Progress in Oceanography最新文献

{"title":"Field observations of internal waves triggered sediment movements at the northern South China Sea continental slope","authors":"Gaibo Zhao ,&nbsp;Changwei Bian ,&nbsp;Wensheng Jiang ,&nbsp;Tao Wang ,&nbsp;Xiaolei Liu ,&nbsp;Jiwei Tian ,&nbsp;Yonggang Jia","doi":"10.1016/j.pocean.2024.103412","DOIUrl":"10.1016/j.pocean.2024.103412","url":null,"abstract":"<div><div>Internal ocean waves, such as internal tides and internal solitary waves (ISWs), have strong horizontal and vertical velocities and play an important role in ocean energy and material exchange. Field observations indicated that internal waves had a significant effect on hydrodynamics and sediment transport on the continental shelf. However, there remained a lack of field observations on how internal waves affect sediment transport on continental slopes. In this study, a seabed observation system was set up on the continental slope of the South China Sea for 13 days, which measured the high spatiotemporal resolution velocity and mixing of the internal tides and ISWs and sediment movements in the bottom boundary layer. The results showed that the internal tides and ISWs caused strong flows of more than 0.20 m/s near the seabed of the slope, which was much higher than the local sub-inertial currents (0.03 m/s) and barotropic tides (0.03 m/s). The velocity enhancement caused by internal tides and ISWs increased the bottom shear stress from 0.01 to 0.08 Pa. When the internal tidal velocity increased, the suspended sediment concentration (SSC) increased substantially from 5 mg/L to more than 40 mg/L. When the strongest ISWs passed through the observation site, the SSC increased several times, reaching 19 mg/L. Both internal tides and ISWs agitated seabed sediment and transported it downwards along the slope with sediment transport flux of 0.26 × 10^-3 and 0.08 × 10^-3 kg m⁻² s⁻¹, respectively.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103412"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142925065","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":"Community structure of fish larvae associated with advections of the Kuroshio and its neighboring waters","authors":"Toru Kobari ,&nbsp;Yusuke Manako ,&nbsp;Airi Hara ,&nbsp;Kaori Yamanoue ,&nbsp;Takafumi Azuma ,&nbsp;Ryuji Fukuda ,&nbsp;Yi-Chen Wang ,&nbsp;Masafumi Kodama ,&nbsp;Gen Kume","doi":"10.1016/j.pocean.2024.103386","DOIUrl":"10.1016/j.pocean.2024.103386","url":null,"abstract":"<div><div>The Kuroshio has been long thought to be disadvantageous as nursery grounds for larval fishes due to the low plankton standing stocks under the oligotrophic conditions. Despite of the potential risk for survival and growth, early life stages of various fishes appear abundantly in the Kuroshio and its neighboring waters. Here, we report what kind of taxonomic groups establish community structure of larval fishes in the Continental shelf waters (CW) and the Kuroshio (KW). 16 orders and 78 families were classified in the present study. Mesopelagic fishes more abundantly appeared in the KW than in the CW, while larval fish abundance was not different between the two areas. Multivariate analysis demonstrated the regional difference of the taxonomic compositions, represented by Callionymidae, Bothidae, Labridae and Bregmacerotidae for the CW and Gonostomatidae, Myctophidae and Notosudidae for the KW. Abundance of fish larvae to ambient salinity exhibited significantly positive correlations for Gonostomatidae, <em>Sigmops gracilis</em> and <em>Myctophum orientale</em> predominated in the KW and negative correlations for Labridae appeared abundantly in the CW. These results suggest that mixture of advected specimens from the coastal and Kuroshio waters also contribute to larval fish community with high biodiversity and comparable abundance between the Kuroshio and its neighboring waters.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103386"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142788910","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}

