Ocean ModellingPub Date : 2025-01-25DOI: 10.1016/j.ocemod.2025.102502
Leo Peach , Nick Cartwright , Guilherme Viera da Silva , Darrell Strauss
{"title":"Enhancing downscaled ocean wave conditions with machine learning and wave spectra","authors":"Leo Peach , Nick Cartwright , Guilherme Viera da Silva , Darrell Strauss","doi":"10.1016/j.ocemod.2025.102502","DOIUrl":"10.1016/j.ocemod.2025.102502","url":null,"abstract":"<div><div>Machine Learning (ML) is becoming an increasingly popular and important tool for predicting ocean wave conditions. Here it is applied to downscale offshore conditions to a nearshore location utilising more detailed representations of the offshore wave field using 1D wave spectra. Our aim is to identify some of the sensitivities in input data when using machine learning to conduct downscaling (a common application) and present results from different approaches. The results demonstrate that downscaling wave conditions using ML can be enhanced using 1D wave spectra to improve performance. Here, we obtained a 27 % reduction in root mean squared error in significant wave height when compared to integrated parameter only machine learning approach with performance improved when using 1D wave spectra. Though we identified that the Long-Term Short-Term Memory approach applied here improved performance overall, it also appears there is not a one-size fits-all approach for all wave parameters. Careful feature selection (which features to include or exclude when training a model), feature engineering (such as feature encoding and sequence selection) and model configuration continue to be key factors in achieving accurate wave conditions.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102502"},"PeriodicalIF":3.1,"publicationDate":"2025-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean ModellingPub Date : 2025-01-22DOI: 10.1016/j.ocemod.2025.102501
Vassilios D. Vervatis , Pierre De Mey-Frémaux , John Karagiorgos , Bénédicte Lemieux-Dudon , Nadia K. Ayoub , Sarantis Sofianos
{"title":"Regional ocean model uncertainties using stochastic parameterizations and a global atmospheric ensemble","authors":"Vassilios D. Vervatis , Pierre De Mey-Frémaux , John Karagiorgos , Bénédicte Lemieux-Dudon , Nadia K. Ayoub , Sarantis Sofianos","doi":"10.1016/j.ocemod.2025.102501","DOIUrl":"10.1016/j.ocemod.2025.102501","url":null,"abstract":"<div><div>A Bay of Biscay model configuration is used as a test case to assess the data-based consistency of ensemble-based ocean model uncertainties of several types: [A] built-in stochastic parameterizations at regional ocean scales, [B] ocean model response to a global atmospheric model ensemble and [C] both A and B simultaneously. Ensembles of varying length were generated. In addition to a seasonal-range ensemble, three medium-range ensembles were carried out over successive overlapping segments permitting to compare consistency metrics for different lead times. The largest spread was obtained for the C case, although most of the model uncertainties were attributable to the stochastic ocean parameterizations in A. We addressed the question of which ensemble type and lead time was able to provide the most realistic model uncertainties given observations of SST, sea level, and Chlorophyll a, using a theoretical and diagnostic consistency analysis framework expanded from Vervatis et al. (2021a). In our results, consistency was satisfactory for the stochastic ensembles of types A and C, for the “aged” error cases (but only marginally with respect to the “young” error cases), and whenever physical and biogeochemical uncertainty processes were active in the region and could be detected by the observational networks, such as the onset of the spring shoaling of the thermocline and the phytoplankton abundance primary bloom. Sea level empirical consistency was improved when a wide range of low- to high-frequency errors were included in the signal of dynamic atmospheric process in the data and in the model inverse barometer. These findings provide additional insight that can help configure ensemble-based methods in academic studies and in operational ocean forecasting systems.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102501"},"PeriodicalIF":3.1,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean ModellingPub Date : 2025-01-09DOI: 10.1016/j.ocemod.2024.102494
Rodrigo Mogollón , Jorge Quispe , François Colas , Jorge Tam
{"title":"Role of atmospheric and oceanographic frequency variability on surface Marine Heatwaves in the Northern Humboldt Current System","authors":"Rodrigo Mogollón , Jorge Quispe , François Colas , Jorge Tam","doi":"10.1016/j.ocemod.2024.102494","DOIUrl":"10.1016/j.ocemod.2024.102494","url":null,"abstract":"<div><div>In this study, we investigated the role of atmospheric and oceanographic variability in shaping surface Marine Heatwaves (MHWs) in the Northern Humboldt Current System (NHCS) over the last two decades. Through a series of pluriannual hydrodynamic model simulations, we highlighted the importance of considering at least high-frequency atmospheric variability to accurately reproduce the observed MHW characteristics. On the contrary, when synoptic atmosphere variability