Ocean Modelling最新文献_第3页

The effect of tides on eddy viscosity via K-profile parameterization in the South China Sea near Luzon Strait

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-12-11 DOI: 10.1016/j.ocemod.2024.102488

Zhitao Yu , Yalin Fan , Alan Wallcraft , E. Joseph Metzger , Jay Shriver , Hemantha Wijesekera

The non-local K Profile Parameterization (KPP) is a one-dimensional parameterization of the vertical turbulence mixing in the water column. It is the main mixing scheme used in the HYbrid Coordinate Ocean Model (HYCOM). There are two distinct mixing regimes in KPP. In the ocean surface boundary layer (OSBL), the mixing is driven by surface forcing. In the ocean interior, vertical mixing is driven by resolved shear instability, internal wave background, and double diffusive mixing. In this research, two global HYCOM simulations conducted with and without tidal forcing are used to study how tides affect eddy viscosity in the South China Sea (SCS) near Luzon Strait in 2019. Our analysis reveals that tides play a crucial role in modifying eddy viscosity. Internal tides generated at Luzon Strait propagate into the SCS under tidal forcing conditions. They increase the vertical shear of the velocity and consequently enhance eddy viscosity in the ocean interior. Notably, the HYCOM simulation with tides demonstrates substantial eddy viscosity, reaching the order of 10⁻³ m²s⁻¹ at a depth of ∼2000 m at the Luzon Strait to the north of 20.3°N. The clear signature of spring-neap tidal cycle in the strong eddy viscosities in the ocean interior attribute their generation to internal tides. Due to the existence of the high-salinity North Pacific Tropical Water in the upper ocean of SCS (∼100 m), double diffusive mixing generated by salt fingering is shown to be more important than the background internal wave contribution at these depths. Tides also enhance the net downward surface heat flux and reduce the surface stress at Luzon Strait in both summer and winter of 2019. But tides mainly reduce (deepen) the OSBL depth at Luzon Strait in June (December) 2019 and lead mainly to a reduction (increase) of eddy viscosity in the OSBL in June (December) 2019.

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引用次数: 0

Long-duration storm surges due to 2023 successive UK storms Ciarán and Domingos: Generation, field surveys, and numerical modelling

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-12-10 DOI: 10.1016/j.ocemod.2024.102487

Mohammad Heidarzadeh , Jadranka Šepić , Takumu Iwamoto

We model the long-duration storm surges generated by October–November 2023 storm chain in the English Channel employing a hybrid method including numerical modelling, field surveys and analysis of oceanic and atmospheric data. The event consisted of three successive storms: a weaker unnamed storm (27–30 October), Storm Ciarán (2–3 November with minimum pressure 948 hPa) and Storm Domingos (4–5 November with minimum pressure 958 hPa). The average surge duration produced by this storm chain was 10.5 days. The average maximum air pressure drop was 42 hPa during Ciarán and 23 hPa during Domingos. These pressure drops, combined with onshore wind stresses, led to average maximum storm surge amplitudes of 92 cm for Ciarán and 74 cm for Domingos. We accurately modelled storm surges using a three-level nested grid system and validated the results with tide gauge data. Sensitivity analysis showed a spatially-dependant impacts from tides and waves on maximum surge amplitudes. To correlate our modelling and data analysis with actual conditions on the ground, field surveys were conducted where we measured a runup heights of 4.1 m in Chesil Beach and 2.1 m in West Bay. These values were successfully reproduced by two independent empirical runup models enabling adaption of suitable models for storm hazard mitigation and resilience. A meteotsunami with an amplitude of 17–23 cm and a period of 11–40 min was identified during Ciarán. The innovative hybrid framework developed in this study is recommended for building robust systems for storm warnings and coastal resilience.

