Ocean Environment Research Articles

An End-to-End Ocean Environmental Noise Anomaly Detection Framework Combining Time–Frequency Information and Expert Gating

The detection and optimization of ocean environmental noise anomalies play a crucial role in enhancing the safety of marine engineering applications and ecological protection. Current anomaly detection methods for ocean environmental noise often suffer from issues of accuracy and robustness. To address these challenges, this paper first proposes an end-to-end framework that combines time–frequency information and expert gating, significantly improving the precision of noise sequence generation. Secondly, a Gamma distribution-based residual analysis method for anomaly detection is designed, enhancing the robustness of anomaly detection. Finally, an anomaly optimization module is developed to improve data quality, enabling efficient noise anomaly detection and optimization. Our experimental results demonstrate that the proposed model significantly outperforms traditional models in multi-frequency noise prediction, with strong robustness in anomaly detection and high generalization performance. The proposed framework offers a novel approach for analyzing the causes of noise anomalies and optimizing models. Additionally, the research outcomes provide efficient technical support for deep-sea exploration, equipment optimization, and environmental protection.

Accelerating CO2 Outgassing in the Equatorial Pacific from Satellite Remote Sensing

The equatorial Pacific serves as the world’s largest oceanic source of CO2. The contrasting ocean environment in the eastern (i.e., upwelling) and western (i.e., warm pool) regions makes it difficult to fully characterize its CO2 dynamics with limited in situ observations. In this study, we addressed this challenge using monthly surface partial pressure of CO2 (pCO2sw) and air-sea CO2 fluxes (FCO2) data products reconstructed from satellite and reanalysis data at a spatial resolution of 1° × 1° in the period of 1982–2021. We found that during the very strong El Niño events (1997/1998, 2015/2016), both pCO2sw and FCO2 showed a significant decrease of 41–58 μatm and 0.5–0.8 mol·m−2·yr−1 in the eastern equatorial Pacific, yet they remained at normal levels in the western equatorial Pacific. In contrast, during the very strong La Niña events (1999/2000, 2007/2008, and 2010/2011), both pCO2sw and FCO2 showed a strong increase of 40–48 μatm and 1.0–1.4 mol·m−2·yr−1 in the western equatorial Pacific, yet with little change in the eastern equatorial Pacific. In the past 40 years, pCO2sw in the eastern equatorial Pacific was increasing at a higher rate (2.32–2.51 μatm·yr−1) than that in the western equatorial Pacific (1.75 μatm·yr−1), resulting in an accelerating CO2 outgassing (at a rate of 0.03 mol·m−2·yr−2) in the eastern equatorial Pacific. We comprehensively analyzed the potential effects of different factors, such as sea surface temperature, sea surface wind speed, and ΔpCO2 in driving CO2 fluxes in the equatorial Pacific, and found that ΔpCO2 had the highest correlation (R ≥ 0.80, at p ≤ 0.05), highlighting the importance of accurate estimates of pCO2sw from satellites. Further studies are needed to constrain the retrieval accuracy of pCO2sw in the equatorial Pacific from satellite remote sensing.

Long-Term Evaluation of GCOM-C/SGLI Reflectance and Water Quality Products: Variability Among JAXA G-Portal and JASMES

