Journal of Geophysical Research-Oceans最新文献

{"title":"Barotropic Trends Through the Barents Sea Opening for the Period 1975–2021","authors":"Vahidreza Jahanmard,&nbsp;Ulrike Löptien,&nbsp;Anne Britt Sandø,&nbsp;Andrea M. U. Gierisch,&nbsp;Heiner Dietze,&nbsp;Vidar Lien,&nbsp;Nicole Delpeche-Ellmann,&nbsp;Robinson Hordoir","doi":"10.1029/2024JC021663","DOIUrl":"https://doi.org/10.1029/2024JC021663","url":null,"abstract":"<p>We analyze the output of a regional ocean model that comprises the North Atlantic and the Arctic Ocean for the period 1975–2021. We focus on the flow through the cross sections closing the Nordic Sea basin. The simulated flow at Barents Sea Opening (BSO) shows a clear positive trend. To understand the origin of this trend, we reconstruct the BSO flow based on wind time series over the Nordic Seas using deep learning. To explore potential links between the results from this reconstruction and the major atmospheric modes, we perform a suite of idealized experiments where the ocean model is forced with wind field anomalies that refer to known changes in the leading modes of atmospheric circulation over the North Atlantic and Arctic Oceans. Known changes in the major atmospheric wind patterns over the North Atlantic have a weak impact on the simulated BSO flow, and the sign is not consistent with the overall trend of the full simulation. The latter holds as well for the known temporal changes in the intensity of the Arctic dipole mode. The weak temporal changes in the Arctic oscillation are consistent with the trend in the BSO flow but could not explain its amplitude. Ultimately, we could not establish a clear link between the BSO flow trend and changes in the major atmospheric modes. We conclude that the atmospheric pattern responsible for the BSO flow trend does not project directly on the leading modes of atmospheric variability over the North Atlantic and the Arctic.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021663","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143111361","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":"Circulation and Cross-Shelf Exchanges in the Agulhas Bank Region","authors":"R. P. Matano,&nbsp;V. Combes,&nbsp;E. D. Palma,&nbsp;P. T. Strub","doi":"10.1029/2023JC020234","DOIUrl":"https://doi.org/10.1029/2023JC020234","url":null,"abstract":"<p>This modeling study analyzes the circulation over the Agulhas Bank (AB). It is suggested that the time mean circulation over the bank is primarily driven by the inflow of shelf waters from the northeastern region, and not by local forcing as previously postulated. Seasonal variations of the circulation and temperature and salinity fields are highly correlated with the atmospheric forcing. Currents shift inshore during the winter, returning to its original position during summer. The equatorward flow in the western AB, which includes a deep, previously unreported, countercurrent, strengthens during spring and summer and wanes during fall and winter. Tracer diagnostics and Eulerian mass balances reveal very energetics mass exchanges between the eastern AB and the Agulhas Current (AC). The AB Bight is the preferential site for these exchanges. Lagrangian diagnostic show 0.45 Sv of deep open-ocean waters entrained into the bottom layer of the shelf. Cross-shelf exchanges produce significant water mass transformations. Tides play an unexpectedly significant role on the AB circulation. Preliminary considerations suggest that shelf/open-ocean interactions could have a significant impact on water mass conversions within the AC.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2023JC020234","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143111447","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":"Temporal Dynamics of Open Ocean Polynyas Influenced by Sea Ice and Climatic Impacts in the West Cosmonaut Sea","authors":"Guanghua Hao,&nbsp;Hui Shen,&nbsp;Anliang Wang,&nbsp;Yongming Sun","doi":"10.1029/2024JC021815","DOIUrl":"https://doi.org/10.1029/2024JC021815","url":null,"abstract":"<p>Open ocean polynyas, regions of open water surrounded by sea ice, frequently occur in the West Cosmonaut Sea, an Antarctic marginal sea in the southern Indian Ocean sector. These polynyas play a crucial role in regional energy exchange and influence Antarctic atmospheric processes. This study examines the spatial and temporal distribution of the West Cosmonaut Sea polynyas (WCP) from 1979 to 2023, using sea ice concentration (SIC) data collected from May to August. Our results reveal that a pronounced winter sea ice decline promotes the embayment shape formation, precursor to WCP with open water encircled on three sides by sea ice, mainly open on the northeast side. Statistical analysis identifies regions between 62.0–67°S and 28.0–50.0°E, centered near 65°S, 41°E, as hotspots of polynya occurrence. The annual mean WCP area ranges from 2.0 × 10³ to 0.7 × 10⁵ km², with maximum yearly extents between 3.6 × 10³ to 1.5 × 10⁵ km². The yearly accumulated lasting time spans 3–20 days, exhibiting interannual variability with periodicities of 2–3 years and 4–8 years, partially modulated by the Southern Annular Mode. Since 1987, the duration of WCP events has markedly increased, though a decline has been observed since 2012, likely linked to variations in SIC within the embayment. Enhanced wind stress curl supports WCP formation, increases precipitation, and contributes to polynya closure. WCP dynamics amplify evaporation, latent and sensible heat flux, further highlighting the complex interplay between the atmosphere and the ocean in the Antarctic.