Journal of Geophysical Research-Oceans最新文献

{"title":"Identification of Southern Ocean Upwelling From Biogeochemical-Argo Floats","authors":"D. Stappard,&nbsp;B. Fernández Castro,&nbsp;A. Naveira Garabato,&nbsp;T. Tyrrell","doi":"10.1029/2023JC020597","DOIUrl":"https://doi.org/10.1029/2023JC020597","url":null,"abstract":"<p>The Southern Ocean surrounds the continent of Antarctica, linking the southern regions of the Atlantic, Indian, and Pacific Oceans. It plays a fundamental role in the global overturning circulation, and is a location of intense upwelling of deep water. The deep water that upwells is rich in nutrients, depleted in oxygen (O₂), and enriched in carbon dioxide (CO₂). Southern Ocean upwelling is thus important to the global carbon cycle through its impact on global ocean productivity and through its influence on air-sea CO₂ exchange. However, because of its widespread nature in time and space, and its underpinning weak vertical flows, it is challenging to detect Southern Ocean upwelling from observations. In a novel approach, we utilize measurements from Biogeochemical-Argo floats deployed throughout the Southern Ocean by the Southern Ocean Carbon and Climate Observations and Modeling project, to identify Southern Ocean upwelling through its biogeochemical fingerprint. Our approach detects upwelling by examining surface carbon dioxide ([CO₂]) and oxygen ([O₂]) concentration Relative to Saturation (CORS). Differences between observed (calculated from pH for CO₂) and saturating gas concentrations are used to fingerprint upwelling. Spatial analysis of the identified upwelling reveals a latitudinal gradient in upwelling, with the maximum toward the south of the Antarctic Circumpolar Current. Furthermore, our observational diagnostics provides some support of previous model-based propositions of a focalization of Southern Ocean upwelling on hotspots of complex topography. Ongoing analysis with our approach can provide further insight into the nature and spatio-temporal variability of Southern Ocean upwelling.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 6","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JC020597","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144179016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Asymmetric Response of the North Atlantic Gyres to the North Atlantic Oscillation","authors":"Dhruv Bhagtani,&nbsp;Andrew McC. Hogg,&nbsp;Ryan M. Holmes,&nbsp;Navid C. Constantinou,&nbsp;Hemant Khatri","doi":"10.1029/2024JC021997","DOIUrl":"https://doi.org/10.1029/2024JC021997","url":null,"abstract":"<p>The North Atlantic Oscillation (NAO) is a leading mode of atmospheric variability, affecting the North Atlantic Ocean on sub-seasonal to multi-decadal timescales. The NAO changes the atmospheric forcing at the ocean's surface, including winds and surface buoyancy fluxes, both of which are known to impact large-scale gyre circulation. However, the relative role of other physical processes (such as mesoscale eddies and topography) in influencing gyre circulation under NAO variability is not fully understood. Here, we analyze a series of ocean-sea ice simulations using a barotropic vorticity budget to understand the long-term response of the North Atlantic gyre circulation to NAO forcing. We find that for each standard deviation increase in the NAO index, the subtropical and subpolar gyres intensify by 0.90 and 3.41 Sv (1<span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mspace></mspace>\u0000 <mi>S</mi>\u0000 <mi>v</mi>\u0000 <mspace></mspace>\u0000 <mo>≡</mo>\u0000 <mn>1</mn>\u0000 <msup>\u0000 <mn>0</mn>\u0000 <mn>6</mn>\u0000 </msup>\u0000 <mspace></mspace>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mn>3</mn>\u0000 </msup>\u0000 <mspace></mspace>\u0000 <msup>\u0000 <mi>s</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 </mrow>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> $,mathrm{S}mathrm{v} equiv 1{0}^{6},{mathrm{m}}^{3},{mathrm{s}}^{-1}$</annotation>\u0000 </semantics></math>), respectively. The NAO-induced wind stress anomalies drive approximately 90% of the change in the subtropical gyre's interior flow. However, in the subpolar gyre's interior, in addition to wind stress, flow-topography interactions, stratification (influenced by surface heat fluxes), and non-linear advection significantly influence the circulation. Along the western boundary the bottom pressure torque plays a key role in steering the flow, and the vorticity input by the bottom pressure torque is partly redistributed by non-linear advection. Our study highlights the importance of both atmospheric forcing and oceanic dynamical processes in driving long-term gyre circulation responses to the NAO.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 6","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021997","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144171917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Influence of the Advection of Labrador Sea Water on the Decadal Variability of the Eastern Subpolar North Atlantic","authors":"C. Herbaut,&nbsp;M.