The Global Change Observation Mission-Climate (GCOM-C) satellite, launched in December 2017, is equipped with the Second-generation Global Imager (SGLI) sensor, featuring a moderate spatial resolution of 250 m and 19 spectral bands, including the unique 380 nm band. After six years in orbit, a comprehensive evaluation of SGLI products and their temporal consistency is needed. Remote sensing reflectance (Rrs) is the primary product for monitoring water quality, forming the basis for deriving key oceanic constituents such as chlorophyll-a (Chla) and total suspended matter (TSM). The Japan Aerospace Exploration Agency (JAXA) provides Rrs products through two platforms, G-Portal and JASMES, each employing different atmospheric correction methodologies and assumptions. This study aims to evaluate the SGLI full-resolution Rrs products from G-Portal and JASMES at regional scales (Japan and East Asia) and assess G-Portal Rrs products globally between January 2018 and December 2023. The evaluation employs in situ matchups from NASA’s Aerosol Robotic Network-Ocean Color (AERONET-OC) and cruise measurements. We also assess the retrieval accuracy of two water quality indices, Chla and TSM. The AERONET-OC data analysis reveals that JASMES systematically underestimates Rrs values at shorter wavelengths, particularly at 412 nm. While the Rrs accuracy at 412 nm is relatively low, G-Portal’s Rrs products perform better than JASMES at shorter wavelengths, showing lower errors and stronger correlations with AERONET-OC data. Both G-Portal and JASMES show lower agreement with AERONET-OC and cruise datasets at shorter wavelengths but demonstrate improved agreement at longer wavelengths (530 nm, 565 nm, and 670 nm). JASMES generates approximately 12% more matchup data points than G-Portal, likely due to G-Portal’s stricter atmospheric correction thresholds that exclude pixels with high reflectance. In situ measurements indicate that G-Portal provides better overall agreement, particularly at lower Rrs magnitudes and Chla concentrations below 5 mg/m3. This evaluation underscores the complexities and challenges of atmospheric correction, particularly in optically complex coastal waters (Case 2 waters), which may require tailored atmospheric correction methods different from the standard approach. The assessment of temporal consistency and seasonal variations in Rrs data shows that both platforms effectively capture interannual trends and maintain temporal stability, particularly from the 490 nm band onward, underscoring the potential of SGLI data for long-term monitoring of coastal and oceanic environments.

Reproductive strategies in loggerhead sea turtle Caretta caretta: polyandry and polygyny in a Southwest Atlantic rookery.

Sea turtles are highly migratory and predominantly inhabit oceanic environments, which poses significant challenges to the study of their life cycles. Research has traditionally focused on nesting females, utilizing nest counts and mark-recapture methods, while male behavior remains understudied. To address this gap, previous studies have analyzed the genotypes of females and hatchlings to indirectly infer male genotypes and evaluate the extent of multiple paternity within populations. Our research aimed to investigate the presence of multiple paternity in loggerhead turtle (Caretta caretta) nests for the first time in Brazil. We analyzed 534 hatchlings from 43 nests associated with 42 females during the 2017/18 to 2019/20 nesting seasons, using four highly polymorphic, species-specific microsatellite markers (nDNA). Parentage tests were conducted to reconstruct paternal genotypes and determine the rates of multiple paternity within clutches. Our results revealed that 72.09% of clutches were sired by multiple males, with contributions ranging from one to six males per clutch. Additionally, seven out of 88 males (7.95%) were found to have sired clutches from multiple females, with some males contributing to more than one clutch within and across breeding seasons. The breeding sex ratio (BSR) was calculated to be 2.09 males per female. While multiple paternity is a common phenomenon among sea turtles, this study is the first to document polyandry in loggerheads in Brazil and the first to provide evidence of polygyny in this species globally. This research establishes a crucial database for future studies in Brazil, with a focus on the BSR of the Southwest Atlantic subpopulation, offering essential insights for developing effective management strategies for this vulnerable population.

Proteogenomics for Non-model Ocean-Derived Fungi.

