Helena C. Frazão, Uwe Send, Adrienne J. Sutton, Mark D. Ohman, Matthias Lankhorst, Todd R. Martz, Jeffrey Sevadjian
{"title":"Open Ocean Versus Upwelling Regimes: Air-Sea CO2 Fluxes and pCO2 Inter-Annual Variability in the Southern California Current System","authors":"Helena C. Frazão, Uwe Send, Adrienne J. Sutton, Mark D. Ohman, Matthias Lankhorst, Todd R. Martz, Jeffrey Sevadjian","doi":"10.1029/2024JC022126","DOIUrl":"https://doi.org/10.1029/2024JC022126","url":null,"abstract":"<p>Two moorings equipped with autonomous air-sea CO<sub>2</sub> instrumentation located in the Southern California Current System were used to examine the seasonal and interannual variability of the surface partial pressure of carbon dioxide in seawater (<i>p</i>CO<sub>2,sw</sub>) and the air-sea CO<sub>2</sub> flux between 2008 and 2022. These two moorings are in two distinct oceanographic regimes: offshore, centered in the California Current (CCE1), and nearshore within the coastal upwelling regime (CCE2). The offshore seasonal cycles of the surface <i>p</i>CO<sub>2,sw</sub> and CO<sub>2</sub> flux are driven by sea surface temperature (SST) seasonality and at the nearshore site by dissolved inorganic carbon (DIC) concentration changes linked with seasonal upwelling. The resulting net annual CO<sub>2</sub> flux at CCE1 is −0.52 molC m<sup>−2</sup> year<sup>−1</sup> (sink), while at CCE2, the best estimate for the long-term CO<sub>2</sub> flux mean is 0.23 molC m<sup>−2</sup> year<sup>−1</sup> (source). The interannual variability at the offshore site is mainly controlled by SST, where warm anomalies (El Niño and Marine Heatwaves) cause anomalous CO<sub>2</sub> outgassing, and cold anomalies (La Niña) increase CO<sub>2</sub> ingassing. Conversely, at the nearshore site, the strength (or absence of) upwelling of DIC-rich water associated with cold (or warm anomalies) results in increased outgassing (or ingassing) of CO<sub>2</sub>. Long-term trends in <i>p</i>CO<sub>2,sw</sub> approximately follow the atmospheric CO<sub>2</sub> increase. At the offshore site, the DIC trend is consistent with air-sea fluxes, keeping the CO<sub>2</sub> equilibrium between air and water. At the nearshore site, the DIC trend has a similar magnitude but could also result from changing water-mass composition or concentration due to freshwater loss.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022126","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144573861","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}
Jiayue Chen, Wenyan Zhang, Lucas Porz, Peter Arlinghaus, Ulrike Hanz, Moritz Holtappels, Corinna Schrum
{"title":"Physical Mechanisms of Sediment Trapping and Deposition on Spatially Confined Mud Depocenters in High-Energy Shelf Seas","authors":"Jiayue Chen, Wenyan Zhang, Lucas Porz, Peter Arlinghaus, Ulrike Hanz, Moritz Holtappels, Corinna Schrum","doi":"10.1029/2025JC022622","DOIUrl":"https://doi.org/10.1029/2025JC022622","url":null,"abstract":"<p>Mud depocenters in shelf seas serve as a key element in the source-to-sink system of sediment transport on the Earth surface. Despite their undoubtful importance, physical mechanisms for formation, sediment budgeting, and cycling of localized depocenters in high-energy environments remain largely unknown. This study aims to fill the knowledge gap by focusing on sediment dynamics related to a localized mud depocenter in the southern North Sea. By combining field observation with 3-dimensional numerical simulations, we analyzed hydrodynamics and sediment dynamics over a 3-year period. Our results indicate a persistent transport of fine-grained sediments toward the depocenter and subsequent trapping resulting in accumulation, with distinct seasonal and spatial variations in the net depositional rate. The interaction of wind-driven coastal circulation with two distinct frontal systems—a salinity front and a tidal mixing front—emerges as a key mechanism of sediment dynamics. While the salinity front remains persistently over the depocenter, promoting sediment deposition year-round, the tidal mixing front appears primarily in summer, limiting sediment deposition. Sediment flows from offshore and along the coast provide major supply to the depocenter, while contemporary riverine sediment outflows contribute only marginally. Southwesterly winds enhance erosion and northerly winds promote deposition in the depocenter. Additionally, short-term extreme events significantly contribute to annual net sedimentation. Our work highlights the critical importance of frontal systems and extreme events for mud depocenter development in high-energy shelf seas.