Journal of Geophysical Research-Oceans最新文献

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Reply to Comment by Cao and Yu on “Tidal Modulation of the Fraser River Plume” 对曹、余关于“菲沙河羽流的潮汐调制”的答复
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-12 DOI: 10.1029/2026JC024151
Shumin Li, Rich Pawlowicz
{"title":"Reply to Comment by Cao and Yu on “Tidal Modulation of the Fraser River Plume”","authors":"Shumin Li,&nbsp;Rich Pawlowicz","doi":"10.1029/2026JC024151","DOIUrl":"https://doi.org/10.1029/2026JC024151","url":null,"abstract":"<p>In several papers, we have attempted to discover the degree to which winds, river flow, and tides affected the area of a river plume by considering 19 years of daily images of the plume of the Fraser River in the NE Pacific. To estimate tidal effects, we use stepwise procedure in which seasonal river-flow related variability is first removed, and then a tidal signal is estimated. Cao and Yu noticed that our procedure may have removed a small amount of tidal variability in addition to the river-flow-related variability during the first step. While we did not recognize this particular problem, we were aware of the general difficulties in looking for a small “tida” signal buried within a larger “river flow rate” response and implemented two independent methods to evaluate the tidal modulation of plume area; on re-examination the difference between them is consistent with Cao and Yu's estimate of the bias in the first method. Although we concede that a better statistical estimator could (and perhaps should) be designed for this problem, we believe that our qualitative conclusions remain robust and that, considering other sources of uncertainty, our procedures could reasonably be applied to other locations during an initial analysis.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683593","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}
引用次数: 0
Distribution, Formation, and Evolution of Subsurface Secondary Acoustic Ducts From Global Ocean Modeling and Observations 基于全球海洋模拟与观测的次声管道分布、形成与演化
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-10 DOI: 10.1029/2024JC022230
K. Ravi Prakash, Ramsey R. Harcourt, John B. Mickett, Guangyu Xu, LuAnne Thompson
{"title":"Distribution, Formation, and Evolution of Subsurface Secondary Acoustic Ducts From Global Ocean Modeling and Observations","authors":"K. Ravi Prakash,&nbsp;Ramsey R. Harcourt,&nbsp;John B. Mickett,&nbsp;Guangyu Xu,&nbsp;LuAnne Thompson","doi":"10.1029/2024JC022230","DOIUrl":"https://doi.org/10.1029/2024JC022230","url":null,"abstract":"<p>Monthly mean reanalysis from assimilating global ocean circulation models spanning 27 years is used to study subsurface secondary acoustic ducts, which provide waveguides for the transmission of mid-frequency sound. A systematic diagnosis of secondary ducts from monthly mean temperature and salinity fields characterizes their distribution and properties in two global ocean models. Results from both models are compared against a monthly gridded product derived from Argo float observations to evaluate the climatology, distribution, and formation mechanisms of these ducts. Geographical and seasonal patterns reveal two distinct formation mechanisms for subsurface ducts. Regions dominated by subducted pycnostads, associated with mode waters, exhibit well-mixed layers with weak stratification dominated by temperature. In contrast, ducts formed within the permanent pycnocline are characterized by stratification dominated by salinity, especially in subpolar regions. A constraint limiting bulk stratification of the upward-refracting layer as a function of density ratio or of Turner angle across the layer is obtained from linearized equations of state for density and sound speed. Subsurface ducts diagnosed from nonlinear equations for density and sound speed conform to this approximated constraint, which accounts for the global decomposition of modeled ducts into two partially overlapping branches: one with the upward-refracting layer stratified primarily by salinity and the other, more weakly stratified. The distribution of weakly stratified layers largely conforms to known mode waters. The formation of salinity-dominated upward-refracting layers in ducts is linked to stratification generated annually by one-dimensional processes at the base of deep winter mixed layers, freshened by precipitation and runoff.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022230","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683539","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}
引用次数: 0
Cross-Boundary Heat and Freshwater Transports by Mesoscale Eddies in the Western Subpolar North Atlantic 北大西洋亚极西部中尺度涡旋的跨界热量和淡水输送