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引用次数: 0

Assessing the effects of climate change on the Gulf of Mexico wave climate using the COWCLIP framework and the PRECIS regional climate model

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-12-08 DOI: 10.1016/j.ocemod.2024.102486

Christian M. Appendini , Pablo Ruiz-Salcines , Reza Marsooli , Ruth Cerezo-Mota

The present study utilized downscaled wind projections from the PRECIS regional climate model to project and assess changes in wind-generated waves in the Gulf of Mexico under a warmer climate. The methodology entailed simulating waves using a high-resolution and validated third-generation wave model. The wave model was first forced with historical winds from the Climate Forecast Systems Reanalysis (CFSR) to evaluate the accuracy of the model for studying wave climate. The wave model was then forced by downscaled HadGEM winds from PRECIS (HadRM3P) to quantify wave climate change from the historical period (1980–2005) to a future period (2030–2054) under a high emission scenario. Wave climate patterns were analyzed using the framework developed by the Coordinated Ocean Wave Climate Project (COWCLIP), which ensures consistency across different studies, allowing researchers to compare results from various regions and models more effectively. The results provide a comprehensive assessment of the wave climate in the Gulf of Mexico, suggesting more intense wave conditions in a warmer climate. The quantified effects of global warming on future wave conditions can inform key economic sectors in the region, such as oil and gas production, shipping, tourism, and fisheries.

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引用次数: 0

Modelling of hurricane Dorian via the implementation of Wave Boundary Layer Model (WBLM) within the OpenIFS

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-12-07 DOI: 10.1016/j.ocemod.2024.102469

Nefeli Makrygianni , Shunqi Pan , Michaela Bray , Jean R. Bidlot

For over three decades numerous studies have tried to understand the processes and impacts of air–sea interactions on the atmosphere and oceans, particularly in predicting winds and waves under tropical cyclone conditions. Literature has highlighted the critical role of momentum transfer, with various parameterisations proposed for the momentum fluxes, through the drag coefficient (

C_{d}

) and the roughness (

z_{0}

). However, accurate predictions still remain a significant challenge. Recently, Du et al. (2017,2019) proposed a comprehensive calculation of the source input function using a Wave Boundary Layer Model (WBLM). However, their study used a standalone model rather than a coupled system. Given the established significance of two-way wind-wave systems (Janssen, 1991), this study implements the WBLM within a coupled model (OpenIFS), to evaluate its impact and discuss the potential and limitations of the method. Numerical simulations were conducted using the WBLM scheme for a selected tropical cyclone, with results compared against in-situ buoy measurements and satellite altimeter data. Furthermore, the new approach’s results were compared with outputs using the default, well-established source input function of OpenIFS (Janssen et al., 1989; Janssen, 1991) to further assess its effectiveness. The findings suggest that the WBLM tends to reduce the commonly overestimated drag and Charnock coefficients. However, comparisons with in-situ observations indicate that the new approach requires substantial refinements to improve wind and wave predictions, since there are cases that the WBLM scheme under-performs the default scheme. This discrepancy may be attributed to the calculation of high-frequency impacts on momentum exchanges.

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引用次数: 0

Model-based assessment of sustainable adaptation options for an industrialised meso‑tidal estuary

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-11-28 DOI: 10.1016/j.ocemod.2024.102467

