up of bottom sediment were observed. (3) The monitoring for the boundary condition of water mixing at an estuary. In summer season, the ADCP was set at the mouth of Tanabe Bay in Wakayama Prefecture, Japan. During the observation, water temperature near the bottom showed remarkable falls with interval of about 5~7d. When the bottom temperature fell, the inflow current with low echo intensity water appears at the bottom layer in the ADCP record. It is concluded that when occasional weak northeast wind makes weak coastal upwelling at the mouth of the bay, the combination ofupwelling with internal tidal flow causes remarkable water exchange and dispels the red tide. 相似文献
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An experimental method to investigate submarine bedform signatures at the sea surface is described. The study area was the Lister Tief in the German Bight of the southeastern North Sea, a semienclosed tidal basin with asymmetric and very large sand waves. In-situ and remote measurements of surface roughness were obtained simultaneously. An X-band wave monitoring radar, an oceanographic multisensor sea surface buoy, an acoustic Doppler current profiler, and a standard echo sounder were operated on and from board a research vessel while drifting along the tidal channel 相似文献
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A. G. Luchinin 《Izvestiya Atmospheric and Oceanic Physics》2012,48(6):663-671
The main effects accompanying the propagation of an initially narrow complex modulated light beam in sea water are studied. Sea water, with respect to modulation waves, is shown to be similar to a medium with frequency dispersion with respect to electromagnetic waves; in the medium, the effects of the time focusing of a wave packet are possible. Based on the self-similar small-angle solution to the equation of radiation transfer, we estimate spatial-temporal characteristics of pulse-signal amplitude modulated by a complex signal. We propose a scheme for constructing underwater LIDAR using a complex modulated illumination beam and the processing of a received echo signal. The processing allows the separation of the modulated component and its matched filtration. Values of possible delays and broadening of the separated echo signal caused by dispersion properties of sea water are estimated. 相似文献
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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