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-09 DOI: 10.1029/2025JC023727
Yingjie Liu, Guihua Wang, Yanjiang Lin, Damien Desbruyères, Herlé Mercier
{"title":"Cross-Boundary Heat and Freshwater Transports by Mesoscale Eddies in the Western Subpolar North Atlantic","authors":"Yingjie Liu,&nbsp;Guihua Wang,&nbsp;Yanjiang Lin,&nbsp;Damien Desbruyères,&nbsp;Herlé Mercier","doi":"10.1029/2025JC023727","DOIUrl":"https://doi.org/10.1029/2025JC023727","url":null,"abstract":"<p>The boundary current of the North Atlantic Subpolar Gyre (SPG) is a crucial component of the meridional overturning circulation. Using 18 years (2002–2019) of satellite altimetry and hydrographic profiles, this study provides a comprehensive observational analysis of the role of mesoscale eddies in transporting heat and freshwater across the western boundary of the SPG from the Denmark Strait to Flemish Cap. The eddies are found to predominantly propagate westward across the gyre boundary, transporting water masses with thermohaline properties distinct from those of the adjacent boundary current. When vertically integrated, the eddy-induced transports yield a net offshore-bound heat flux of −0.28 ± 0.07 TW and a net onshore-bound freshwater flux of −0.22 ± 0.05 mSv, respectively, contributing to the cooling and freshening of the boundary current. Distinct regional patterns emerge, with particularly strong offshore heat transport and onshore freshwater transport in the eastern Labrador Sea. These findings improve our understanding of eddy-driven water mass transformation along the SPG boundary currents and provide context for their potential influence on larger-scale North Atlantic circulation.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683611","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}
引用次数: 0
Field Observations of Sea Ice Thickening by Artificial Flooding 人工洪水增厚海冰的野外观测
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-08 DOI: 10.1029/2025JC022738
T. C. Hammer, L. L. van Dijke, A. Shestov, C. Haas, H. Hendrikse
{"title":"Field Observations of Sea Ice Thickening by Artificial Flooding","authors":"T. C. Hammer,&nbsp;L. L. van Dijke,&nbsp;A. Shestov,&nbsp;C. Haas,&nbsp;H. Hendrikse","doi":"10.1029/2025JC022738","DOIUrl":"https://doi.org/10.1029/2025JC022738","url":null,"abstract":"<p>Arctic sea ice is retreating at a high rate, also due to the positive ice-albedo feedback loop: as ice melts and disappears, it reflects less sunlight, further accelerating ocean warming. One proposed way to slow the retreat is by thickening sea ice in winter, increasing its chances of surviving summer melt. This could be achieved by artificially flooding existing sea ice with seawater pumped from below, allowing it to freeze at the surface through exposure to cold air and thicken the ice layer. However, the effectiveness of this approach remains uncertain, as numerical models show contrasting results and few field experiments have been conducted. This study examines the growth and melt of ice through spring and summer after artificial flooding covering <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>1</mn>\u0000 <mo>,</mo>\u0000 <mn>500</mn>\u0000 <mspace></mspace>\u0000 <msup>\u0000 <mi>m</mi>\u0000 <mn>2</mn>\u0000 </msup>\u0000 </mrow>\u0000 <annotation> ${sim} 1,500hspace*{.5em}{mathrm{m}}^{2}$</annotation>\u0000 </semantics></math>, resulting in thickened (+26 cm) snow-covered first-year sea ice. Observations were carried out in Vallunden Lagoon (Van Mijenfjord), Svalbard, from 20 March to 24 June 2024, with flooding and intensive in situ measurements from 11–15 April. Artificial flooding significantly heated the upper two-thirds of the original 90 cm thick ice, increasing salinity. Surface albedo evolution was influenced by specific events such as slush formation, snow drift, and a major meltwater drainage event in spring. Artificial flooding resulted in thicker ice and delayed rotten ice formation by 6 days, but did not delay the disappearance of ice in summer compared to a non-flooded reference site. Experiments at other scales and locations could help reveal how local conditions and flooded area size influence results and the potential of this method.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JC022738","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683399","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}
引用次数: 0
Ocean Mesoscale Processes Heat Atmosphere Over the Western Boundary Currents and Their Extensions 海洋中尺度过程加热西边界气流及其扩展的大气
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-08 DOI: 10.1029/2025JC023452
Zhiqiao Wang, Zhao Jing, Lixin Wu