Most biological and biomedical experiments are designed and studied using the most common model organisms (MOs) like humans, mice, Escherichia coli, Saccharomyces cerevisiae, Neurospora crassa, worms, fruit flies, zebrafish, and Arabidopsis thaliana. These model organisms have been extensively studied and have a well-established set of genetic, physiological, and other tools available for research. In contrast, non-model organisms (NMOs) are those that are not traditionally used in scientific research and do not have a well-established set of genetic or other biological tools available for their study. The majority of MOs are associated with land habitats but rarely with ocean environments. The ocean forms the largest portion of our planet, yet ocean-derived organisms are the least explored, and these organisms are primarily NMOs. However, these are thrilling living entities, such as ocean-derived fungi (ODF). These ODFs are a diverse group of fungi that live in different ocean sectors, including the ocean, estuaries, and coastal ecosystems. These fungi are found to colonize and adapt to different substrates. They are important decomposers in marine ecosystems, breaking down dead organic matter and recycling nutrients. ODFs have adapted to survive in the unique and challenging conditions of the ocean environment, including high salt concentrations, low nutrient availability, and exposure to waves and currents. ODFs are potent producers of natural compounds with pharmaceutical and industrial applications, such as antibiotics, anticancer agents, antivirals, and enzymes for industrial processes. ODFs are an exciting group of fungi; however, these are the least studied because of the nonavailability of MOs from this group. Hence, there is a massive scope of expanding our current knowledge about ODFs, their genetic traits, potential future drug-producing capabilities, and lifestyle traits.With the advent of next-generation DNA sequencing, there is huge potential for the characterization of the genetic material of ODF as NMOs. Parallel proteomic methods also pose huge potential. A marriage of NGS and proteomic methods generates a new avenue called proteogenomics, which focuses on better annotation of existing genomic data. Both methods are getting cheaper and accessible to the research community for studying the proteogenomics of NMOs. Herein, the proteogenomic protocol development and data analyses are illustrated for the ocean-derived fungus Scopulariopsis brevicaulis.

Using Digital Twins of the Ocean to Build Capacity in the Wider Caribbean Region

An emerging technology for building capacity to make decisions in the ocean space is the development of Digital Twins of the Ocean (DTOs). A DTO is a virtual replication of the ocean environment, including its properties, behaviors, and processes (https://www.​mercator-​ocean.eu/​en/​digital-​twin-ocean/). These digital replicas are created using a combination of real-time data collected from satellites and thousands of sensors deployed around the world, as well as outputs of advanced models and computer simulations.

The Coastal Ocean Environment Summer School In Nigeria and Ghana: The Value of Long-Term, Sustained Capacity Sharing

The Coastal Ocean Environment Summer School In Nigeria and Ghana (COESSING; https://coessing.org) has been run for one week every year since 2015. The school, an endorsed project of the United Nations Decade of Ocean Science for Sustainable Development (2021–2030), has provided a platform for approximately 1,000 scientists from Africa, the United States, and Europe to exchange scientific knowledge, to network, to learn, and to collaborate. Our interdisciplinary, multicultural, and multi-institutional approach offers a model for knowledge exchange across the globe and across different educational levels.

MPT: a large-scale multiphytoplankton tracking benchmark

Phytoplankton are crucial for aquatic ecosystems and provide valuable insights into ocean environments and changes in ecosystems. Traditional phytoplankton monitoring methods are often complex and lack timely analysis capabilities. Thus, deep learning algorithms offer a promising approach for automated phytoplankton monitoring. However, the lack of large-scale, high-quality training datasets presents a major bottleneck in advancing phytoplankton tracking. Herein, we propose a challenging benchmark dataset called multiple phytoplankton tracking (MPT), which covers diverse background information and motion variations during observation. The dataset includes 27 phytoplankton and zooplankton species, 14 different backgrounds to simulate diverse and complex underwater environments, and 140 videos. To enable accurate real-time phytoplankton observation, we introduce the deviation-corrected multiscale feature fusion tracker (DSFT), a multiobject tracking method designed to overcome key issues such as focus shifts during tracking and the loss of critical information on small targets when computing frame-to-frame similarity. To enhance efficiency, we incorporate an additional feature extractor that predicts residuals from the output of the standard feature extractor; this enables multiscale frame-to-frame similarity comparisons based on features from different extractor layers. Extensive experiments conducted on the MPT dataset validated its effectiveness and demonstrated the superior performance of the DSFT method in tracking phytoplankton, providing an effective solution for phytoplankton monitoring.