-N. Houssais,&nbsp;A. C. Blaizot,&nbsp;S. Close","doi":"10.1029/2024JC022269","DOIUrl":"https://doi.org/10.1029/2024JC022269","url":null,"abstract":"<p>The upper ocean heat content of the eastern subpolar North Atlantic (ESPNA) displays large decadal variations, in particular, a warming starting in the mid-1990s followed by a cooling trend from the mid-2000s to the mid-2010s. Using an eddy permitting ice-ocean model, we find a relationship between the eastward propagation of dense water formed in the Labrador and Irminger Seas, the barotropic horizontal circulation and the advective heat convergence in the ESPNA. The time evolution of the 3-year average anomalies of the barotropic streamfunction (BSF) shows a strong resemblance to that of the depth of the deep isopycnals. In particular, the propagation of dense water drives a response of the BSF in the intergyre gyre region. During the warming period, the advection of dense water is associated with a southeastward expansion of the subpolar gyre and a reduction of the supply of cold water from the western subpolar North Atlantic to the upper layers of the ESPNA. Sensitivity experiments suggest that atmospheric forcing can also enhance the trends in the heat content, but the latter cannot be related to trends of the local wind curl. However, circulation changes induced by the wind curl on some specific years can amplify the heat content changes.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 6","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022269","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144171985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Assimilating Observations to Improve Arctic Sea Ice Seasonal Prediction: A Variational Autoencoder Latent Space Particle Filter Approach","authors":"Zhiqiang Chen,&nbsp;Delin Li,&nbsp;Jiping Liu,&nbsp;Jianjun Xu,&nbsp;Qinghua Yang","doi":"10.1029/2024JC022206","DOIUrl":"https://doi.org/10.1029/2024JC022206","url":null,"abstract":"<p>Assimilating observational data is essential for improving Arctic sea ice model prediction, yet the high-dimensional nature of such models poses challenges for applying nonlinear particle filtering methods. To address this, we propose a Latent Space Particle Filter (LSPF) approach that leverages a variational autoencoder (VAE) deep neural network to extract low-dimensional representations of sea ice physical fields. This method compresses the high-dimensional data into a latent subspace, enabling efficient statistical sampling and generating a large number of low-dimensional samples for nonlinear particle filtering. We train the VAE using multiple sea ice reanalysis data sets and conduct historical assimilation experiments using the latest ice-ocean coupled model developed by Princeton University's Geophysical Fluid Dynamics Laboratory. Results indicate that assimilating satellite observations of sea ice concentration and thickness with LSPF during the winter freezing period significantly reduces model errors, particularly for sea ice thickness. All simulations are extended to September without additional assimilation and evaluated with independent satellite observations and mooring data. Findings further demonstrate that wintertime nonlinear particle filter assimilation can improve prediction skill, especially when performed every 3 days, reducing model errors by approximately 30%–50%. Therefore, the LSPF method proposed in this study provides a promising and effective solution for nonlinear data assimilation in realistic high-dimensional geoscience applications.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 6","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022206","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144148418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Mapping of a Mid-Depth Salinity Maximum Intrusion South of New England in June 2021 and Implications for Cross-Shelf Exchange","authors":"Glen G. Gawarkiewicz,&nbsp;Lukas L. Taenzer,&nbsp;Adrienne Silver,&nbsp;Svenja Ryan,&nbsp;Erica Green,&nbsp;Avijit Gangopadhyay,&nbsp;Ruth Musgrave,&nbsp;Frank Bahr,&nbsp;Amy Kukulya,&nbsp;Noa Yoder","doi":"10.1029/2024JC021536","DOIUrl":"https://doi.org/10.1029/2024JC021536","url":null,"abstract":"<p>The Northeast U.S. continental shelf is characterized by relatively cold and fresh shelf waters of Arctic origin, whereas the adjacent Slope Sea is home to warm and salty, Gulf Stream derived waters. These contrasting watermass properties form a strong Shelfbreak Front, which can act as dynamical barrier of exchange between onshore and offshore waters. A shelfbreak exchange process which has been commonly observed in the Middle Atlantic Bight, south of New England, is the mid-depth salinity maximum intrusion, occurring predominantly in the stratified season. It is easily identified within salinity profiles, and yet there have been few hydrographic surveys that have resolved the spatial extent of these features. In order to study these features in more detail, a dedicated research cruise was directed in June 2021 toward mapping and characterization of one of these intrusions. Using a combination of shipboard CTD profiles, Autonomous Underwater Vehicle missions, and a towed microstructure profiler, a strong intrusion was mapped in three-dimensions for the first time. The intrusion penetrated 33 km onshore of the upper portion of the Shelfbreak Front, was 14 km wide in the along-shelf, and was 10–30 m thick. A warm core ring was directly offshore of the intrusion and likely contributed to the initiation of the intrusion. The intrusion contributed about 2.5% additional salt relative to the ambient salinity structure. These intrusions are relevant for the shelf salinity budget as well as the onshore transport of larval fish and are thus an important process for the shelf ecosystem.