is removed, the simulation results in fewer, longer, less frequent, less intense, and less severe MHWs. As a consequence, simulations forced with low-frequency data are only able to partially reproduce persistent MHWs. Additionally, using the heat balance analysis, it is shown that at the north, short-lived events are primarily driven by advective causes, while persistent events show an equal contribution between advection and heat fluxes. In the south, changes in heat fluxes are crucial in forming MHWs. During the dissipation phase of MHWs, cooling is dominated by advective processes, mainly coastal upwelling, in both coastal regions. Overall, these findings indicate a reduced dependence on high-frequency oceanic forcing and highlight the need to consider the atmospheric variability in regional downscaling of global climate model simulations to capture almost the full range of MHW events in the NHCS.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102494"},"PeriodicalIF":3.1,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean ModellingPub Date : 2025-01-08DOI: 10.1016/j.ocemod.2024.102496
Ajin Cho , Hajoon Song , Hyodae Seo , Rui Sun , Matthew R. Mazloff , Aneesh C. Subramanian , Bruce D. Cornuelle , Arthur J. Miller
{"title":"Dynamic and thermodynamic coupling between the atmosphere and ocean near the Kuroshio current and extension system","authors":"Ajin Cho , Hajoon Song , Hyodae Seo , Rui Sun , Matthew R. Mazloff , Aneesh C. Subramanian , Bruce D. Cornuelle , Arthur J. Miller","doi":"10.1016/j.ocemod.2024.102496","DOIUrl":"10.1016/j.ocemod.2024.102496","url":null,"abstract":"<div><div>Relative wind (RW; wind relative to surface currents) has been shown to play a crucial role in air-sea interactions, influencing both atmospheric and oceanic dynamics. While the RW effects through momentum flux are well-documented, those through turbulent heat fluxes remain unknown. In this study, we investigate two distinct surface current feedbacks – those associated with the momentum flux and turbulent heat fluxes – by modifying respective bulk formulations in the regional ocean-atmosphere coupled system, and analyze both immediate and seasonal changes in the boundary layers. Our results show that strong ocean currents in the Kuroshio Current and Extension significantly impact surface coupling, with responses generally contingent on the wind-current angle: an increase (decrease) in air-sea momentum and turbulent heat fluxes occurs when the low-level wind and surface currents are aligned (opposed). The instantaneous responses to surface currents include changes in low-level wind, surface current speed, and humidity, which are consistent with anticipated changes for a given wind-current angle based on the bulk formulations. While the wind-current angle is still an important factor, it does not adequately capture the seasonal responses. On the seasonal timescale, both surface current feedbacks can alter the path of the Kuroshio Extension and mesoscale activities, resulting in different background states that affect air-sea momentum and turbulent heat exchanges. Our results suggest that the energetic current system, such as the Kuroshio Current and Extension, can be significantly influenced by surface current coupling through both momentum and turbulent heat fluxes.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102496"},"PeriodicalIF":3.1,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean ModellingPub Date : 2025-01-07DOI: 10.1016/j.ocemod.2025.102497
E. Juanara, C.Y. Lam
{"title":"Machine Learning Approaches for Early Warning of Tsunami Induced by Volcano Flank Collapse and Implication for Future Risk Management: Case of Anak Krakatau","authors":"E. Juanara, C.Y. Lam","doi":"10.1016/j.ocemod.2025.102497","DOIUrl":"10.1016/j.ocemod.2025.102497","url":null,"abstract":"<div><div>A tsunami triggered by volcanic collapse is a low-probability but high-impact event. Unlike tsunamis triggered by earthquakes which the mechanism is well understood, volcanic tsunami events have complex trigger mechanisms and occur with little to no warning such as the event in December 2018 of the Anak Krakatau volcano tsunami, making it more difficult to detect and issue a warning. We adopted collapse tsunami machine learning (ML) approach model which does not require source information, to predict maximum tsunami amplitude on four coastal stations. Observations from six synthetic observation stations around Anak Krakatau volcano were used as input for collapse tsunami ML. The 320 collapse scenarios triggering tsunamis with various parameters and directions were generated to train model. To evaluate the accuracy and reliability of the tsunami simulations, we conducted a comparison between the simulated waveforms and those recorded at four coastal stations during the December 2018 event. The RMSE values between predicted and actual (via forward tsunami) of Random Forest model consistently provide the most accurate predictions ranging from 0.0586 to 0.1945 across three out of the four stations. We also applied deep learning algorithms, LSTM, and Complex LSTM to predict tsunami full waveform by using short-duration observation as input. Furthermore, we also pointed out the potential of risk management that can be explored and integrated from results of the maximum tsunami amplitude and arrival time predictions for support decision-making. We suggest that the ML approach could be a good alternative for volcanic tsunamis early warning purposes.