Johannes Pein , Joanna Staneva , Johanna Biederbick , Corinna Schrum

Human-shaped estuaries play a vital role in supporting a range of economic, ecological and social functions. Such cultural landscapes often require enormous services, which may be provided at the expense of the ecological status and the ability to provide ecosystem services. This is exemplified by the estuaries of the German North Sea coast, of which the Elbe estuary is the most prominent and stands out as the largest and most consistently developed. The port of Hamburg, which is the primary economic driver in the region, has shaped the morphology of the surrounding water body. This has resulted in a number of hydrodynamic effects and sedimentological and ecological consequences, which have been well documented and subject to extensive debate. Despite this understanding, however, there is a tendency to propose solutions that are limited to the smallest local scales and are unable to mitigate the consequences of human interventions that have taken place or continue to take place at the estuarine and catchment scales. The lack of illustrative and quantitative scenario simulations and holistic assessments also hinders the ability to implement ambitious adaptation measures. To step forward, this study presents a model-based assessment including scenario simulations of four prototypical adaptation measures that are potentially capable of mitigating the problems of high turbidity, sedimentation and oxygen minimum without compromising coastal protection. The experimental design comprises a two-month morphodynamic simulation for each adaptation scenario and a one-year simulation of coupled hydrodynamics and ecology. The model simulations demonstrate that the proposed measures have the potential to reduce the siltation of the upper estuary, thereby reducing the need for extensive and costly maintenance dredging. Furthermore, the simulated measures also reduce the tidal range in the densely populated upper estuary, albeit to varying degrees. This also applies to mitigating the consequences of eutrophication, such as the oxygen content in the navigation channel. These differences, as well as the differing scale and effort associated with the four measures, form the basis of a final comparative evaluation based on universal sustainability criteria.

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引用次数: 0

Wave climate projections off coastal French Guiana based on high-resolution modelling over the Atlantic Ocean

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-11-28 DOI: 10.1016/j.ocemod.2024.102468

Maurizio D'Anna , Léopold Vedie , Ali Belmadani , Déborah Idier , Remi Thiéblemont , Philippe Palany , François Longueville

Global warming is altering the atmosphere and ocean dynamics worldwide, including patterns in the generation and propagation of ocean waves, which are important drivers of coastal evolution, flood risk, and renewable energy. In French Guiana (northern South America), where most of the population is concentrated in coastal areas, understanding future wave climate change is critical for regional development, planning and adaptation purposes. The most energetic waves typically occur in boreal winter, in the form of long-distance swell originating from the mid-latitude North Atlantic Ocean. However, existing high-resolution wave climate projections that cover the French Guiana region focus on the hurricane season only (summer-fall). In this study, we used a state-of-the-art basin-scale spectral wave model and wind fields from a high-resolution atmospheric global climate model to simulate present and future winter (November to April) wave climate offshore of French Guiana. The model performance was evaluated against wave data from ERA5 reanalysis, satellite altimetry and coastal buoys between 1984 and 2013. For the future greenhouse gas emission scenario (Representative Concentration Pathway) RCP-8.5, we found a statistically significant overall projected decrease (∼5 %) in wintertime average significant wave height and mean wave period, with a ∼1° clockwise rotation of mean wave direction. The results suggest that these decreasing trends are primarily driven by changes in large-scale patterns across the Atlantic that counteract an expected increase in local wind speed. We discuss the implications of such projections for mud-bank dynamics along coastal French Guiana, although further local studies are required to address future coastal evolution and hazards. Finally, we identify a need for more in situ wave data near French Guiana to improve quantitative assessments of model performance and allow a correction of possible model biases.

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引用次数: 0

On long-crested ocean rogue waves originating from localized amplitude and frequency modulations 由局部振幅和频率调制产生的长峰海洋异常波

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-11-22 DOI: 10.1016/j.ocemod.2024.102464

Yuchen He , Amin Chabchoub

Rogue waves, which form on the ocean’s surface, can cause significant damage to marine installations and pose a serious threat to ship safety. Understanding the physical mechanisms behind extreme wave focusing is crucial for predicting their formation and mitigating their impact. Two intensively discussed wave amplification frameworks are the linear and nonlinear focusing mechanisms. These are also known as superposition principle and modulation instability, respectively. We report an experimental study investigating the formation mechanisms in a unidirectional representative JONSWAP-type sea state and show that the nonlinear focusing principle can be sub-categorized into either a localized amplitude or a so far less-studied phase-related frequency modulation, or both being at play. The frequency modulation-type mechanism occurs at a lower probability, as suggested from the distribution of more than 200 recorded extreme events, however, it cannot be underrated or disregarded.

