【摘要】：表層流是海洋中重要的運(yùn)動(dòng)現(xiàn)象,了解和掌握表層流的運(yùn)動(dòng)規(guī)律,將有助于研究海洋表層流的形成、成長、傳播以及衰退等機(jī)制,也對近岸區(qū)域的水產(chǎn)業(yè)、運(yùn)輸業(yè)以及排污等意義重大。目前已經(jīng)有許多的表層流探測設(shè)備,其中,微波多普勒雷達(dá)具有時(shí)空分辨率高、抗干擾性能好、全天候工作、體積小等優(yōu)點(diǎn),應(yīng)用前景良好。本文基于武漢大學(xué)無線電海洋遙感實(shí)驗(yàn)室獨(dú)立研發(fā)的S波段多普勒雷達(dá)為平臺(tái),針對海洋表層流信息提取方法進(jìn)行了研究,擴(kuò)展S波段多普勒雷達(dá)的探測功能。S波段多普勒雷達(dá)發(fā)射的電磁波與海表面的毛細(xì)波產(chǎn)生布拉格散射,而小尺度的毛細(xì)波受大尺度重力波的調(diào)制作用,攜帶著重力波的特征信息�；谥亓Σl率與波數(shù)的耗散關(guān)系,可以提取表層流信息。目前基于微波多普勒雷達(dá)表層流信息提取的研究有雙頻測流技術(shù)和速度序列時(shí)間平均的方法,對于岸基單站S波段多普勒雷達(dá)提取表層流的研究,本文根據(jù)重力波頻率與波數(shù)的耗散關(guān)系,通過對雷達(dá)測量的二維徑向速度序列進(jìn)行處理,提取表層流信息。論文首先介紹了 S波段多普勒雷達(dá)的表層流信息提取算法:通過對雷達(dá)測量的二維徑向速度序列進(jìn)行二維傅里葉變換得到頻率波數(shù)譜,計(jì)算得到功率譜后,提出帶通濾波結(jié)合自適應(yīng)閾值的方法選擇離散的待擬合數(shù)據(jù)點(diǎn),依據(jù)重力波頻率與波數(shù)的耗散關(guān)系,基于加權(quán)最小二乘原則可以擬合得到重力波耗散關(guān)系曲線,從而提取徑向流速值。通過雷達(dá)六根天線數(shù)據(jù)提取的六個(gè)徑向流速值,可以合成矢量流,得到流速和流向信息。然后基于表層流提取算法,進(jìn)行了仿真分析,基于仿真數(shù)據(jù)驗(yàn)證了算法的正確性。通過已知的海浪譜模型,并且將表層流因素考慮進(jìn)去,可以仿真得到加入表層流信息的二維徑向速度�；诜抡鏀�(shù)據(jù),采用單天線徑向流速提取算法與合成矢量流的方法,計(jì)算得到的結(jié)果與理論值的誤差很小,仿真結(jié)果表明算法正確。最后通過對S波段多普勒雷達(dá)實(shí)測的數(shù)據(jù)進(jìn)行處理,來提取表層流信息。針對實(shí)測數(shù)據(jù)中存在奇異點(diǎn)的問題,通過分析時(shí)空二維多普勒譜參數(shù)的特征,提出先時(shí)間后空間去除奇異點(diǎn)的數(shù)據(jù)預(yù)處理方法,其中空間采用滑窗自適應(yīng)門限檢測奇異點(diǎn)。數(shù)據(jù)預(yù)處理后,由單天線實(shí)測數(shù)據(jù)可以提取徑向流速值,利用提取的六天線徑向流速值可以合成矢量流。結(jié)合遮浪島和朱家尖的實(shí)測數(shù)據(jù),采用多點(diǎn)數(shù)據(jù)分析和全天數(shù)據(jù)分析,結(jié)果表明算法具有可行性。
[Abstract]:Surface current is an important movement phenomenon in the ocean. Understanding and mastering the motion law of surface current will be helpful to study the formation, growth, propagation and decline of ocean surface current, and also to aquatic industry in coastal area. Transportation and sewage are of great significance. At present, there are many surface current detection equipments, among which microwave Doppler radar has the advantages of high space-time resolution, good anti-jamming performance, all-weather operation, small volume and so on. Based on the S-band Doppler radar developed independently by the Radio Marine remote Sensing Laboratory of Wuhan University, this paper studies the method of extracting ocean surface current information. The electromagnetic wave emitted by S band Doppler radar and the capillary wave on the sea surface produce Bragg scattering, while the small scale capillary wave is modulated by the large scale gravity wave. Carries the characteristic information of gravity waves. Based on the dissipative relation between gravity wave frequency and wave number, surface flow information can be extracted. At present, the research based on microwave Doppler radar surface laminar flow information extraction has dual-frequency current measurement technology and velocity series time averaging method, for shore-based single-station S-band Doppler radar extraction of surface flow. According to the dissipative relation between the frequency of gravity wave and the wave number, the surface flow information is extracted by processing the two-dimensional radial velocity series measured by radar. Firstly, the paper introduces the surface flow information extraction algorithm of S-band Doppler radar. The frequency wavenumber spectrum is obtained by the two-dimensional Fourier transform of the two-dimensional radial velocity series measured by the radar, and the power spectrum is obtained by calculating the power spectrum. The method of bandpass filter combined with adaptive threshold is proposed to select discrete data points to be fitted. According to the dissipative relation between the frequency of gravity wave and the number of waves, the curve of dissipation relation of gravity wave can be fitted based on the weighted least square principle. Thus the radial velocity is extracted. The vector flow can be synthesized from the six radial velocity values extracted from the data of six radar antennas and the information of velocity and flow direction can be obtained. Then, based on the surface flow extraction algorithm, the simulation analysis is carried out, and the correctness of the algorithm is verified based on the simulation data. Based on the known wave spectral model and taking into account the surface flow factors, the two-dimensional radial velocity with the surface current information can be simulated. Based on the simulation data, the radial velocity extraction algorithm of single antenna and the synthetic vector flow method are adopted. The error between the calculated results and the theoretical values is very small. The simulation results show that the algorithm is correct. Finally, the surface flow information is extracted by processing the measured data of S band Doppler radar. In order to solve the problem of singularity in measured data, by analyzing the characteristics of space-time two-dimensional Doppler spectral parameters, a new method of data preprocessing is proposed, in which the sliding window adaptive threshold is used to detect singularities. After data preprocessing, the radial velocity can be extracted from the measured data of single antenna, and the vector flow can be synthesized by using the extracted radial velocity of six antennas. Combined with the measured data of Yalang Island and Zhu Jia-jian, the multi-point data analysis and all-day data analysis are used. The results show that the algorithm is feasible.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TN958

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