{"title":"A decade-long flow reversal in the intergyre region of the eastern north Atlantic","authors":"César González-Pola ,&nbsp;Raquel Somavilla ,&nbsp;Rocío Graña ,&nbsp;Amaia Viloria ,&nbsp;Laura Ibáñez-Tejero","doi":"10.1016/j.pocean.2024.103406","DOIUrl":"10.1016/j.pocean.2024.103406","url":null,"abstract":"<div><div>Two hydrographical shifts observed within the last two decades around north/northwestern Iberia, in the mid-latitudes of the eastern North Atlantic, reveal a contrasting behaviour of the weakly circulating reservoir known as the intergyre region. In 2005, a strong winter mixing caused an abrupt salinity increase at mid-depths corresponding to East North Atlantic Central Waters core levels (300–500 m), thus transforming this water mass into a saltier/denser variety. Such shift altered spatial density fields on a broader scale, causing this region classically described as flowing southwards and feeding the subtropical gyre to experience a lasting flow reversal. The reversal brought the region into milder and saltier southern-like conditions and weakened the strength of upwelling in southern Biscay. In 2014, freshening and cooling was observed for the first time since the early 1990s, a process enhanced in the following years accompanied by the restoration of southwards flow and southern Biscay upwelling conditions previously known. The decade-long reversal flow stage meant a temporal boost of ongoing meridionalisation trends attributed to climate change affecting ecosystems, while subsequent recovery to traditional circulation brought the region back to a classical more boreal character. We discuss the uniqueness or possible recurrence on larger timescales of this singular reversed mode circulation event.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103406"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097958","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}

{"title":"Control of simulated ocean ecosystem indicators by biogeochemical observations","authors":"S. Ciavatta ,&nbsp;P. Lazzari ,&nbsp;E. Álvarez ,&nbsp;L. Bertino ,&nbsp;K. Bolding ,&nbsp;J. Bruggeman ,&nbsp;A. Capet ,&nbsp;G. Cossarini ,&nbsp;F. Daryabor ,&nbsp;L. Nerger ,&nbsp;M. Popov ,&nbsp;J. Skákala ,&nbsp;S. Spada ,&nbsp;A. Teruzzi ,&nbsp;T. Wakamatsu ,&nbsp;V.Ç. Yumruktepe ,&nbsp;P. Brasseur","doi":"10.1016/j.pocean.2024.103384","DOIUrl":"10.1016/j.pocean.2024.103384","url":null,"abstract":"<div><div>To protect marine ecosystems threatened by climate change and anthropic stressors, it is essential to operationally monitor ocean health indicators. These are metrics synthetizing multiple marine processes relevant to the users of operational services. In this study, we assess whether selected ocean indicators simulated by operational models can be effectively constrained (i.e., controlled) by biogeochemical observations, by using a newly proposed methodological framework. The method consists in firstly screening the sensitivities of the indicators with respect to the initial conditions of the observable variables. These initial conditions are perturbed stochastically in Monte Carlo simulations of one-dimensional configurations of a multi-model ensemble. Then, the models are applied in three-dimensional ensemble assimilation experiments, where the reduction of the ensemble variance corroborates the controllability of the indicators by the observations. The method is applied to ten relevant ecosystem indicators (ranging from inorganic chemicals to plankton production), seven observation types (representing data from satellite and underwater platforms), and an ensemble of five biogeochemical models of different complexity, employed operationally by the European Copernicus Marine Service. Our results demonstrate that all the indicators are controlled by one or more types of observations. In particular, the indicators of phytoplankton phenology are controlled and improved by merged observations of surface ocean colour and chlorophyll profiles. Similar observations also control and reduce the uncertainty of the plankton community structure and production. However, we observe that the uncertainty of trophic efficiency and particulate organic carbon (POC) increases when chlorophyll-a data are assimilated. This may reflect reduced model skill, though the unavailability of relevant observations prevents a conclusive assessment. We recommend that the controllability assessment proposed here becomes a standard practice in the design of operational monitoring, reanalysis, and forecast systems. Such standardization would provide users of operational services with more accurate and precise estimates of ocean ecosystem indicators.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103384"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097960","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}