Metabolites reflect variability introduced by mesoscale eddies in the North Pacific Subtropical Gyre

Mesoscale eddies significantly alter open ocean environments such as those found in the subtropical gyres that cover a large fraction of the global ocean. Previous studies have explored eddy effects on biogeochemistry and microbial community composition but not on the molecular composition of particulate organic matter. This study reports the absolute concentration of 67 metabolites and relative abundances for 640 molecular features, measured using liquid chromatography-mass spectrometry (LC-MS) following both targeted and untargeted approaches. This approach allowed us to better understand how mesoscale eddies impact the metabolome of the North Pacific Subtropical Gyre during two cruises in 2017 and 2018. We find that many metabolites track biomass trends, but metabolites like isethionic acid, homarine, and trigonelline linked to eukaryotic phytoplankton were enriched at the deep chlorophyll maximum of the cyclonic features, while degradation products such as arsenobetaine were enriched in anticyclones. In every analysis, the metabolites with the strongest responses were identified using LC-MS through untargeted metabolomics approaches, highlighting that the molecules most sensitive to environmental perturbation were not among the previously characterized metabolome. By analyzing depth variability (accounting for 20-40% of metabolomic variability across ~150 meters) and the vertical displacement of isopycnal surfaces (explaining 10-20% of variability across a sea level anomaly range of 40 centimeters and a spatial distance of 300 kilometers), this analysis constrains the importance of mesoscale eddies in shaping the chemical composition of particulate matter in the largest biomes on the planet.

A High-Resolution Microscopy System for Biological Studies of Cold-Adapted Species Under Physiological Conditions.

The Antarctic seabed harbors significant biodiversity, and almost 90% of oceanic environments are permanently below 5 °C (i.e., deep sea and polar regions). However, organisms whose entire lifecycle occurs around 0 °C are understudied, leaving this large and diverse proportion of the global biome poorly understood. To address this question at the cellular level, tools are required for high-resolution imaging of biological systems under physiological conditions. This poses severe technical challenges. High-resolution imaging objectives require short working distances and immersion media, causing rapid heat transfer from the microscope to the sample. This affects the viability of live specimens and the interpretability of results. Here, we present a method for high-fidelity imaging of live biological samples at temperatures of around, or below, 0 °C. It relies on hardware additions to traditional microscopy, namely as a cooling collar, 10% ethanol as an immersion medium, and nitrogen flow to reduce condensation It can be straightforwardly implemented on different microscopy modalities, including super-resolution imaging. The method is demonstrated in live cell cultures derived from Antarctic fish and highlights the need to maintain physiological conditions for these fragile samples. Future applications include evolutionary biology, biophysics and biotechnology.

Why Does the Biosphere Interact with Earth's Climate, and How Do the Two-Way Interactions Work?

With the use of matter (carbon dioxide, nutrients, and water) and solar energy, phytoplankton produce oxygen and carbohydrates, which are transported to predators through the oceanic food web hierarchy. From the viewpoint of irreversible processes of non-equilibrium thermodynamics, oceanic photosynthesis gives a mechanistic picture of living things characterized by double sets of self-organizations supported by flows of energy and entropy discarded into the ocean environment. This produces biological, ocean circulation, and climate interactions.

Fine-scale residency and temperature-driven habitat selection in a migratory shark species

AbstractMany marine species exhibit complex and diverse movements that vary across spatial and temporal scales. These movements must be accounted for when designing effective management and conservation efforts. While environmental cues such as temperature and salinity have been shown to influence the movements of mobile species, it is increasingly documented that social factors can also influence space use and population behaviour. Understanding how various factors influence movement enhances our ability to predict the space use of highly dynamic ocean species. Spurdog (Squalus acanthias), known for their tendency to aggregate and use of both coastal and oceanic environments, are an ideal model species for studying drivers of movement. To investigate movement and habitat selection in spurdog, we conducted an acoustic telemetry study from June 2016 to July 2017, tagging 51 spurdog in a partially enclosed fjordic sea loch on the west coast of Scotland. The thermal profile of Loch Etive was recorded to complement the movement data. Our study revealed temperature as a pivotal driver of movement and habitat selection in spurdog, with the unique thermal environment of the fjord enabling year-round residency at a previously undocumented spatial scale, suggesting that such habitats may be especially important for mobile marine species. This study demonstrates the importance of understanding environmental influences on space use and movement to develop effective, climate-resilient management strategies for spurdog and other mobile marine species.