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102497"},"PeriodicalIF":3.1,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On the speeding up and accuracy of the Second Order Moment (SOM) advection scheme using a mixed-precision method","authors":"Hideyuki Nakano, L. Shogo Urakawa, Kunihiro Aoki, Yuma Kawakami, Shoji Hirahara","doi":"10.1016/j.ocemod.2024.102495","DOIUrl":"10.1016/j.ocemod.2024.102495","url":null,"abstract":"<div><div>The ocean model is accelerated using the mixed-precision method for the second-order moment (SOM) advection scheme, which is highly accurate but computationally demanding. The execution time of the subroutine of the SOM scheme is successfully reduced by 43%, and since the SOM accounted for about 30% of the total time, the overall reduction in computation time is about 13%. A series of 300-year simulations showed that the mixed-precision method has sufficiently small negative impact on temperature (less than 0.02 °C), confirming that it can be used for climate simulations. When all the calculations are done in a simple single precision, an unacceptable difference in zonal mean temperature as a climate model of up to 0.4 °C in the deep ocean and 1 °C in the thermocline appears after the 300-year integration. We also conduct a sensitivity study using an idealized rectangular model, finding that consistency between the continuity equation and the tracer advection is necessary to guarantee accuracy in long-term integration, and it is shown that this consistency can be checked in a short time in a small rectangular domain as an salinity anomaly. In addition to the mixed-precision method, we have introduced two other methods for calculating the single-precision SOM algorithm. One is the Kahan method to compensate for the loss of information in the addition of some important variables represented in single precision, and the other is the conversion reduction method to compensate for the error due to data conversion between single and double precision at the entry and exit of subroutines. When both the methods are used simultaneously, the accuracy is comparable to mixed precision. We also evaluate them in an eddying OGCM and find that errors are difficult to evaluate because they are hidden by the inherent nonlinearity of the model at the stage when the nonlinearity develops.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102495"},"PeriodicalIF":3.1,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analysis of the impact of vertical variation and temporal frequency of the chlorophyll forcing field on modelled temperature in the Mediterranean Sea and potential implications for regional climate projections","authors":"Yutong Zhang , Florence Sevault , Romain Pennel , Melika Baklouti","doi":"10.1016/j.ocemod.2024.102490","DOIUrl":"10.1016/j.ocemod.2024.102490","url":null,"abstract":"<div><div>The urgency of climate change calls for the exploration of a variety of multi-forcing scenarios based on Shared Socio-economic Pathways. Ensuring the reliability of the climate projections is therefore an imperative prerequisite. In this paper, we examined the impact of the vertical variability and temporal frequency of the chlorophyll field used to force the NEMOMED12 ocean circulation model in the absence of a biogeochemical model on some key physical characteristics, mainly seawater temperature. Our analysis reveals that forcing by a chlorophyll field that is homogeneous in the vertical direction favours heat accumulation below the Deep Chlorophyll Maximum, leading to a positive temperature bias increasing with time. The extrapolation of the trend determined over the 11-year simulations leads to a bias in temperature as high as +1 °C after 100 years in the intermediate layer. Comparison with in situ data clearly shows that forcing the model with a realistically varying Chl field over the vertical allows the model to better represent temperature and avoid the presence of this bias. Additionally, we find that using the same chlorophyll field saved at different time frequencies, namely daily, monthly and monthly climatology, to force the NEMOMED12 model also creates temperature differences between simulations that increase with time, especially in the intermediate layer. The simulation forced by the daily chlorophyll is warmer in the surface layers than the two others, and we suggest that this is due to the asymmetric role of chlorophyll extremes on heat distribution. Finally, using a monthly chlorophyll climatology to force the NEMOMED12 ocean circulation model seems to be sufficient for physical modelling of the Mediterranean basin if the vertical variability of the Chl field is realistic.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102490"},"PeriodicalIF":3.1,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean ModellingPub Date : 2024-12-26DOI: 10.1016/j.ocemod.2024.102493
Xiaofeng Li , Haoyu Wang , Yi Yang , Xudong Zhang