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JC022622","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558178","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":"Aggregation of Suspended Particles Limited by Preferential Settling","authors":"Enpei Li, Kai Wirtz","doi":"10.1029/2025JC022471","DOIUrl":"https://doi.org/10.1029/2025JC022471","url":null,"abstract":"<p>In coastal waters, the settling velocity of suspended particulate matter (SPM) is primarily governed by particle size, which varies during tidal cycles due to aggregation and disaggregation. Although high turbulence is typically viewed as the primary factor limiting particle size through disaggregation, the large variation in turbulence level does not fully explain the limited variation in mean particle size observed during tidal cycles. This study aims to identify the key processes driving SPM size dynamics and assess their relative influence. We introduce preferential settling into a distribution-based SPM-aggregation model, where larger particles settle faster, effectively removing them from the water column. Our model, applied to both lab and field cases, demonstrates that preferential settling significantly limits particle size, particularly in shallow, SPM-rich waters, as it is independent of turbulence. Changes in particle size range only become significant on timescales beyond a few tidal cycles, and are driven by factors such as biological ones. To account for these changes, we introduced a time-dependent reduction in coagulation efficiency to represent the degradation of organic matter over time. Biological processes such as this degradation should be considered in future studies focused on longer timescales, whereas turbulence-independent processes such as preferential settling need to be included in SPM models for tidal-scale dynamics.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2025JC022471","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558176","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":"Deep Eddy Energy in the Southern Philippine Basin","authors":"Weidong Ma, Jianing Wang, Fan Wang, Hang Zhang","doi":"10.1029/2024JC021495","DOIUrl":"https://doi.org/10.1029/2024JC021495","url":null,"abstract":"<p>The deep eddy activities, which contain a pronounced portion of kinetic energy, are the most energetic form of flow in the deep ocean. However, the dynamics of deep eddies are inadequately understood. Deep intraseasonal variability (ISV) and eddy kinetic energy (EKE), as detected in velocity measurements from four moorings in the Southern Philippine Basin, are generally separated from the upper ocean and vertically coherent below 1,500 m. Combined with the analysis of observed temperature and salinity and outputs from an eddy-resolving reanalysis product, it is confirmed that the events causing deep ISV are deep mesoscale eddies. The energetics of deep eddies are examined by calculating the time derivative of EKE and its potential contributors during the evolution of a fixed eddy. Our energetics analysis reveals that the generation of the deep eddy is predominantly facilitated by vertical energy redistribution through pressure work between upper and deep layers, with energy primarily sourced from upper-ocean perturbations. Dissipation, inverse kinetic energy cascade, and horizontal pressure fluxes ultimately contribute to the extinction of the deep eddy. During the mature stage of the deep eddy, energy fluxes from pressure work and conversions between EKE and eddy available potential energy are notably high, although the dominant contributors vary over time. This work highlights that the deep eddy energy comes from the upper-ocean eddy, and pressure work plays a crucial role in bridging the energetics of the upper and deep layers.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558175","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":"Local Winds Induce the Upper-Layer Kuroshio Intrusion Northeast of the Taiwan Island","authors":"Yixuan Han, Hui Wu","doi":"10.1029/2024JC021819","DOIUrl":"https://doi.org/10.1029/2024JC021819","url":null,"abstract":"<p>The shoreward intrusion of upper-layer Kuroshio water northeast of the Taiwan Island is a key process for ocean-shelf sea exchanges in the western boundary of subtropical Pacific Ocean. Yet, the underlying dynamic mechanisms remains unclear. Here in this study, causality analysis was first conducted based on satellite and reanalysis data, which suggested that local winds rather than the upstream Kuroshio transport or the surface cooling play a primary role. Numerical model experiments further confirmed this point. In winter, the downwelling-favorable northerly wind reduces the sea level in the middle shelf through Ekman pumping; whereas, the high sea level at the shelf break, due to the northward-flowing Kuroshio, slightly increases. The enhanced shoreward barotropic gradient force then pushes Kuroshio to the shelf once it loses the support of the island. Consequently, a horizontal difference in temperature, thus density, is formed by the intrusive warm water, which is further amplified by the differential air-sea heat flux. The resultant baroclinic effect regulates the path of intrusive water, forming an anticyclonic loop. In summer, the absence of these two effects results in a much weaker upper-layer Kuroshio intrusion. In autumn and spring, the differential cooling effects are negligible, and the barotropic effect of episodic northerly winds alone can induce a weak intrusion, but the anticyclonic loop is absent. In short, local winds directly trigger the upper-layer Kuroshio intrusion northeast of the Taiwan Island; other effects, such as differential cooling, are secondary.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536849","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}