{"title":"Observing ENSO-modulated tides from space","authors":"Haidong Pan ,&nbsp;Tengfei Xu ,&nbsp;Zexun Wei","doi":"10.1016/j.pocean.2024.103410","DOIUrl":"10.1016/j.pocean.2024.103410","url":null,"abstract":"<div><div>The understanding of sea level variability is fundamental for coastal communities with high population density. As important parts of sea levels, tides are often overlooked because they tend to be regarded as simple periodic oscillations by numerous studies. In fact, due to the interference of various non-astronomical factors, observed tides are non-stationary and display multi-time scale variability. Here, we focus on inter-annual tidal variations induced by El Niño-Southern Oscillation (ENSO) in the western Pacific. Although satellite altimeters have been widely used in tidal research, to date, inter-annual tidal changes from satellite altimeters are never reported. Classical harmonic analysis (CHA) model with moving windows is inappropriate for satellite altimeter records due to tidal aliasing originated from long-period sampling intervals. In this paper, we successfully quantify the influences of ENSO on tides from multi-satellite altimeters through a revised harmonic analysis (RHA) model which directly builds ENSO forcing into the basic functions of CHA. To eliminate mathematical artifacts caused by over-fitting, Lasso regularization is applied in the RHA model to replace widely-used ordinary least squares. The performances of RHA are generally better than those of CHA as a result of considering the impacts of ENSO. The combination of RHA and satellite altimeters extends the studies on tidal evolution using spatially limited tide gauges. Compared to diurnal tides, it is found that semi-diurnal tides are more vulnerable to ENSO in the western Pacific. Of note, both linear and non-linear tidal responses to ENSO show significant spatial heterogeneity. Moreover, as a universal method, ENSO index used in this study can be replaced by other factors such as river flow and sea waves to explore tidal evolution driven by other physical processes.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103410"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141153","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":"Spatio-temporal changes in the macrozooplankton community in the eastern Indian sector of the Southern Ocean during austral summers: A comparison between 1996 and 2018–2019","authors":"Ippei Urabe ,&nbsp;Kohei Matsuno ,&nbsp;Rikuto Sugioka ,&nbsp;Ryan Driscoll ,&nbsp;Sara Driscoll ,&nbsp;Fokje L. Schaafsma ,&nbsp;Atsushi Yamaguchi ,&nbsp;Ryuichi Matsukura ,&nbsp;Hiroko Sasaki ,&nbsp;Hiroto Murase","doi":"10.1016/j.pocean.2025.103414","DOIUrl":"10.1016/j.pocean.2025.103414","url":null,"abstract":"<div><div>Several large-scale studies have examined the spatial and temporal (seasonal and interannual) variability in macrozooplankton communities in the eastern Indian sector of the Southern Ocean. In this study, variability in these communities was analyzed using samples collected by the RMT8 during the KY1804 survey, conducted between 80° and 150° E during the austral summer of 2018–2019. Furthermore, these findings were compared with those of the BROKE survey conducted in 1996. Using cluster analysis, the macrozooplankton community was divided into six groups. In both surveys, the zooplankton communities varied between the southern and northern stations of the sampling areas, though their distribution patterns differed between the two years. During the KY1804 survey, <em>Thysanoessa macrura</em> was more prevalent in the western region, while <em>Themisto gaudichaudii</em> and chaetognaths were more abundant in the eastern region; <em>Salpa thompsoni</em> dominated in the eastern region during the BROKE survey. Water temperature had the strongest influence on the macrozooplankton community during the KY1804 survey, whereas salinity was the primary influencing factor during the BROKE survey. This difference may largely reflect differences in sampling timing and latitudinal coverage, though a southward shift in the southern boundary of the Antarctic Circumpolar Current between the surveys may also have contributed. Hydrographic changes over the two decades between 1996 and 2019 likely affected the macrozooplankton community in this region, though differences in spatial and temporal survey coverage complicate interpretation of the results.