{"title":"Ocean Mesoscale Processes Heat Atmosphere Over the Western Boundary Currents and Their Extensions","authors":"Zhiqiao Wang,&nbsp;Zhao Jing,&nbsp;Lixin Wu","doi":"10.1029/2025JC023452","DOIUrl":"https://doi.org/10.1029/2025JC023452","url":null,"abstract":"<p>Ocean mesoscale processes are ubiquitous across the global ocean, generating prominent sea surface temperature anomaly (SSTA) that in turn drive turbulent heat flux anomaly (THFA) at the air-sea interface. Although the response of THFA to mesoscale SSTA has been extensively studied, it remains poorly assessed whether the THFA induced by mesoscale SSTA could cause a mean heat exchange between the ocean and atmosphere. Here, we address this issue based on an eddy-resolving coupled global climate simulation. The results show that the response of THFA to mesoscale SSTA is nonlinear primarily due to the response of surface wind speed anomaly to mesoscale SSTA and secondarily to the nonlinearity in the Clausius–Clapeyron relation. Such a nonlinear response of THFA to mesoscale SSTA causes a significant mean heat release of the order of 10 W m<sup>−2</sup> from the ocean to the atmosphere over the western boundary currents and their extensions. Our findings suggest an important role of ocean mesoscale processes in heating the atmosphere, providing new insights into the closure of the ocean and atmosphere heat content budgets.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683425","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}
引用次数: 0
Observation-Based Estimates of Vertical Velocity in the Tropical Upper Oceans 基于观测的热带上层海洋垂直速度估计
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-06 DOI: 10.1029/2025JC023435
Franz Philip Tuchen, Gregory R. Foltz, Renellys C. Perez, Michael J. McPhaden
{"title":"Observation-Based Estimates of Vertical Velocity in the Tropical Upper Oceans","authors":"Franz Philip Tuchen,&nbsp;Gregory R. Foltz,&nbsp;Renellys C. Perez,&nbsp;Michael J. McPhaden","doi":"10.1029/2025JC023435","DOIUrl":"https://doi.org/10.1029/2025JC023435","url":null,"abstract":"<p>Equatorial upwelling plays a crucial role in regulating regional climate variability and biological productivity from seasonal to interannual time scales. Typically, sea surface temperature or surface chlorophyll anomalies are used as proxies for upwelling because of the challenges in directly measuring vertical velocities. Here, we show that using a synthesis product of surface drifter observations, reanalysis winds, and satellite altimetry to infer vertical velocity in the equatorial band (±3°; <i>w</i><sub>eq</sub>) improves the representation of the spatiotemporal characteristics of <i>w</i><sub>eq</sub> compared to estimates from other commonly used products. We focus on the annual mean, seasonal cycle, interannual variations, and long-term trends of vertical velocity estimates, derived by applying the continuity equation to horizontal current divergence in the upper 30 m across the tropical Pacific, Atlantic, and Indian Oceans. Mean <i>w</i><sub>eq</sub> values of 0.6 ± 0.2, 0.3 ± 0.2 and 0.1 ± 0.2 m day<sup>−1</sup> are observed in the Pacific (150°W–90°W), Atlantic (20°W–0°), and Indian Ocean (60°E–90°E), respectively. Vertical transport across 30 m is 46 ± 14 Sv in the Pacific and 8 ± 4 Sv in the Atlantic. Interannual variations in <i>w</i><sub>eq</sub> are primarily driven by climate modes specific to each basin and are up to ±0.4 m day<sup>−1</sup> in the Pacific, ±0.1 m day<sup>−1</sup> in the Atlantic, and up to ±0.6 m day<sup>−1</sup> in the Indian Ocean. From 1993 to 2022, Pacific <i>w</i><sub>eq</sub> significantly increased by 24 ± 13% (0.14 ± 0.07 m day<sup>−1</sup>). This increase in Pacific equatorial upwelling aligns with stronger trade winds and intensified upper-ocean currents.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JC023435","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683222","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}
引用次数: 0
Distribution and Biogeochemical Cycling of Dissolved Copper in the Indian Ocean 印度洋溶解铜的分布与生物地球化学循环
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-06 DOI: 10.1029/2025JC023008
Nirmalya Malla, Sunil Kumar Singh