{"title":"Deep learning-based solution for the KdV-family governing equations of ocean internal waves","authors":"Xiaofeng Li , Haoyu Wang , Yi Yang , Xudong Zhang","doi":"10.1016/j.ocemod.2024.102493","DOIUrl":"10.1016/j.ocemod.2024.102493","url":null,"abstract":"<div><div>Internal Solitary Waves (ISWs) are critical for ocean studies due to their large amplitude and long-travel capabilities. Conventionally, the Korteweg-de Vries (KdV) equations and their extensions are employed to simulate ISW properties, but traditional numerical methods lack flexibility and efficiency. This study introduces a universal, deep learning-based model that streamlines solving KdV-family equations. Within the framework of physics-informed neural networks, we implement an optimized Radial Basis Function (RBF) neural network and a new progressive expansion training strategy. This innovation minimizes error during training, leading to efficient convergence. Our model is tested on KdV and forced KdV equations, dimensional and non-dimensional equations using soliton, cnoidal, and dnoidal waveforms to simulate ISW propagation. The model results align with theoretical and numerical benchmarks, as demonstrated in a case study in the Sulu Sea. This paper does not concern ISW dynamics but uses the KdV equation as an example to showcase how to solve the partial differential equations with a new deep-learning method. The developed deep-learning model offers an efficient and accurate approach to solving KdV-family equations in oceanographic studies.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102493"},"PeriodicalIF":3.1,"publicationDate":"2024-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143148257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean ModellingPub Date : 2024-12-21DOI: 10.1016/j.ocemod.2024.102492
Caiyuan Cai , Bo Hong , Liangsheng Zhu , Hongzhou Xu , Ling Wang
{"title":"Impact of Stokes drift and washing-off on the pathways and accumulation of microplastics originating from a subtropical estuary","authors":"Caiyuan Cai , Bo Hong , Liangsheng Zhu , Hongzhou Xu , Ling Wang","doi":"10.1016/j.ocemod.2024.102492","DOIUrl":"10.1016/j.ocemod.2024.102492","url":null,"abstract":"<div><div>Highly urbanized river deltas are hotspots for microplastic (MP) pollution, yet research on the transport and accumulation of MPs from these estuaries remains limited. This study employed a Lagrangian particle-tracking model to elucidate the pathways and accumulation of MPs originating from the Pearl River Estuary over a three-year simulation. The results indicated that Stokes drift was the predominant factor influencing the southwestward transport of MPs. This movement led to their accumulation along the northeastern and southeastern coasts of Hainan Island, with a potential extension towards the Gulf of Thailand and Malaysia during the autumn and winter seasons. The combined effects of Stokes drift and washing-off processes enable some MPs entering the Beibu Gulf through Qiongzhou Strait. The washing-off processes disrupted the seasonal variations of MP pathways, altering the spatiotemporal distribution of MPs across different regions of the South China Sea. These findings could facilitate the local policymaking and environment protecting.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102492"},"PeriodicalIF":3.1,"publicationDate":"2024-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ocean ModellingPub Date : 2024-12-12DOI: 10.1016/j.ocemod.2024.102489
Yuhang Zhu , Shiqiu Peng
{"title":"A vortex-implanted initialization scheme for the mesoscale eddy prediction: Real simulation and hindcast","authors":"Yuhang Zhu , Shiqiu Peng","doi":"10.1016/j.ocemod.2024.102489","DOIUrl":"10.1016/j.ocemod.2024.102489","url":null,"abstract":"<div><div>This study aims to assess the effectiveness of applying the vortex-implanted initialization scheme for the mesoscale eddy prediction (VISTMEP) proposed by <span><span>Zhu et al. (2022)</span></span> in the real ocean. Both the Observational System Simulation Experiments (OSSEs) with real daily forcings and the real hindcast for the prediction of oceanic mesoscale eddies in the Northwest Pacific Ocean (NWPO) are conducted using an eddy-resolved numeric ocean model based on Regional Ocean Modeling System (ROMS) along with the three dimensional variational assimilation (3DVAR) module. The results show that, compared to the traditional initialization, VISTMEP can significantly reduce the biases in the prediction of characteristic quantities of mesoscale eddies (including the track, sea surface relative vorticity (SSRV), sea surface eddy kinetic energy (SSEKE), and scale) in both the OSSEs and the real hindcast, through optimizing the three dimensional (3D) structures of mesoscale eddies in both their initial states and evolutions. This study suggests that VISTMEP has a great potential application in operational service of the oceanic mesoscale eddy prediction.</div></div>","PeriodicalId":19457,"journal":{"name":"Ocean Modelling","volume":"194 ","pages":"Article 102489"},"PeriodicalIF":3.1,"publicationDate":"2024-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143147309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}