{"title":"Research on the methods for separating wind sea and swell from directional wave spectra in finite-depth waters","authors":"Zhenjun Zheng, Guohai Dong, Huawei Dong, Xiaozhou Ma, Mingfu Tang","doi":"10.1007/s10236-023-01592-6","DOIUrl":null,"url":null,"abstract":"<p>Ocean waves are generally a mix of wind sea and swell. Given the significant disparities in their impact on engineering, the separation of wind sea and swell is of great significance for marine research and engineering applications. This work focuses on studying the methods for separating wind sea and swell from directional wave spectra in finite-depth waters (i.e., the south coast of Sri Lanka). The error caused by deep-water dispersion relationship in the identification of wind sea using wave age (WA) criterion in finite-depth waters is revealed. The magnitude of error increases with decreasing water depth and higher wind speeds. Subsequently, the impact of WA thresholds on the partitioned results of wind sea and swell is examined, followed by a summary on the procedure determining an appropriate WA threshold. Finally, effort is devoted to studying the overshoot phenomenon (OP) criterion, which does not rely on wind data. Overall, the OP criterion performs consistently with the WA criterion. However, the generation and dissipation of OP require some time. Therefore, the OP criterion exhibits a lag in capturing the growing wind sea as well as the transition of the wind sea to a young swell. Misclassification of wind sea by the OP criterion further contaminates the bulk parameters of swell. Moreover, when the wind direction changes slowly, the delays of OP-based wind sea become negligible, leading to improved identification of wind sea and swell.</p>","PeriodicalId":19387,"journal":{"name":"Ocean Dynamics","volume":null,"pages":null},"PeriodicalIF":2.2000,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Ocean Dynamics","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1007/s10236-023-01592-6","RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"OCEANOGRAPHY","Score":null,"Total":0}
引用次数: 0
Abstract
Ocean waves are generally a mix of wind sea and swell. Given the significant disparities in their impact on engineering, the separation of wind sea and swell is of great significance for marine research and engineering applications. This work focuses on studying the methods for separating wind sea and swell from directional wave spectra in finite-depth waters (i.e., the south coast of Sri Lanka). The error caused by deep-water dispersion relationship in the identification of wind sea using wave age (WA) criterion in finite-depth waters is revealed. The magnitude of error increases with decreasing water depth and higher wind speeds. Subsequently, the impact of WA thresholds on the partitioned results of wind sea and swell is examined, followed by a summary on the procedure determining an appropriate WA threshold. Finally, effort is devoted to studying the overshoot phenomenon (OP) criterion, which does not rely on wind data. Overall, the OP criterion performs consistently with the WA criterion. However, the generation and dissipation of OP require some time. Therefore, the OP criterion exhibits a lag in capturing the growing wind sea as well as the transition of the wind sea to a young swell. Misclassification of wind sea by the OP criterion further contaminates the bulk parameters of swell. Moreover, when the wind direction changes slowly, the delays of OP-based wind sea become negligible, leading to improved identification of wind sea and swell.
海浪通常是风海和涌浪的混合体。由于风海和涌浪对工程的影响存在显著差异,因此风海和涌浪的分离对海洋研究和工程应用具有重要意义。这项工作的重点是研究从有限深度水域(即斯里兰卡南海岸)的定向波谱中分离风海和涌浪的方法。研究揭示了在有限深度水域使用波龄(WA)准则识别风海时,深水弥散关系造成的误差。误差幅度随水深减小和风速增大而增大。随后,研究了波龄阈值对风海和涌浪分区结果的影响,并总结了确定适当波龄阈值的程序。最后,对不依赖风力数据的过冲现象(OP)标准进行了研究。总体而言,OP 准则与 WA 准则的表现一致。不过,OP 的产生和消散需要一定的时间。因此,OP 准则在捕捉风海的增长以及风海向年轻涌浪的过渡方面表现出滞后性。OP 标准对风海的错误分类会进一步污染涌浪的体参数。此外,当风向变化缓慢时,基于 OP 的风海延迟变得可以忽略不计,从而改进了风海和涌浪的识别。
期刊介绍:
Ocean Dynamics is an international journal that aims to publish high-quality peer-reviewed articles in the following areas of research:
Theoretical oceanography (new theoretical concepts that further system understanding with a strong view to applicability for operational or monitoring purposes);
Computational oceanography (all aspects of ocean modeling and data analysis);
Observational oceanography (new techniques or systematic approaches in measuring oceanic variables, including all aspects of monitoring the state of the ocean);
Articles with an interdisciplinary character that encompass research in the fields of biological, chemical and physical oceanography are especially encouraged.