Qianru Niu, Yanqing Feng, Si Chen, Yan Li, Jianghua Lv, Hanxiang Su, Lin Mu
{"title":"The ENSO Modulated Wave Climate Over the Northern South China Sea Under the Collective Impact of Monsoon and Tropical Cyclones","authors":"Qianru Niu, Yanqing Feng, Si Chen, Yan Li, Jianghua Lv, Hanxiang Su, Lin Mu","doi":"10.1029/2024JC020966","DOIUrl":"https://doi.org/10.1029/2024JC020966","url":null,"abstract":"<p>Using 30-year simulations (1990–2020) with a validated third-generation wave model, we investigated how El Niño-Southern Oscillation (ENSO) drives seasonal wave climate variability in the northern South China Sea (SCS). Results reveal distinct ENSO impacts across seasons. Spring/winter waves respond to monsoon shifts, with El Niño reducing wave heights and La Niña amplifying extreme waves (the 95th-percentile significant wave heights, <i>H</i><sub><i>s95</i></sub>) via intensified winter monsoon. An exception occurs in the Gulf of Tonkin, where El Niño elevates <i>H</i><sub><i>s95</i></sub> during the winter monsoon season through localized resonance. Summer/fall waves vary with ENSO's reorganization of tropical cyclone (TC) tracks aligning with ENSO-modulated subtropical ridge changes. Specifically, Eastern Pacific (EP) El Niño concentrates TC near the Luzon Strait, boosting extreme waves in the northeast SCS. Fall coastal energy declines under EP El Niño corresponding to the suppressed basin-wide TC activity. The findings advance predictive insights for the wave climate in monsoon and TC-driven subtropical marginal seas under ENSO variability, addressing the need for localized climate adaptation strategies in marginal seas that are under multi-scale atmospheric forcing.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144536850","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}
Runqiu Huang, Junyu He, Zhenyu Wu, George Christakos, Saima Sultana, Yaojia Zhu, Dan Li, Carlos M. Duarte, Jiaping Wu
{"title":"Time-Frequency Analysis Reveals That Seaweed Farming Enhances Phytoplankton Resilience Under ENSO Events","authors":"Runqiu Huang, Junyu He, Zhenyu Wu, George Christakos, Saima Sultana, Yaojia Zhu, Dan Li, Carlos M. Duarte, Jiaping Wu","doi":"10.1029/2024JC022289","DOIUrl":"https://doi.org/10.1029/2024JC022289","url":null,"abstract":"<p>The El Niño-Southern Oscillation (ENSO), a key driver of interannual climate variability, significantly influences marine phytoplankton dynamics. Rising sea surface temperatures (SST) have further stimulated the occurrence of phytoplankton blooms, potentially increasing the role of seaweed farming in regulating phytoplankton communities. However, the impact of seaweed farming on the resilience of phytoplankton to ENSO events is still poorly understood. Here, using integrated in situ monitoring data from a high-yield seaweed farm in China, combined with satellite chlorophyll (Chl) data and time-frequency analysis, we find that seaweed farming regulates phytoplankton blooms and their periodic fluctuations, attenuating SST-driven growth patterns. We find that seaweed harvesting induces short-term phytoplankton growth. Seaweed farming enhances the teleconnection between phytoplankton and ENSO, but its regulation of phytoplankton mitigates the stimulation of phytoplankton blooms by increased SST, allowing them to exhibit a more regular and stable SST-driven pattern. These findings suggest that moderately expanded seaweed farming can be a scalable, nature-based solution for enhancing coastal ecosystem resilience to ENSO.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144524876","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}
Chengyuan Pang, Maxim Nikurashin, Beatriz Peña-Molino, Bernadette M. Sloyan
{"title":"Variability Due To Seasonal Cycle, Eddies, and Tides Enhances Water Mass Transformation in the Indonesian Seas","authors":"Chengyuan Pang, Maxim Nikurashin, Beatriz Peña-Molino, Bernadette M. Sloyan","doi":"10.1029/2024JC022265","DOIUrl":"https://doi.org/10.1029/2024JC022265","url":null,"abstract":"<p>The Indonesian Seas are a region of rich variability across time scales, with strong air-sea fluxes, and intense diapycnal mixing, leading to water mass transformation within the region. However, the rates of transformation, its distribution, and processes driving it remain poorly understood. Using a high-resolution regional ocean model explicitly simulating internal tides and associated mixing we quantify the water mass transformation in the Indonesian Seas and explore the role of air-sea fluxes, mixing, and tides. Our results show that up to 3.3 Sv of thermocline water is formed within the region from the surface (2.1 Sv) and intermediate and deep (1.2 Sv) water masses. 1.3 Sv, or 40%, of the thermocline water formation is associated with the monsoon-driven seasonal cycle. Monsoons drive large variability in the Indonesian Throughflow and the thermocline water volume, resulting in a net eddy volume transport of the thermocline water out of the Indonesian Seas to the Indian Ocean. This transport adds to the thermocline water transport by the mean circulation, with the total transport being balanced by the thermocline water formation within the Indonesian Seas. The water mass transformation within the region is greatly enhanced by tides. In addition to generating mixing that transforms water masses directly, tidal motions lead to cross-isopycnal (diapycnal) eddy heat and salt fluxes, which facilitate the exchange of properties between water masses and, consequently, their transformation. Our results show that variability across time scales enhances water mass transformation within the Indonesian Seas and should be accurately represented in global ocean and climate models.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022265","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519940","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}
