Measurement of long waves at the harbor of Marina di Carrara, Italy
Measurement of long waves at the harbor of Marina di Carrara, Italy
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DOI：
10.1007/s10236-011-0468-6
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发表时间：
2011-08
期刊：
影响因子：
2.3
通讯作者：
G. Bellotti;L. Franco
中科院分区：
文献类型：
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作者：
G. Bellotti;L. Franco
本文介绍了意大利卡拉拉码头长波测量结果的分析。使用9个压力计（8个在港内，1个在港外）连续记录水面高程，持续约3年；使用距防波堤约 500 m 处的定向浮标测量传入的短波。将长波的能量分为两个频段进行分析，即甚长波（VLW；f< 0.003 Hz）和长波（LW；0.003 <f< 0.030 Hz）；结果发现，LW 能量与入射短波的能量密切相关，而 VLW 则没有发现相关性（或非常差）。在高能海况期间，VLW 和 LW 的表面高程谱（根据每个频带的波浪能量归一化）似乎是自相似的；这表明入射长波的光谱具有基本恒定的形状。使用温和斜率方程线性化模型进行的港口共振的简单数值计算表明，假设长波谱是矩形，可以使用这种简单的方法合理地预测港口内短波产生的传入长波高度的放大（使用 Melito 等人 2007 年先前研究的经验公式计算）。由数值模型计算的放大图的形状与港口内归一化测量光谱的形状显示出合理（但不完美）的一致性。
This paper presents the analysis of measurements of long waves at the harbor of Marina di Carrara, Italy. Nine pressure gauges (eight in the inner harbor and one outside the harbor) were used to record continuously the water surface elevation, for about 3 years; incoming short waves were measured using a directional buoy at about 500 m offshore the breakwaters. The analysis is carried out splitting the energy of the long waves into two bands, i.e., very long waves (VLW;f< 0.003 Hz) and long waves (LW; 0.003 <f< 0.030 Hz); it is found that LW energy is strongly correlated with the energy of the incoming short waves while no correlation (or very poor) is found for VLW. During energetic sea states, surface elevation spectra of VLW and LW, normalized against the wave energy of each frequency band, appear to be autosimilar; this suggests that the spectra of the incoming long waves have a mostly constant shape. Simple numerical computations of harbor resonance, carried out using a mild-slope equation linearized model, indicate that the amplification of the height of the incoming LW generated by short waves (calculated using empirical formulae from previous researches by Melito et al. 2007) inside the harbor can be reasonably predicted using such simple approach, assuming that the LW spectra are rectangular. The shape of the amplification diagram calculated by the numerical model shows reasonable (but not perfect) agreement with the shape of the normalized measured spectra inside the harbor.