Reservoir Regulation Changed Terrestrial Particulate Organic Carbon Transport and Burial Processes off the Yellow River Mouth

AbstractThe dynamic behavior of particulate organic carbon (POC) is crucial for understanding biogeochemical carbon cycling in coastal and oceanic environments. However, intense watershed human activities have significantly altered the POC transport and burial in the estuary‐coast continuum. Here, we developed a novel parameterization scheme that incorporates grain‐size constraints to investigate the dispersal and accumulation processes of POC off the Yellow River mouth during the water‐sediment regulation scheme (WSRS) using a three‐dimensional hydrodynamic model (FVCOM). The result shows that the model successfully captures the offshore transport and hydrodynamic sorting of POC, which leads to a progressive increase in POC content with offshore dispersion and significant variations in POC and sediment deposition across different isobaths. Rapid fluctuations in river discharge and sediment composition during WSRS stages result in noticeable differences in sedimentation patterns for sediment and POC. At the Water‐regulation stage, distinct differences are observed in the distribution of riverine POC and sediment across various isobaths. In contrast, during the Sediment‐regulation stage, these differences are significantly reduced due to the finer riverine sediment. Compared to the sediment‐regulation, the Water‐regulation plays a crucial role in enhancing the effective burial of POC. Coarse‐grained sediment can form an armored layer that protects OC from disturbance. Additionally, increased runoff during this stage promotes the offshore transport of POC to a less energetic environment (>10 m in depth). This study provides valuable insights into POC dynamics in high‐turbidity estuarine and coastal environments. It underscores the importance of employing comprehensive modeling approaches to elucidate these complex processes.

Surface Wave Development and Ambient Sound in the Ocean

AbstractWind, wave, and acoustic observations are used to test a scaling for ambient sound levels in the ocean that is based on wind speed and the degree of surface wave development (at a given wind speed). The focus of this study is acoustic frequencies in the range 1–20 kHz, for which sound is generated by the bubbles injected during surface wave breaking. Traditionally, ambient sound spectra in this frequency range are scaled by wind speed alone. In this study, we investigate a secondary dependence on surface wave development. For any given wind‐speed, ambient sound levels are separated into conditions in which waves are 1) actively developing or 2) fully developed. Wave development is quantified using the non‐dimensional wave height, a metric commonly used to analyze fetch or duration limitations in wave growth. This simple metric is applicable in both coastal and open ocean environments. Use of the wave development metric to scale sound spectra is first motivated with observations from a brief case study near the island of Jan Mayen (Norwegian Sea), then robustly tested with long time‐series observations of winds and waves at Ocean Station Papa (North Pacific Ocean). When waves are actively developing, ambient sound levels are elevated 2–3 dB across the 1–20 kHz frequency range. This result is discussed in the context of sound generation during wave breaking and sound attenuation by persistent bubble layers.

Experimental investigation on the relationships between hydrodynamic responses and output properties of flower-like triboelectric nanogenerator in a large wave-flow flume

Triboelectric nanogenerators (TENGs) have emerged as a promising technology for harvesting wave energy and converting it into electrical power. However, the practical application of TENGs in real-world ocean environments has been hindered by a lack of comprehensive data on their hydrodynamic responses and output properties under realistic wave-flow conditions. This gap in the literature has limited our understanding of how to optimize TENG designs for efficient wave energy conversion. In this study, a comprehensive series of experiments were conducted using a large wave-flow flume to investigate the performance of a flower-like TENG (FL-TENG) under various hydrodynamic conditions, including wave height, wave frequency, flow velocity, and structural geometry. The output voltage, motion responses, and cable tension of the FL-TENG were monitored using an electrometer, a machine vision-based displacement measurement system, and tensiometers, respectively. The results show that the relationship between the incident wave-flow area and the FL-TENG's output properties is more complex than a simple “bigger is better” trend. It is also found that the output voltage and hydrodynamic responses of the FL-TENG were positively correlated with the aspect ratio of the rectangular incident wave-flow shape. Importantly, the presence of water flow was observed to significantly inhibit the output properties and hydrodynamic responses of the FL-TENG. These findings provide valuable insights and new design considerations for advancing TENG applications in real-world ocean environments, ultimately contributing to the development of more efficient wave energy conversion technologies.

