Estimation of Directional Wave Spectra from HF Radar Sea Echo Doppler Spectra
Estimation of Directional Wave Spectra from HF Radar Sea Echo Doppler Spectra
复制标题
从高频雷达海回波多普勒频谱估计定向波频谱
DOI：
10.1142/9789812791306_0010
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发表时间：
2003
影响因子：
--
通讯作者：
Yuji Sato
中科院分区：
文献类型：
--
作者：
S. Kojima;N. Hashimoto;Yuji Sato
利用海洋雷达测量海面海流已成为现实。事实上，对沿岸带海流的许多观测已经提供了相当有价值的结果。与此形成对比的是，海洋雷达对海浪的测量还处于理论水平。贝叶斯估计可以应用于从多普勒谱获得方向波谱。这种方法在理论上是适用的，但是噪声污染了测量的多普勒频谱，使得它们显著偏离理想。贝叶斯估计仅依赖于二阶后向散射分量，但从观测到的多普勒频谱的方向波谱的准确估计需要多普勒频谱的一阶和二阶后向散射分量的适当分离;这是一项艰巨的任务，因为观测到的多普勒频谱的种类繁多。讨论了一种应用小波多分辨率分析分离出光谱的一阶和二阶后向散射分量的方法。此外，一种新的方法，我们适用于第一和第二阶后向散射分量，以获得具有更好的分辨率的方向波谱描述。最后，高频海洋雷达设施沿着鹿岛海岸被用来进行一系列的现场测量的多普勒频谱，从其中的方向波谱，然后估计。同时进行了观测与波计阵列，随后的比较表明，从高频海洋雷达观测得到的结果很好的协议。
The use of oceanic radar to measure currents at the sea's surface has become practicable. Many observations of currents in coastal zones have, in fact, provided quite worthwhile results. In contrast to this, the measurement of ocean waves by oceanic radar is still at the theoretical level. Bayesian estimation may be applied to obtain directional wave spectra from Doppler spectra. This method is, in theory, applicable, but noise contaminates the measured Doppler spectra so that they deviate significantly from the ideal. Bayesian estimation relies solely on second-order backscattering components, yet accurate estimation of directional wave spectra from observed Doppler spectra requires the proper separation of the first- and second-order backscattering components of the Doppler spectra; this is a difficult task because of the great variety of observed Doppler spectra. A method where we apply wavelet multiple-resolution analysis to separate out the first- and second-order backscattering components of the spectra is discussed. In addition, a new method where we apply both the first- and second-order backscattering components to obtain directional wave spectra that have better resolution is described. Finally, HF oceanic-radar facilities along the Kashima coast were used to conduct a series of field measurements of Doppler spectra, from which the directional wave spectra were then estimated. Simultaneous observations were made with a wave-gage array, and subsequent comparison showed good agreement with the results obtained from the HF oceanic radar observations.