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 6","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021536","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144148489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Seasonal and Interannual Variability of the Aragonite Saturation Horizon in the California Current System of Baja California","authors":"Norma L. Oliva-Méndez,&nbsp;J. Martín Hernández-Ayón,&nbsp;J. Augusto Valencia-Gasti,&nbsp;Reginaldo Durazo,&nbsp;Eduardo Santamaría-del-Ángel,&nbsp;Simone R. Alin,&nbsp;Richard A. Feely","doi":"10.1029/2024JC021653","DOIUrl":"https://doi.org/10.1029/2024JC021653","url":null,"abstract":"<p>Hydrographic data from cruises of the Investigaciones Mexicanas de la Corriente de California (IMECOCAL) program since 1998 were used to assess the chemical conditions associated with carbon variables in the water column in the transect “Line 100.” Seasonal climatologies along the IMECOCAL line highlight the upwelling season, during which water with different chemical characteristics is transported to the surface. Additionally, interannual events influenced the amplitude and timing of wind-driven coastal upwelling and the region's relative volumes of dominant water mass. Seasonal climatologies of pH, calcium carbonate saturation states, and dissolved inorganic carbon (DIC) concentration were estimated from hydrographic proxy variables. The strength of seasonal upwelling was reflected in the depth of the aragonite saturation horizon (ASH), which was variable nearshore: 90 m (±29 m) in spring and 133 m (±32 m) in winter. Offshore (&gt;50 km), the effect of upwelling diminished, and the ASH was deeper and less variable (spring: 152 m ± 25 m; winter: 151 m ± 28 m). However, aragonite saturation values &lt;1 were found at depths &gt;250 m and were associated with Equatorial Subsurface Water (ESsW) dominance. At seasonal timescales, Subarctic Water (SAW) was found to modulate ASH depth. At interannual scales, ASH was found to be deeper (180 m) during periods of El Niño and shallower (120 m) during La Niña conditions. However, the impacts of El Niño and La Niña events give notable differences in the ASH depth.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 6","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144148488","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interannual Transport Variations in the California Undercurrent Off Vancouver Island: Roles of Remote Coastal Sea Level Variability and El Niño","authors":"Guoqi Han","doi":"10.1029/2024JC021995","DOIUrl":"https://doi.org/10.1029/2024JC021995","url":null,"abstract":"<p>The California Undercurrent is a dominant flow feature and has large impacts on regional ecosystems off the west coast of Canada. So far there is limited knowledge on their interannual transport variations. In this paper a high-resolution ocean circulation model in the northeast Pacific has been established to investigate seasonal and interannual transport variability in the California Undercurrent off Vancouver Island (VI) over 1993–2020. The model forcing includes winds, heat flux, ocean tides, and river runoffs. The model monthly temperature, salinity, and currents are in good agreement with observations at two long-term monitoring site off West VI. Seasonally the California Undercurrent transport increases from spring to fall and decreases in winter. Interannually the transport anomalies of the California Undercurrent are positively correlated with the inflow through the model southern boundary off Oregon and with the Oceanic Niño Index. It is argued that the interannual changes of the California Undercurrent off VI are likely associated with the sea level variability off South California propagating poleward, providing the poleward longshore pressure gradient along the upper continental slope. El Niño enhances the California Undercurrent mainly due to the equatorial coastal sea level variation propagating poleward.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 5","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021995","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144140379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Thirty-One Years of Warming and Oxygen Decline in Massachusetts Bay, a Well-Flushed Non-Eutrophic Temperate Coastal Waterbody","authors":"Daniel L. Codiga,&nbsp;Kenneth E. Keay,&nbsp;P. Scott Libby","doi":"10.1029/2024JC021589","DOIUrl":"https://doi.org/10.1029/2024JC021589","url":null,"abstract":"<p>Warming temperatures and declining oxygen are well-studied in eutrophic coastal systems. To help broaden understanding we investigate non-eutrophic Massachusetts Bay, a representative well-flushed temperate embayment with seasonal thermal stratification, minor river inputs, and residence time of about a month due to exchange with the Gulf of Maine. Long-term trends are computed from de-seasoned measurements over 31 years (1992–2022) at nine bay sites, each sampled at five depths from sea surface to seafloor six times annually. For averages across all stations and depths, the mean warming and oxygen decline rates are +0.0582 (95% C.I. +0.0410 to +0.0759) °C yr⁻¹ and −0.750 (−0.985 to −0.524) μmol kg⁻¹ yr⁻¹ [−0.0246 (−0.0323 to −0.0171) mg L⁻¹ yr⁻¹]. The observed warming reduces oxygen solubility, per seawater properties, at a rate about half the observed oxygen decline. Rates do not differ significantly by site, including near a seafloor outfall releasing treated wastewater effluent, nor at different depths. Because warming is comparable at all depths there is no significant trend in stratification. There is a significant trend of increasing salinity, similarly uniform across sites and depths. A strong hypothesis to explain the warming and salinity trends is advection of Gulf of Maine water into the bay, rather than local influences that could be expected to cause spatially differing rates contrary to those observed. Advection is also a plausible explanation for the observed oxygen decline beyond that due to the solubility decrease. This study highlights potential influence of external ocean forcing on long-term trends in a coastal waterbody.