Suppressing interference from sidelobe coupling in phased-array acoustic Doppler velocimetry based on correlation delay optimization

ABSTRACT Velocity information is important for describing the motion state of an object. Modern underwater navigation systems use the Doppler effect to extract the absolute velocity to the bottom or relative velocity to the water layer from the acoustic backscattering signal. Suppressing interference from sidelobe coupling is very important to improve the accuracy of phased-array acoustic Doppler Velocity Log (DVL) and to realize autonomous navigation in complex ocean environments. This paper proposes an interference suppression method based on optimizing the correlation delay of the pulse-pair algorithm to reduce the sidelobe coupling interference. The results of simulations and experiments show that the proposed method reduces the effect of sidelobe coupling on velocity measurements by 70% on average, which is expected to be useful for improving the autonomous navigation performance of unmanned vehicles in complex underwater environments.

Impact of shallow hydrothermal vent waters on monsoonal copepod distribution and abundance around active volcanic island off northeast Taiwan, West Pacific

Extreme oceanic environments such as shallow hydrothermal vents (HVs) have rarely been investigated with respect to their impact on the water column and its organisms, such as zooplankton. We collected mesozooplankton from the near shore shallow HV areas off northeast Taiwan during three distinct monsoonal periods in 2022. The results showed the occurrence of 99 copepod species belonging to 24 families and 49 genera from a one-year study. The results from similarity percentage (SIMPER) and indicator species analysis (IndVal) identified that top 5 species namely Temora turbinata, Oncaea venusta, Clausocalanus furcatus, Macrosetella gracilis, and Canthocalanus pauper showed variations in their abundance between HV and non-HV sites which contributed to 72.12 % dissimilarity with only four of the species with significantly higher contributions during the SW monsoon season. This distinction is explained by the fact that copepods were negatively affected by HV water. Furthermore, Temora turbinata (3530.7 ± 4967.83 ind. m−3), Calanus sinicus (70.86 ± 163.78 ind. m−3), and Paracalanus parvus (40.47 ± 85.67 ind. m−3) emerging as the dominant species with a clear seasonal succession pattern during the southwest monsoon, northeast-southwest monsoon transition, and northeast monsoon prevailing phase, respectively. The total abundance of copepod was significantly higher during the southwest monsoon than during the other two monsoonal periods (p < 0.01, one-way ANOVA). In contrast, the number of species and the richness index were significantly higher during the northeast-southwest and northeast monsoon than during the southwest monsoon period (p < 0.05, one-way ANOVA) indicating temporal succession in the copepod community.

Design and Implementation of a Multimodal Tilt‐Rotor Unmanned Aerial‐Aquatic Vehicle

ABSTRACTThe unmanned aerial‐aquatic vehicle (UAAV) can be operated in both air and water for scientific and engineering applications. However, the endurance and maneuverability of the UAAV are challenged by the complex multi‐domain tasks. Inspired by the locomotion modes of the tilt‐rotor unmanned aerial vehicle (UAV) and the hybrid underwater glider (HUG), the design and implementation of a multimodal tilt‐rotor UAAV are presented in this paper. This UAAV can repeat trans‐domain and move in both air and underwater. To minimize configuration redundancy and weight of the vehicle, the amphibious structures are implemented, which include a waterproof air tilt‐rotor to provide vector pull for underwater propulsion, a movable buoyant tailplane to adjust the pitch angle for underwater gliding, a distributed variable buoyancy system (DVBS) to control buoyancy, and the hollow wings with a 10° dihedral angle to assist water exit. The vehicle prototype was fabricated, and tested in ocean environments, lakes, and high‐visibility pools. The results demonstrate that the vehicle can perform controllably and repeatedly trans‐domain under disturbed conditions, and the combination of efficient and flexible locomotion modes can enhance the endurance and maneuverability of the vehicle in multidomain environments. In particular, the underwater endurance of over 12 h, and the underwater attitude response rates improve by over 100%. Moreover, the vehicle's weight is decreased by over 39% owing to the implementation of amphibious structures.