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103414"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141158","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":"A predictive krill distribution model for Euphausia pacifica and Thysanoessa spinifera using scaled acoustic backscatter in the Northern California Current","authors":"S. Derville ,&nbsp;J.L. Fisher ,&nbsp;R.L. Kaplan ,&nbsp;K.S. Bernard ,&nbsp;E.M. Phillips ,&nbsp;L.G. Torres","doi":"10.1016/j.pocean.2024.103388","DOIUrl":"10.1016/j.pocean.2024.103388","url":null,"abstract":"<div><div>Euphausiids (krill) are globally significant zooplankton prey for many commercially important or endangered predator species. In the productive upwelling system of the Northern California Current (NCC), two krill species, <em>Euphausia pacifica</em> and <em>Thysanoessa spinifera,</em> dominate the preyscape and constitute an important food resource for many seabirds, cetaceans, and fish. In this study, we use five years of hydroacoustic and net tow data collected in the NCC to develop integrative models predicting acoustic backscatter scaled for <em>E. pacifica</em> or <em>T. spinifera</em> separately. Boosted Regression Trees and Generalized Additive Models are applied in an original ensemble hurdle framework to predict krill presence and abundance from a diverse set of topographic and oceanographic predictors. Krill metrics had significant relationships with seabed depth, distance to submarine canyons, and variables indicative of dynamic ocean conditions (e.g., total deviance explained in acoustic data: 25 % in the presence-absence model &amp; 49 % in the abundance model). Predictions of krill abundance at 5 km resolution averaged by month indicate differential habitat preferences between the two species: <em>T. spinifera</em> was constrained to the continental shelf, around and inshore of the 200 m isobath, whereas <em>E. pacifica</em> was found in greater abundances just offshore of the 200 m isobath and into offshore water in lower abundances. <em>E. pacifica</em> was generally more abundant than <em>T. spinifera</em> (10:1.3 ratio). Both species increased in abundance in the spring and summer, followed by a rapid decline in the fall, and lowest abundances in the winter. These models can produce fine-scale spatial and year-round weekly predictions of <em>E. pacifica</em> and <em>T. spinifera</em> abundance in the NCC, which will provide essential knowledge and new spatial layers about critical ecosystem components to support research and management.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103388"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097086","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}

{"title":"Baseline matters: Challenges and implications of different marine heatwave baselines","authors":"Kathryn E. Smith ,&nbsp;Alex Sen Gupta ,&nbsp;Dillon Amaya ,&nbsp;Jessica A. Benthuysen ,&nbsp;Michael T. Burrows ,&nbsp;Antonietta Capotondi ,&nbsp;Karen Filbee-Dexter ,&nbsp;Thomas L. Frölicher ,&nbsp;Alistair J. Hobday ,&nbsp;Neil J. Holbrook ,&nbsp;Neil Malan ,&nbsp;Pippa J. Moore ,&nbsp;Eric C.J. Oliver ,&nbsp;Benjamin Richaud ,&nbsp;Julio Salcedo-Castro ,&nbsp;Dan A. Smale ,&nbsp;Mads Thomsen ,&nbsp;Thomas Wernberg","doi":"10.1016/j.pocean.2024.103404","DOIUrl":"10.1016/j.pocean.2024.103404","url":null,"abstract":"<div><div>Marine heatwaves (MHWs), prolonged periods of unusually high ocean temperatures, significantly impact global ecosystems. However, there is ongoing debate regarding the definition of these extreme events, which is crucial for effective research and communication among marine scientists, decision-makers, and the broader public. Fundamental to all MHW analyses is a clearly defined background oceanic climate – i.e., a temperature ‘baseline’ against which the MHW is defined. While a single approach to implementing a baseline may not be suitable for all MHW research applications, the choice of a baseline for analysing MHWs must be intentional as it affects research outcomes.</div><div>This perspective examines baseline choices and discusses their implications for marine organism and ecosystem risks, and their relevance in communicating MHW characteristics and metrics to stakeholders, policymakers, and the public. In particular we analyse five different baseline approaches for computing MHW statistics, assess their technical differences, and discuss their ecological implications. Different baselines suggest widely different trends in MHW characteristics in a warming world. This would, for example, imply differences in future risk, reflective of marine organisms with different adaptive potential, thereby affecting recommendations for management strategies. We also examine the consequences of different baseline choices on ease of implementation and communication with wider audiences. Our analyses highlight the need to clearly specify a chosen baseline in MHW studies, and to be mindful of its implications for MHW statistics, practical considerations, and interpretations concerning the adaptive capacities of marine organisms, ecosystems and human systems. The challenges and implications of different MHW baselines highlighted here have similar relevance in research and communication for other branches of climate extremes.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103404"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097957","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}

