A novel technique for experimental modal analysis of barotropic seiches for assessing lake energetics
A novel technique for experimental modal analysis of barotropic seiches for assessing lake energetics
复制标题
DOI：
10.1007/s10652-019-09677-x
复制
发表时间：
2019-03
影响因子：
2.2
通讯作者：
Zachariah Wynne;Thomas Reynolds;D. Bouffard;G. Schladow;D. Wain
中科院分区：
文献类型：
--
作者：
Zachariah Wynne;Thomas Reynolds;D. Bouffard;G. Schladow;D. Wain
湖泊中的流域尺度假潮是总能量收支的重要组成部分，也是重要生态参数（如氧气、营养盐和沉积物）通量的驱动因素。目前，提取的阻尼比的表面假潮，这是直接关系到的能力，假潮驱动这些通量通过增加混合的水柱，是依赖于频谱分析，这可能会受到严重影响的水位记录从时域到频域的转换，这是敏感的数据内存在的噪声水平。现有的基于光谱的方法很难提取周期的表面假潮是相似的幅度，由于它们的光谱响应之间的重叠。在这项研究中，操作模态分析的原则，通过随机减量技术（RDT），目前主要用于高层建筑物的分析，并在航空工业和以前没有应用在湖沼学或生态学领域，适用于正压假潮通过分析水位数据日内瓦，瑞士和太浩湖，美国。使用这种技术，估计使用RDT和模态分析的测量值的自相关性，然后可以在这个时域信号进行估计的主导表面假潮和相应的阻尼比的周期。通过传统的频谱技术和一致的阻尼比获得的主导表面的太浩湖假潮的估计周期与实验结果显示出良好的一致性。输入参数的影响进行了讨论，使用的两个湖泊的数据，以及讨论RDT的应用程序的内部假潮的研究和当前的障碍，其应用。RDT具有很大的潜力，表面和内部假潮的分析，提供了一种方法，通过它可以获得准确的阻尼比假潮振荡使用现成的数据，而不需要频谱分析。
Basin scale seiches in lakes are important elements of the total energy budget and are a driver of fluxes of important ecological parameters, such as oxygen, nutrients, and sediments. At present, the extraction of the damping ratios of surface seiches, which are directly related to the capacity of seiches to drive these fluxes through the increased mixing of the water column, is reliant on spectral analysis which may be heavily influenced by the transformation of water level records from the time domain to the frequency domain, and which are sensitive to the level of noise present within the data. Existing spectral-based methods struggle to extract the periods of surface seiches which are of similar magnitude due to the overlap between their spectral responses. In this study, the principles of operational modal analysis, through the random decrement technique (RDT), currently used primarily in the analysis of high rise structures and in the aeronautical industry and not previously applied within the fields of limnology or ecology, are applied to barotropic seiches through the analysis of water level data for Lake Geneva, Switzerland, and Lake Tahoe, USA. Using this technique, the autocorrelation of the measurements is estimated using the RDT and modal analysis can then be carried out on this time-domain signal to estimate periods of the dominant surface seiches and the corresponding damping ratios. The estimated periods show good agreement with experimental results obtained through conventional spectral techniques and consistent damping ratios are obtained for the dominant surface seiche of Lake Tahoe. The effect of input parameters is discussed, using data for the two lakes, alongside discussion of the application of RDT to the study of internal seiches and current barriers to its application. RDT has great potential for the analysis of both surface and internal seiches, offering a method through which accurate damping ratios of seiche oscillations may be obtained using readily available data without necessitating spectral analysis.