{"title":"Distribution and Biogeochemical Cycling of Dissolved Copper in the Indian Ocean","authors":"Nirmalya Malla,&nbsp;Sunil Kumar Singh","doi":"10.1029/2025JC023008","DOIUrl":"https://doi.org/10.1029/2025JC023008","url":null,"abstract":"<p>The present study illustrates the distribution of dissolved copper (dCu)—an essential micronutrient for marine phytoplankton—across the Indian Ocean. Our research covers the Arabian Sea, the Bay of Bengal (BoB), the Eastern Equatorial Indian Ocean (EIO), the Southern Sector of the Indian Ocean (SIO) up to 30°S, and the Central Indian Ocean Basin (CIOB) along the GEOTRACES transects GI09 and GI10. Coastal waters of the Northern Indian Ocean exhibit elevated dCu levels, attributed to diverse sources such as riverine input, atmospheric dust, shelf release, and submarine groundwater discharge (SGD). Unlike certain other trace metals, hydrothermal vents are not a significant source of dCu in this region. However, the Java-Sumatra subduction zone and porewaters from polymetallic nodule-rich sediments in the CIOB contribute dCu to deeper waters. The dCu vertical profile reveals a linear increase with depth, driven by reversible scavenging processes and/or benthic flux. This distinguishes dCu from Cadmium (Cd), which follows a typical nutrient-type distribution. Anthropogenic activities, including industrialization, have introduced excess dCu into coastal regions, impacting phytoplankton communities. Notably, the recent prevalence of anthropogenic dust in the BoB may be heightening dCu concentrations to levels that pose toxicity risks, thereby influencing primary productivity and ecosystem community dynamics. Ultimately, this study highlights how external inputs and natural or anthropogenic processes govern dCu distribution. It underscores the need for future research into the resulting impacts on marine ecosystem composition and global biogeochemical cycles.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683112","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}
引用次数: 0
Characterization of the Shallow Oxygen Minimum Zone of the Eastern Tropical North Atlantic 北大西洋东部热带浅层氧最小带的特征
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-06 DOI: 10.1029/2025JC022944
Cláudio Cardoso, Paulo H. R. Calil, Álvaro Peliz, Rui M. A. Caldeira
{"title":"Characterization of the Shallow Oxygen Minimum Zone of the Eastern Tropical North Atlantic","authors":"Cláudio Cardoso,&nbsp;Paulo H. R. Calil,&nbsp;Álvaro Peliz,&nbsp;Rui M. A. Caldeira","doi":"10.1029/2025JC022944","DOIUrl":"https://doi.org/10.1029/2025JC022944","url":null,"abstract":"<p>The Eastern Tropical North Atlantic (ETNA) hosts a shallow Oxygen Minimum Zone (sOMZ) extending roughly from 50 to 250 m depth, where oxygen concentrations typically fall to 40–60 μmol L<sup>−1</sup>. Despite its ecological and biogeochemical importance, the spatial and temporal characteristics of the hypoxic events that shape this sOMZ remain poorly understood. Here we use a high-resolution physical-biogeochemical model to investigate the occurrence, intensity, and structure of hypoxia within the upper 300 m of the ETNA. A combined Eulerian–Lagrangian framework is applied to identify and track Lagrangian Hypoxic Events (LHEs) and to classify them according to the dominant physical processes sustaining them. Coastal and offshore hypoxia exhibit distinct dynamics. Coastal hypoxia is widespread, predominantly seasonal, and strongest along the continental margin, where events are intense but vertically confined near the seabed. Coastal hypoxia peaks in summer–autumn, consistent with seasonal reductions in ventilation, though the underlying mechanisms are not directly diagnosed here. In contrast, offshore hypoxia is primarily controlled by mesoscale eddies that form near the coast, trap low-oxygen waters, and intensify such conditions as they propagate westward. Offshore LHEs display greater spatial extent and vertical reach, particularly during autumn and winter. Although eddy-driven hypoxia dominates offshore volumes, large coastal events with long duration also contribute substantially to the structure of the sOMZ. Together, these results provide the first detailed assessment of hypoxic event dynamics in the ETNA's sOMZ and highlight the need for improved observations to quantify their ecological and biogeochemical impacts.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JC022944","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683445","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}
引用次数: 0
Asymmetric Effects of Topographic Slopes and Bottom Friction on Lagrangian and Eulerian Eddy Diffusivities in Two-Layer QG Flow 地形坡度和底部摩擦对两层QG流中拉格朗日和欧拉涡动扩散系数的不对称影响
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-04 DOI: 10.1029/2025JC023770
Miriam F. Sterl, André Palóczy, J. H. LaCasce, Michiel L. J. Baatsen, Sjoerd Groeskamp