Improved identification and tracking of three-dimensional eddies in the Southern Ocean utilizing 3D-U-Res-Net

Oceanic mesoscale eddies are prevalent throughout the global ocean, playing a critical role in material and energy transport while significantly influencing climate change. Accurate characterization of their three-dimensional structures and movement is essential for a quantitative analysis of their transport processes. Traditional eddy detection algorithms have lower successful detection rate and with more limitations, so they fall short in the complex and dynamic ocean environment. The rising trend of applying artificial intelligence (AI) algorithms, due to their efficiency, precision, and automation, addresses this challenge. This study employs the 3D-U-Res-Net algorithm to identify the three-dimensional structures of mesoscale eddies in the Southern Ocean using GLORYS12V1 data from 2011 to 2020. A vector geometry-based eddy detection algorithm (VG) initially identified 1587292 eddy snapshots in the Southern Ocean (2011–2019), which were used for training the 3D-U-Res-Net algorithm. Data from 2020 served as the ground truth and validation set. The successful detection rate of 3D-U-Res-Net algorithm is 100%, which means that it identified all 135734 eddy snapshots from the VG dataset in 2020. For eddy tracking, the VG algorithm counted 18168 eddy tracks, whereas the 3D-U-Res-Net counted 18559, reflecting a 2.15% bias. To reduce uncertainty, eddies with lifespans shorter than two weeks were excluded. The average lifespans and traveling distances for eddies detected by the 3D-U-Res-Net (VG) algorithm were 29.35 (29.61) days and 77.78 (37.60) km, respectively, with the 3D-U-Res-Net identifying eddies with longer traveling distances. The mean radius of eddies detected by the VG algorithm was 43.16 km, while the 3D-U-Res-Net detected eddies with a mean radius of 43.74 km, a 0.58 km increase. We categorized eddies into four three-dimensional structures: bowl-shaped, cone-shaped, lens-shaped, and cylindrical. The VG algorithm identified these structures in proportions of 32%, 31%, 25%, and 12%, respectively, whereas the 3D-U-Res-Net algorithm found 19.48%, 19.58%, 0.04%, and 60.9%, respectively. The 3D-U-Res-Net identified more cylindrical eddies and was approximately ten times faster than the VG algorithm. Overall, this algorithm has good performance and higher efficiency. It is an attempt of using AI for oceanic research, and more works can be carried out in the future.

(Invited) Durability Analysis of Meas with Reversal Tolerant Anodes Under Repeated Cell Reversal Conditions

As regulations on greenhouse gas emissions are being strengthened, polymer electrolyte fuel cells (PEFCs) are being applied as a power source in a variety of applications. Mobility such as cars, ships, trains, airplanes, etc. have dynamic operating conditions. Because these operating conditions affect the durability of fuel cells, many studies have been reported analyzing durability of the membrane electrode assemblies (MEAs) by applying repeated operating conditions. 'Cell Reversal’, where the fuel cell voltage drops below 0V, is one of these operating conditions. This phenomenon is observed when electric energy is continuously consumed under hydrogen starvation conditions at the anode or when the required electric energy suddenly increases.In this talk, first, we attempted to find the optimal additive ratio by controlling the additive content of the electrode. Second, the durability of MEAs with three different types of electrocatalysts and additives was analyzed. Lastly, we will discuss strategies to further improve the durability of MEAs with additives in the anode. Acknowledgements This research was supported by a grant from Endowment project of “Development of Basic Technologies in Eco-friendly Ship Fuel Reliability and Safety Evaluation” funded by Korea Research Institute of Ships and Ocean Engineering (PES5100), and this research was also supported by a grant from “Development on operation and reliability verification technology of 1MW class eco-friendly ship fuel and power system under ocean environment (RS-2021-KS211507/PMS5950) funded by the Ministry of Oceans and Fisheries of Korea