{"title":"Estimating the western North Atlantic Subtropical Gyre zonal currents in 2021 through single- and three-box inverse models","authors":"Daniel Santana-Toscano,&nbsp;M.Dolores Pérez-Hernández,&nbsp;Cristina Arumí-Planas,&nbsp;Alonso Hernández-Guerra","doi":"10.1016/j.pocean.2025.103415","DOIUrl":"10.1016/j.pocean.2025.103415","url":null,"abstract":"<div><div>The western North Atlantic Subtropical Gyre comprises the warm Gulf Stream (GS) and the cold Deep Western Boundary Current (DWBC), which are the main currents of the Atlantic Meridional Overturning Circulation (AMOC). Hydrographic sections conducted at 66°W (A22) and 52°W (A20) in the western North Atlantic Subtropical Gyre (NASG) have sampled these currents in 1997, 2003, 2012, and 2021. Both single- and three-box inverse models are used to compute mass, heat, and freshwater transport to the hydrographic data of 2021 with no significant differences between methodologies. This study reveals a substantial change in the GS mass transport at both 52°W and 66°W in spring 2021 compared to spring 2012 and summer 1997, but no changes compared to fall 2003. Conversely, the DWBC shows no significant modification between spring 2021 and previous cruises. Moreover, the North Brazil Current mass transport, which is sampled by the A20 section, presents the downstream weakening showcased previously. Heat and freshwater fluxes are not significantly different from zero, therefore the water volumes enclosed by the A20 and A22 sections do not reflect a net air-sea flux in 2021. Although the GS exhibits interdecadal variability, the lack of other changes over time in this area suggests a general stability in the environmental and forcing conditions. This study highlights the consistent mass transports of the main AMOC currents in the western NASG, particularly the GS and DWBC, emphasizing their stability and importance in broader climate and oceanographic processes.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103415"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143141160","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}

{"title":"Machine learning algorithm reveals surface deoxygenation in the Agulhas Current due to warming","authors":"T.B. Mashifane ,&nbsp;L. Braby ,&nbsp;M. Pikiso ,&nbsp;S. Sunnassee–Taukoor ,&nbsp;R.S. Rapolaki ,&nbsp;M.N. Ragoasha","doi":"10.1016/j.pocean.2024.103407","DOIUrl":"10.1016/j.pocean.2024.103407","url":null,"abstract":"<div><div>The Agulhas Current is the strongest western boundary current (WBC) in the Southern Hemisphere with a significant impact on the global climate. Through the Agulhas leakage, it transports warm, saline waters into the South Atlantic Ocean. In recent years, a warming trend has been highlighted in the Agulhas Current, with possible implications for dissolved oxygen ([O₂]) due to the link between warming and reduced solubility – dynamics that remain relatively unknown in the region. To address this knowledge gap, we use the random forest regression algorithm to predict near–surface [O₂] from multiple predictors in the Agulhas Current, presenting the first analysis of these dynamics. The Agulhas–RFR algorithm predicts [O₂] exceptionally well, with permutation importance from the ensemble indicating that sea surface temperature (SST) is the highest–ranking predictor. Seasonal changes in solubility, wind, and productivity drive [O₂] and the [O₂] flux in the Agulhas Current. The seasonal [O₂] flux to the atmosphere reaches –1.84 mol m⁻² yr⁻¹ during the austral winter across the Agulhas Current. A significant decreasing [O₂] trend of up to –7 µmol kg⁻¹ yr⁻¹, attributed to warming, is revealed for the period from 2000 to 2023. Strengthening westerlies and cooling contribute to [O₂] drawdown towards the Indian Ocean gyre. The Agulhas–RFR algorithm reveals a declining [O₂] trend of –2.29 ± 0.61 µmol kg⁻¹ yr⁻¹ across the Agulhas Current for the study period, representing a 1.4% deoxygenation rate, which is slightly higher than global estimates.</div></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":"231 ","pages":"Article 103407"},"PeriodicalIF":3.8,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142821059","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}