{"title":"Asymmetric Effects of Topographic Slopes and Bottom Friction on Lagrangian and Eulerian Eddy Diffusivities in Two-Layer QG Flow","authors":"Miriam F. Sterl,&nbsp;André Palóczy,&nbsp;J. H. LaCasce,&nbsp;Michiel L. J. Baatsen,&nbsp;Sjoerd Groeskamp","doi":"10.1029/2025JC023770","DOIUrl":"https://doi.org/10.1029/2025JC023770","url":null,"abstract":"<p>We investigate how a topographic slope impacts eddy diffusivities in a two-layer quasi-geostrophic model. There are asymmetric effects of retrograde slopes, where the layer interface and the topography tilt in the same direction, and prograde slopes, where the interface and topography tilt in opposite directions. Moreover, there is asymmetry between the upper and lower layer. Steep retrograde slopes suppress the eddy diffusivity in both layers compared to flat or weak slopes. With a strong prograde slope, coherent, long-lived vortices form in the upper layer; as these are surface-trapped, they are not influenced by topography or bottom friction, and the diffusivity in the upper layer is thus relatively unaffected by the slope. In the lower layer, however, the diffusivities decrease with slope magnitude for both prograde and retrograde slopes. We also compare the Lagrangian diffusivity, derived from particle tracking experiments, and the Eulerian diffusivity, based on the flux-gradient relation for potential vorticity (PV). The two values agree in the upper layer, but not in the lower layer. We present a new expression relating Eulerian and Lagrangian diffusivities, and this correctly captures the differences seen in the lower layer. The difference occurs because bottom friction alters the PV along the particle tracks. The results underline the importance of considering both topographic slopes and bottom friction in parametrizations of mesoscale eddy stirring.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JC023770","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683141","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}
引用次数: 0
Identifying the Extent of River-Influenced Waters of the Transpolar Drift With In Situ Measurements of Dissolved Organic Matter Fluorescence and Seawater Density 利用原位测量溶解有机物荧光和海水密度来确定跨极漂移中河流影响水域的范围
IF 3.4 2区 地球科学
Journal of Geophysical Research-Oceans Pub Date : 2026-04-03 DOI: 10.1029/2024JC022200
Zoé Koenig, Mats A. Granskog, Morven Muilwijk, Achim Randelhoff, Angelika H. H. Renner, Melissa Chierici, Agneta Fransson, Rafael Gonçalves-Araujo, Paul A. Dodd
{"title":"Identifying the Extent of River-Influenced Waters of the Transpolar Drift With In Situ Measurements of Dissolved Organic Matter Fluorescence and Seawater Density","authors":"Zoé Koenig,&nbsp;Mats A. Granskog,&nbsp;Morven Muilwijk,&nbsp;Achim Randelhoff,&nbsp;Angelika H. H. Renner,&nbsp;Melissa Chierici,&nbsp;Agneta Fransson,&nbsp;Rafael Gonçalves-Araujo,&nbsp;Paul A. Dodd","doi":"10.1029/2024JC022200","DOIUrl":"https://doi.org/10.1029/2024JC022200","url":null,"abstract":"<p>The oceanic component of the Transpolar Drift (TPD) is a key component of Arctic Ocean surface circulation. However, our understanding of its spatial extent and influence on the underlying water column remains limited. This study leverages a unique high spatial resolution oceanographic transect from August 2022 (late summer), first to identify in-situ criteria to define the extent of the river-influenced waters of the TPD and then to investigate its characteristics in the western Eurasian Basin. The section stretches from northeast of Greenland across the Amundsen and Nansen Basins to the continental slope north of Svalbard. Large contrasts are observed between the Amundsen and Nansen Basin, including a fresher surface ocean in the Amundsen Basin. By combining hydrography with in-situ measurements of dissolved organic matter fluorescence and dissolved oxygen, we characterize the water masses associated with the oceanic TPD. In our multi-parameter analysis, we find that the combination of the isopycnal 26 kg m<sup>−3</sup> and elevated humic-like fluorescent dissolved matter can be used to identify the vertical and eastward extents of the oceanic TPD dominated by river-influenced waters. The upper halocline beneath the TPD core contains denitrified water with high Apparent Oxygen Utilization, suggesting a contribution from the Chukchi shelf. The interplay between the TPD and underlying water layers is complex: the TPD influences halocline strength but does not appear to affect the depth of the Atlantic Water core. Understanding this interplay is important, as ongoing climate-driven changes in surface circulation and freshwater distribution may alter the TPD, potentially impacting Arctic ecosystem dynamics.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"131 4","pages":""},"PeriodicalIF":3.4,"publicationDate":"2026-04-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022200","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147683241","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}
引用次数: 0
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