在海洋表面形成的巨浪会对海洋设施造成重大破坏，并对船舶安全构成严重威胁。了解极端波聚焦背后的物理机制对于预测其形成和减轻其影响至关重要。两个主要讨论的波放大框架是线性聚焦机制和非线性聚焦机制。这些也分别被称为叠加原理和调制不稳定性。我们报告了一项实验研究，调查了单向代表性jonswap型海况的形成机制，并表明非线性聚焦原理可以细分为局部幅度或迄今为止研究较少的与相位相关的频率调制，或者两者都在起作用。从200多个记录的极端事件的分布来看，调频型机制发生的概率较低，但不能低估或忽视它。

引用次数: 0

RLM: Rearranged level-set method - An efficient approach for calculating temporally continuous Lagrangian Residual Velocities

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-11-20 DOI: 10.1016/j.ocemod.2024.102466

Guangliang Liu , Fei Ji , Zhe Liu , Chongxin Luo

The Lagrangian Residual Velocity (LRV) is the subtidal residual current extracted from oscillating tidal water motions to depict the coastal circulation. Since the LRVs are sensitive to the initial time, the most widely used particle tracking method (PTM) must be used repeatedly to obtain temporally continuous LRVs. A new method, the rearranged level-set method (RLM), is introduced to efficiently obtain temporally continuous LRVs. Compared with the analytical solution of LRVs in a long narrow bay, both the RLM-LRVs and the PTM-LRVs can reproduce multiple gyre structures. However, the region of directional bias above 60° in the RLM-LRVs is limited to the narrow gyre conjunction region, while that in the PTM-LRVs extends up to half the bay width and 10% of the bay length. In particular, the RLM can produce temporally continuous LRVs with much higher computational efficiency than the PTM. The RLM also performs well in complex coastal sea areas, such as a cape with a staircase topography, rectangular coastline, and Jiaozhou Bay (JZB), a realistic small waterbody with complex coastline and topography. The RLM-derived temporally continuous LRVs can illustrate the evolution of the two small gyres perturbed by the staircase topography in the cape, and the two gyre cores embedded in the large dominant counterclockwise gyre move separately along the deep channels in the JZB while the PTM cannot. In conclusion, the RLM is a fast and accurate method for calculating temporally continuous LRVs.

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引用次数: 0

Upgrade of the Chilean Wave Atlas database 升级智利波浪图数据库

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-11-19 DOI: 10.1016/j.ocemod.2024.102456

Sebastian Omar Correa Araya , Catalina Aguirre , Diego Becerra , Mauricio Molina , Pablo Vilchez , Sergio Bahamóndez

The Chilean Wave Atlas (AOC1), a reliable hindcast developed in 2017 for the academic and engineering community, diminished its usefulness due to the obsolescence of wind data provided by ERA-Interim reanalysis. This study presents the calibration and validation of a new wave hindcast forced using hourly winds data from ERA5 reanalysis. A total of 24 simulations were conducted: 15 using the semi-empirical ST4 parameterization and 9 using the observed-based ST6 parameterization, both implemented in WaveWatch III. Model results were compared with in-situ wave data from buoys along the Chilean coast. Generally, the ST4 physics package demonstrated superior performance with minimal variability in error statistical parameters between simulations. However, the observed-based ST6 parameterization produced the best results for simulating wave direction. By defining a multi-criteria performance score, the optimal model configuration was selected, and a new hindcast was generated for the period between 1979 and 2022. This hindcast includes hourly fields of significant wave height, mean and peak wave period, and mean and peak wave direction for the Pacific Ocean, as well as 72 locations with directional spectra. The upgraded Chilean Wave Atlas (AOC3) significantly improves the performance of AOC1 when compared with satellite-derived wave heights along the Chilean coast. Furthermore, the AOC3 data show good performance compared to other freely available hindcasts.