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143111464","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":"Cross-Shore Sediment Transport on an Open Tidal Flat: Wind-Driven Flow Reversal and Fluid Mud","authors":"Yun Peng,&nbsp;Qian Yu,&nbsp;Aijun Wang,&nbsp;Jianhua Gao,&nbsp;Yunwei Wang,&nbsp;Shu Gao","doi":"10.1029/2024JC022043","DOIUrl":"https://doi.org/10.1029/2024JC022043","url":null,"abstract":"<p>Understanding sediment transport processes within tidal flats is crucial for developing effective land-ocean interaction management strategies. The cross-shore sediment transport on tidal flats induced by episodic events, such as wind-driven flow reversal (WDFR) and fluid mud (FM), is not sufficiently understood. This study focuses on the central Jiangsu tidal flat, where two field campaigns were conducted in the winter of 2021 and the summer of 2022. During the winter campaign, WDFR events were identified. During WDFR, the wind reversed the tide flow direction, resulting in significant cross-shore sediment fluxes. In summer, FM occurred frequently during tidal slack periods when current-induced bottom stress was low. The settling of sediment from the overlying fluid into the bottom layer plays a pivotal role in initiating FM events. These events resulted in substantial cross-shore sediment fluxes, exceeding the long-shore component. This study highlights the need to appropriately address the contributions of WDFR and FM to cross-shore sediment transport in similar coastal environments.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110534","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":"Interactions Between Diurnal Warm Layers and Surface-Layer Fronts","authors":"Jen-Ping Peng,&nbsp;Nicole L. Jones,&nbsp;Matthew D. Rayson,&nbsp;Mira Schmitt,&nbsp;Lars Umlauf,&nbsp;Christopher Whitwell,&nbsp;Shane R. Keating,&nbsp;Callum J. Shakespeare,&nbsp;Gregory N. Ivey","doi":"10.1029/2024JC021380","DOIUrl":"https://doi.org/10.1029/2024JC021380","url":null,"abstract":"<p>Previous studies have highlighted the individual importance of diurnal warm layers (DWLs) and surface-layer fronts within the surface boundary layer (SBL) in regulating energy, momentum, and gas exchange between the atmosphere and the ocean. This study investigates the interactions between DWLs and surface-layer fronts using field observations and numerical turbulence models. Our study provides the real-ocean relevance of the coexistence of DWLs and surface-layer fronts in the SBL in an eddy-rich tropical ocean subjected to intense solar heating and weak winds. We found that the presence of a DWL isolates the deeper layers of the SBL from diabatic and frictional surface forcing, causing these layers to quickly become non-turbulent whereas remaining in a state of marginal stability. This condition suggests that small perturbations from local processes, such as internal tides and waves, can easily trigger instability and turbulence. Additionally, frontal dynamics were observed to deepen the SBL, allowing near-surface diurnal shear associated with DWL dynamics to penetrate to greater depths during nighttime, compared to conditions without a front, thereby facilitating the vertical transport of heat and tracers. Our findings underscore the necessity of accurately representing the interactions between DWLs and surface-layer fronts to enhance the precision of ocean circulation and climate models.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021380","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143110533","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":"Adaptive Process of Bottom-Trapped Buoyant Coastal Current When Encountering a Protruding Coastal Headland","authors":"Silu Zhou,&nbsp;Hui Wu","doi":"10.1029/2024JC021741","DOIUrl":"https://doi.org/10.1029/2024JC021741","url":null,"abstract":"<p>Coastal current encountering a protruding headland is a ubiquitous phenomenon. Previous studies indicated that the coastal current either moves well around headland or separates offshore, leaving the upstream region unaffected. Yet, these studies often assumed a deep vertical coastal wall, and the coastal current was either of barotropic character or surface-advected, with weak interactions with the sloping topography. Here in this study, we conducted numerical experiments to investigate how a protruding headland regulates the “bottom-trapped” buoyant coastal current over a sloping coastal topography. It was found that at the initial stage, the coastal current separates at the sharp headland tip due to local increased centrifugal force, forming a secondary bulge on the lee side of the headland. Upstream of the headland, a countercurrent is formed shoreward of the front, which fills the space between front and coast, thus pushing the front offshore. This process persists as long as the cross-shelf scale of headland is larger than the baroclinic Rossby deformation radius. The final effect is that the front adapts its cross-shelf location to minimize the form drag induced by the headland, and consequently the separation on the lee side of the headland was reduced. Downstream of the headland, the plume front weakens and the alongshore propagation is slowed down, because more freshwater is stranded upstream. Such dynamics are distinct from the surface-advected buoyant coastal current, and may explain the fact that many buoyant coastal currents along zigzag coastline are wide and their alongshore extension distances are limited.