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 5","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021589","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144135862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Evaluating the Response of the Labrador Sea to Greenland Meltwater Influx With High-Resolution Eddy-Rich NEMO Simulations","authors":"P. Hoshyar,&nbsp;C. Pennelly,&nbsp;P. G. Myers","doi":"10.1029/2024JC022102","DOIUrl":"https://doi.org/10.1029/2024JC022102","url":null,"abstract":"<p>The Greenland Ice Sheet has undergone substantial mass loss in recent decades primarily due to oceanic and atmospheric warming, contributing to global sea-level rise and enhanced ocean stratification. This study examines the Labrador Sea's response to increased Greenland freshwater influx using a very high-resolution, eddy-rich configuration of the NEMO ocean model. Two 9-year long experiments with identical setups, except one excluding Greenland runoff, suggest that freshwater influx leads to freshwater content increase (by up to 39%) and intensified stratification (enhanced convective resistance by up to 29%) in the Labrador Sea, whereas heat content remains mainly unchanged (up to 6% increase). Strengthened stratification weakens but does not entirely stop deep convection allowing continued water mass formation within the region (maximum mixed layer depth differences of up to 635 m). A sensitivity analysis indicates warmer, saltier surface waters and colder, fresher subsurface layers when Greenland meltwater is excluded likely driven by reduced lateral exchange from the West Greenland Current system and enhanced southward Arctic Water transport across Davis Strait. Offshore freshwater exchange in the Labrador Sea interior is not solely controlled by Greenland meltwater influx but also by air-sea fluxes and deepwater formation. Over longer timescales exceeding a decade, ongoing freshening and intensified stratification could further disrupt essential oceanic processes with potential consequences for deepwater formation and Atlantic Meridional Overturning Circulation. These findings underscore the importance of accurately representing Greenland meltwater and shelf-basin exchanges in models to improve the predictions of Labrador Sea under future warming.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 5","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022102","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144135861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Characteristics and Fluxes of Vertical and Lateral Particles in the Mesopelagic Northern South China Sea","authors":"Ziming Fang,&nbsp;Zeheng Lin,&nbsp;Binbin Guo,&nbsp;Weifeng Yang,&nbsp;Danyi Su,&nbsp;Mengya Chen,&nbsp;Andi Xu,&nbsp;Qianyong Liang","doi":"10.1029/2024JC022311","DOIUrl":"https://doi.org/10.1029/2024JC022311","url":null,"abstract":"<p>The lateral transport of sediments from the shelf to the ocean interior is ubiquitous on continental margins, exerting great impacts on the characteristics and flux of sinking particles in the mesopelagic ocean. In this study, we determined the biogenic components and stable carbon isotopes in sinking particles collected from the slope of the northern South China Sea using a time series sediment trap. Laterally derived particulate organic carbon (POC_lateral), which originated primarily from marine sources, as indicated by the ratio of POC to particulate nitrogen ratio and POC-δ¹³C, accounted for 31 ± 3% of the total POC flux during the one-and-a-half-year deployment. High fluxes of POC_lateral occurred in April and May 2021, comprising 69 ± 12% and 53 ± 9% of the total POC flux, respectively. This was likely due to the lateral input of shelf sediments entrained by a westward anticyclonic eddy. These allochthonous particles were mainly composed of small (&lt;53 μm) sediments and were depleted in biogenic components, such as POC and biogenic silica (bSi). In contrast, the flux of vertically derived POC (POC_vertical), that is, local biogenic POC, was strongly correlated with the surface Chl-<i>a</i> concentration (<i>R</i>² = 0.62, <i>p</i> &lt; 0.001) and bSi flux (<i>R</i>² = 0.83, <i>p</i> &lt; 0.001), indicating that the POC_vertical flux in the mesopelagic zone was governed by both primary productivity and the growth of diatoms, with the latter being the main controlling factor. Our results highlight that the POC_vertical flux was controlled by the seasonal variations in primary productivity and the phytoplankton community structure, whereas the POC_lateral flux was closely linked to hydrodynamic processes, such as mesoscale eddies.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 5","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144131604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}