Rachel Diamond, Louise C. Sime, David Schroeder, Laura C. Jackson, Paul R. Holland, Eduardo Alastrué de Asenjo, Katinka Bellomo, Gokhan Danabasoglu, Aixue Hu, Johann Jungclaus, Marisa Montoya, Virna L. Meccia, Oleg A. Saenko, Didier Swingedouw
{"title":"A Weakened AMOC Could Cause Southern Ocean Temperature and Sea-Ice Change on Multidecadal Timescales","authors":"Rachel Diamond, Louise C. Sime, David Schroeder, Laura C. Jackson, Paul R. Holland, Eduardo Alastrué de Asenjo, Katinka Bellomo, Gokhan Danabasoglu, Aixue Hu, Johann Jungclaus, Marisa Montoya, Virna L. Meccia, Oleg A. Saenko, Didier Swingedouw","doi":"10.1029/2024JC022027","DOIUrl":"https://doi.org/10.1029/2024JC022027","url":null,"abstract":"<p>We present the first CMIP6-era multi-model intercomparison of the Southern Ocean (SO) temperature and sea-ice response to substantial Atlantic meridional overturning circulation (AMOC) weakening. Results are based on analysis of the North Atlantic Hosing Model Intercomparison Project, involving eight CMIP6 models under identical North Atlantic freshwater hosing. On multidecadal timescales, we find that southwards ocean heat transport into the SO increases, causing surface warming and sea-ice loss. Additionally, an atmospheric tropical-Antarctic teleconnection, identified here for the first time, causes regional temperature and sea-ice changes in the SO. Unlike previous studies, we find that the Amundsen Sea Low deepens for only some models. Overall, in the multi-model ensemble mean (multi-model range in brackets), over years 50–100 after AMOC weakening: SO surface air temperature warms by 0.3 (0.1–0.7)°C, sea level pressure (SLP) decreases by 30 (10–70) Pa, and sea-ice area decreases by 0.4 (−0.2–1.3) Mkm<sup>2</sup>. The teleconnection leads to regional differences between the response in the Indian sector and the Weddell Sea of 180 (80–320) Pa in SLP, 0.6 (0.5–1.4)°C in surface air temperature, and 0.1 (0.1–0.2) Mkm<sup>2</sup> in sea-ice area. These SO heat transport, temperature, pressure, and sea-ice changes are small relative to the changes expected under future anthropogenic warming, despite the large and idealized 0.3 Sv hosing used to weaken the AMOC.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519942","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}
T. M. Shaun Johnston, Anna Lina P. Sjur, Pål Erik Isachsen, J. H. LaCasce
{"title":"Eddy- and Wind-Driven Circulation in the Enclosed Basins of the Norwegian Sea Evaluated Using a Model and Absolute Geostrophic Flow From Argo","authors":"T. M. Shaun Johnston, Anna Lina P. Sjur, Pål Erik Isachsen, J. H. LaCasce","doi":"10.1029/2024JC021990","DOIUrl":"https://doi.org/10.1029/2024JC021990","url":null,"abstract":"<p>Cyclonic flow in enclosed basins arises from cyclonic vorticity input from either winds or eddies. Previous observations show winds account for about half of the circulation (integral of parallel velocity around a closed isobath) in the Lofoten Basin of the Norwegian Sea, implying a comparable contribution from eddies. In contrast, in the Norwegian Basin, winds explain much of the circulation. We use Argo data from 2012 to 2022, a linear wind-forced and bottom friction-regulated model, and a primitive equation model to investigate how winds and eddies drive the circulation. While Argo cannot resolve individual eddies, it does resolve mesoscale spatial variability. Absolute geostrophic velocities to 2,000 m are calculated by referencing geostrophic shear from objective maps of the profile data to the trajectories at 1,000 m. The time-mean shear is anticyclonic. However, the flow is mostly cyclonic, bottom-intensified, and isobath following. The linear model explains less than half of the observed circulation, suggesting a contribution from an unobserved eddy flux. This interpretation is supported by a numerical model with 800-m horizontal resolution, which resolves the 10–15-km deformation radius. In this model, the difference between the full and linear response comes from an eddy-driven vorticity flux, which produces a largely cyclonic circulation. This result is consistent with the observed global prevalence of positive topostrophy (anticyclonic flow around elevations and cyclonic flow around basins). The observations also show a seasonal shift in the eddy flux, which maybe related to a decadal-scale fresh inflow that alters the density gradient and influences eddy production.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 7","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519691","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}