智利波浪图集（AOC1）是 2017 年为学术和工程界开发的可靠后报，但由于 ERA-Interim 再分析提供的风数据过时，其实用性大打折扣。本研究利用ERA5再分析的每小时风数据，对新的波浪后报进行了校准和验证。共进行了 24 次模拟：15 次使用半经验 ST4 参数化，9 次使用基于观测的 ST6 参数化，这两种参数化均在 WaveWatch III 中实现。模拟结果与智利沿岸浮标的现场波浪数据进行了比较。总体而言，ST4 物理软件包性能优越，模拟结果之间的误差统计参数变化极小。不过，基于观测的 ST6 参数化在模拟波浪方向方面取得了最佳结果。通过多标准性能评分，选出了最佳模型配置，并生成了 1979 年至 2022 年期间的新后报。后报包括太平洋每小时的显著波高、平均和峰值波周期、平均和峰值波方向，以及 72 个地点的方向谱。升级后的智利波浪图集（AOC3）与智利沿岸的卫星波高相比，大大提高了 AOC1 的性能。此外，与其他免费提供的后预报相比，AOC3 数据显示出良好的性能。

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引用次数: 0

Advancing sea level anomaly modeling in the black sea with LSTM Auto-Encoders: A novel approach 利用 LSTM 自动编码器推进黑海海平面异常建模：一种新方法

IF 3.1 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Ocean Modelling

Pub Date : 2024-11-16 DOI: 10.1016/j.ocemod.2024.102463

A. Yavuzdoğan , E. Tanir Kayıkçı

Rising sea levels pose significant risks to coastal communities and ecosystems. Accurate modeling of sea level changes is crucial for effective environmental management and disaster mitigation. Machine learning methods are emerging as an important asset in improving sea level predictions and understanding the impacts of climate change. Especially, Long Short-Term Memory (LSTM) models have emerged as a powerful tool for sea level anomaly modeling, but there is an increasing need for more advanced models in this area. This study enhances existing methodologies by introducing a novel approach using an LSTM Auto-Encoder model, designed to compress input data into a lower-dimensional latent space before reconstructing it, thereby capturing complex temporal dependencies and anomalies effectively. We compared LSTM Auto-Encoder model performance with that of a Stacked LSTM network, which learns complex temporal patterns through multiple layers, and a traditional damped-persistence statistical model. Our results demonstrate that the LSTM Auto-Encoder model not only outperformed these models in predicting sea level anomalies across various lead times but also exhibited superior generalization capabilities across both satellite altimeter and in-situ data. These findings highlight the potential of the LSTM Auto-Encoder model as a powerful tool in coastal management and climate change studies, underscoring the critical role of advanced machine learning techniques in enhancing our predictive abilities and informing disaster preparedness strategies.

海平面上升对沿海社区和生态系统构成重大风险。海平面变化的精确建模对于有效的环境管理和减灾至关重要。机器学习方法正在成为改进海平面预测和了解气候变化影响的重要资产。特别是长短期记忆（LSTM）模型已成为海平面异常建模的有力工具，但该领域对更先进模型的需求与日俱增。本研究采用 LSTM 自动编码器模型改进了现有方法，该模型旨在将输入数据压缩到较低维度的潜在空间，然后再进行重建，从而有效捕捉复杂的时间依赖关系和异常现象。我们将 LSTM 自动编码器模型的性能与通过多层学习复杂时间模式的堆叠 LSTM 网络和传统的阻尼-持久统计模型进行了比较。我们的研究结果表明，LSTM 自动编码器模型不仅在预测不同提前期的海平面异常方面优于这些模型，而且在预测卫星高度计数据和现场数据方面也表现出卓越的泛化能力。这些发现凸显了 LSTM Auto-Encoder 模型作为沿海管理和气候变化研究的有力工具的潜力，强调了先进的机器学习技术在提高我们的预测能力和为备灾战略提供信息方面的关键作用。

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引用次数: 0