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143119828","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":"Drivers of Nickel Distribution and Seasonality in the Southern Ocean: New Perspectives From the GEOTRACES GIpr07 Transect","authors":"R. Cloete,&nbsp;H. Planquette,&nbsp;N. R. van Horsten,&nbsp;S. Samanta,&nbsp;X.-G. Chen,&nbsp;E. P. Achterberg,&nbsp;R. Middag,&nbsp;D. J. Janssen,&nbsp;A. R. Bowie,&nbsp;P. van der Merwe,&nbsp;J. C. Loock,&nbsp;T. N. Mtshali,&nbsp;S. Fietz,&nbsp;A. N. Roychoudhury","doi":"10.1029/2024JC021542","DOIUrl":"https://doi.org/10.1029/2024JC021542","url":null,"abstract":"<p>Winter dissolved nickel (dNi) and particulate nickel (pNi) concentrations were measured in the Southern Ocean (GEOTRACES GIpr07 transect) to investigate biogeochemical cycling within the water column and over seasonal timescales. Concentrations of dNi ranged from 1.98 to 8.21 nmol kg⁻¹ with low surface concentrations and maxima in deepest sampled water masses. Combining our winter data with the GEOTRACES Intermediate Data Product (2021) shows insignificant seasonal dNi variation in surface waters north of the Antarctic Polar Front, indicating the dominance of year-round mixing processes. However, lower summer concentrations than winter in the Antarctic Zone (∆0.23 nmol kg⁻¹) suggest a role for biological processes at high latitudes. For pNi, concentrations ranged from 5 to 49 pmol kg⁻¹ with higher values in surface/near-surface water masses. Vertical attenuation factors (<i>b</i> values) for pNi (0.19 ± 0.06) and particulate phosphorus (pP; 0.43 ± 0.10) suggest a greater retention of Ni in particles than P, invoking scavenging processes or refractory Ni phases. Water mass analysis shows that remineralization of pNi contributes a maximum of 6% of the highest measured dNi. Instead, dNi distributions and macronutrient relationships were largely explained by phytoplankton uptake in surface waters, and mixing and advection of Atlantic and Antarctic origin water masses, each with different preformed nutrient compositions. Winter trace metal measurements provide new perspectives regarding the balance between biological and physical drivers in the Southern Ocean. For Ni, the biological component is small with respect to physical mixing processes and over the timescales in which water masses accumulate Ni during their transport.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021542","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143119829","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":"Observations of Estuarine Salt Intrusion Dynamics During a Prolonged Drought Event in the Rhine-Meuse Delta","authors":"Tess M. Wegman,&nbsp;Julie D. Pietrzak,&nbsp;Alexander R. Horner-Devine,&nbsp;Henk A. Dijkstra,&nbsp;David K. Ralston","doi":"10.1029/2024JC021655","DOIUrl":"https://doi.org/10.1029/2024JC021655","url":null,"abstract":"<p>Salt intrusion poses a global threat to estuaries and deltas, exacerbated by climate change, drought, and sea level rise. This observational study investigates the impact of river discharge, wind, and tidal variations on salt intrusion in a branching river delta during drought. The complexity and spatial extent of deltas make comprehensive measurements challenging and rare. In this paper, we present a 17-week data set of a historic drought in the Rhine-Meuse Delta, capturing dynamics in a multiple-channel system in a wide range of conditions. Key characteristics of this low-lying delta are its branching channel network and complicated, human-controlled discharge. Despite the system's complexity, we found that the subtidal salt intrusion length, defined by the 2 PSU isohaline <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left({L}_{2}right)$</annotation>\u0000 </semantics></math>, follows a power law relationship with Rhine River discharge <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mfenced>\u0000 <mrow>\u0000 <msub>\u0000 <mi>L</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 <mo>∝</mo>\u0000 <msubsup>\u0000 <mi>Q</mi>\u0000 <mi>R</mi>\u0000 <mrow>\u0000 <mo>−</mo>\u0000 <mn>0.35</mn>\u0000 <mo>±</mo>\u0000 <mn>0.03</mn>\u0000 </mrow>\u0000 </msubsup>\u0000 </mrow>\u0000 </mfenced>\u0000 </mrow>\u0000 <annotation> $left({L}_{2}propto {Q}_{R}^{-0.35pm 0.03}right)$</annotation>\u0000 </semantics></math>. Subtidal water level variations contribute to short-term variations in intrusion length, shifting the limit of salt intrusion upstream and downstream with a distance similar to the tidal excursion length. This can be attributed to the up-estuary transport of seawater, caused by the estuary adjusting to variations in water levels at its mouth. However, spring-neap variation in the tidal range does not alter the subtidal salt intrusion length. Side branches exhibit distinct dynamics from the main river, and their most important control is the downstream salinity. We show that treating the side branches separately is crucial to incorporate the highly variable downstream boundary condition, and may apply in other deltas or complex estuaries.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 1","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021655","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143119260","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 Ocean Model Horizontal Resolution on the Representation of Global Annual-To-Multidecadal Coastal Sea Level Variability","authors":"Christopher M. Little,&nbsp;Stephen G. Yeager,&nbsp;Rui M. Ponte,&nbsp;Ping Chang,&nbsp;Who M. Kim","doi":"10.1029/2024JC021679","DOIUrl":"https://doi.org/10.1029/2024JC021679","url":null,"abstract":"<p>Emerging high-resolution global ocean climate models are expected to improve both hindcasts and forecasts of coastal sea level variability by better resolving ocean turbulence and other small-scale phenomena. To examine this hypothesis, we compare annual to multidecadal coastal sea level variability over the 1993–2018 period, as observed by tide gauges and as simulated by two identically forced ocean models, at <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>1</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${sim} 1{}^{circ}$</annotation>\u0000 </semantics></math> (LR) and <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>0.1</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${sim} 0.1{}^{circ}$</annotation>\u0000 </semantics></math> (HR) horizontal resolution. Differences between HR and LR, and misfits with tide gauges, are spatially coherent at regional alongcoast scales. Resolution-related improvements are largest in, and near, marginal seas. Near attached western boundary currents, sea level variance is several times greater in HR than LR, but correlations with observations may be reduced, due to intrinsic ocean variability. Globally, in HR simulations, intrinsic variability comprises from zero to over 80% of coastal sea level variance. Outside of eddy-rich regions, simulated coastal sea level variability is generally damped relative to observations. We hypothesize that weak coastal variability is related to large-scale, remotely forced, variability; in both HR and LR, tropical sea level variance is underestimated by <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 </mrow>\u0000 <annotation> ${sim} $</annotation>\u0000 </semantics></math>50% relative to satellite altimetric observations. Similar coastal dynamical regimes (e.g., attached western boundary currents) exhibit a consistent sensitivity to horizontal resolution, suggesting that these findings are generalizable to regions with limited coastal observations.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"129 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118282","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":"Comparison of the ENSO-Related Interannual Variability of the ECS-Kuroshio Before and After 2005","authors":"Zhao-Jun Liu,&nbsp;Yu-Xiang Qiao,&nbsp;Hirohiko Nakamura,&nbsp;Xiao-Hua Zhu,&nbsp;Ayako Nishina,&nbsp;Chuanzheng Zhang,&nbsp;Ze-Nan Zhu,&nbsp;Cong Xiao","doi":"10.1029/2024JC021242","DOIUrl":"https://doi.org/10.1029/2024JC021242","url":null,"abstract":"<p>The El Niño-Southern Oscillation (ENSO)-related interannual variability of the Kuroshio in the East China Sea (ECS) was revisited based on reanalysis outputs during 1993–2018. Unlike the synchronized variations from 2006 to 2018, the period of 1993–2005 showed regional differences in how the ECS-Kuroshio responded to ENSO events. Specifically, from the upstream region to the midway of the continental slope, the ECS-Kuroshio exhibited distinct six-year interannual modulation during 1993–2005. In contrast, downstream Kuroshio variability primarily followed a four-year cycle, aligning with ENSO variability during the same period. Further analysis suggested that the sea surface height anomaly (SSHA) east of the Kerama Gap, near the midpoint of the Ryukyu Island chain, extended inside the ECS until the southern side of the Tokara Strait along the ECS-Kuroshio path and was well correlated with the Kuroshio in the Tokara Strait during 1993–2005. The cause of this SSHA signal was attributed to forcing by ENSO-related wind stress curl changes in the interior region. There was an obvious difference in the ENSO-related atmospheric circulation before and after 2005. The wind stress curl pattern in the North Pacific during 1993–2005, characterized by a maximum in the Kerama Gap latitude band, shifted northward compared to that during 2006–2018. The relative northward shift of the ENSO-related wind stress curl, which stimulates the long baroclinic Rossby wave propagating westward and arriving east of the Kerama Gap, affect the interannual variabilities of both the upstream and downstream Kuroshio.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"129 12","pages":""},"PeriodicalIF":3.3,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143118163","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}