Journal of Geophysical Research-Oceans最新文献

{"title":"Satellite-Based Retrieval of the Vertical Structure of Internal Solitary Waves in Continuous Stratification","authors":"Xixi Li,&nbsp;Jianjun Liang,&nbsp;Xiao-Ming Li","doi":"10.1029/2024JC022180","DOIUrl":"https://doi.org/10.1029/2024JC022180","url":null,"abstract":"<p>The vertical structure of internal solitary waves (ISWs), defined by the amplitudes at different water depths, is critical for understanding and predicting how the waves affect ocean mixing and sediment transport. Spaceborne synthetic aperture radar (SAR) data have been used to retrieve the vertical structures of ISWs in many parts of the global oceans. However, the commonly used theories for determining the vertical structure from SAR images are often based on a two-layer ocean model, deviating from the continuous stratification found in the real ocean environment. In this study, we retrieved the vertical structures of ISWs in continuous stratification from SAR images through a machine learning approach. We first proposed an improved parameterization scheme for ocean stratification incorporating a component of deep-layer stratification. With this scheme, we simulated the vertical structures of ISWs and their corresponding radar surface signatures. These physical simulations lead to a key input, the modulation depth, excluded in existing methods or models. Then, the relationship between radar signals and vertical structures of ISWs was found through a backpropagation neural network. We validated the relationship by two contemporaneous experiments conducted in the Andaman Sea and the Strait of Gibraltar. This study aims to provide a fresh perspective on retrieving the vertical structure of ISWs in the real ocean environment by replacing the ideal two-layer ocean model and demonstrates the applicable potential of satellites in retrieving three-dimensional structures.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143840779","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":"The Spatial and Temporal Variations in Tritium in the North Pacific Over the Past 70 Years and Their Impacts on the Marine Environment and Organisms","authors":"Zhenxin Yu,&nbsp;Zichun Shen,&nbsp;Zhizhou Shi,&nbsp;Wen Fang,&nbsp;Xiaoqing Liu,&nbsp;Wen Yu,&nbsp;Minggang Cai","doi":"10.1029/2024JC022058","DOIUrl":"https://doi.org/10.1029/2024JC022058","url":null,"abstract":"<p>To better understand the fate of treated water from the Fukushima Daiichi Nuclear Power Plant (FDNPP) and its potential impacts, this study gathered data regarding tritium in the North Pacific from the past 70 years using field surveys and published literature. With these data, we explore the spatiotemporal distribution patterns of tritium in the North Pacific and the underlying mechanisms of the spatiotemporal patterns. We also discuss the impacts of treated water discharge on marine tritium levels and radiological doses with respect to marine life. The main results include the following: (a) From the 1950s until 2011 (pre-Fukushima), the tritium concentration in the North Pacific declined exponentially, with an effective half-life of 10.66 years. (b) The impact of the FDNPP accident was most pronounced in Fukushima coastal waters, where the average tritium concentration increased 30-fold between 2011 and 2024. (c) From August 2023 to October 2024, the average tritium concentration within 0–1.5 km of Fukushima decreased by 39.1%. (d) During the same period, the tritium concentration increased between 1.5 and 30 km from Fukushima, and the average tritium concentration within this same range from Fukushima increased most significantly from 111.5 ± 91.1 Bq/m³ to approximately 513.2 ± 812.5 Bq/m³. It is predicted that the concentration within the 1.5–3-km range from Fukushima will exhibit a cyclical pattern due to periodic discharges over the next 30–40 years. (e) Current tritium concentrations in local marine waters remain within the safety limits established by internationally recognized standards.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831061","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":"Responses of Nutrient Biogeochemistry to a Mesoscale Eddy Detached From the Kuroshio Loop Current","authors":"Nan Zhou,&nbsp;Sumei Liu,&nbsp;Jingling Ren,&nbsp;Ying Wu,&nbsp;Lei Li,&nbsp;Jun Wang,&nbsp;Xiaoyan Ning","doi":"10.1029/2024JC021792","DOIUrl":"https://doi.org/10.1029/2024JC021792","url":null,"abstract":"<p>Mesoscale eddies play important roles in ocean biogeochemical cycles by enhancing lateral and vertical transport of materials and energy. We investigated the nutrient biogeochemistry, including the nitrogen cycle, in the northern South China Sea (NSCS) under the influence of an anticyclonic mesoscale eddy detached from the Kuroshio loop current (KLC). The detached eddy transported substantial amounts of water and nutrients that originated from the Kuroshio to the southwest hinterland of the NSCS. Using a nitrogen mass and isotope balance model, we estimated that the enhanced particulate nitrogen flux exported from the euphotic zone at the eddy center area was 2.4 ± 1.7 times that in background area. In addition, the nitrogen fixation and atmospheric depositions (NFAD) nitrogen flux was estimated to be 0.18 ± 0.15 mmol m⁻² d⁻¹. The average proportion of new production sustained by NFAD nitrogen relative to dissolved inorganic nitrogen (DIN) supplied from below was 12%, and the turnover time of DIN in the euphotic zone within the eddy was estimated to be ∼9 days. The eddy-trapped Kuroshio water influenced the distribution of nutrients and nitrate isotope composition above 400-m depth in the NSCS. The remineralization of newly fixed nitrogen originating from NFAD and the subsequent nitrification regulated nitrate isotope composition above 800 m, whereas assimilation also played a role within the euphotic zone. Deep-water communication with the North Pacific and the input of the North Pacific Intermediate Water introduced the denitrification signal that originated from the eastern tropical North Pacific into the NSCS.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830988","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":"Branching of Antarctic Bottom Water Flow in the Middle Part of the Vema Channel Revealed by Direct Velocity Measurements","authors":"D. I. Frey","doi":"10.1029/2024JC021580","DOIUrl":"https://doi.org/10.1029/2024JC021580","url":null,"abstract":"<p>The Antarctic Bottom Water flow in the Vema Channel of the Southwest Atlantic is one of the strongest abyssal flows in the World Ocean. The spatial structure of abyssal waters in the channel has been previously studied by different authors only at two locations: at the Vema Sill in the southern part of the channel and at the Vema Extension in its northern part. Here we report new measurements that reveal an additional, shallower branch of the current in its middle part. These new observations show that two individual current branches are observed in the middle, previously unexplored part of the Vema Channel at approximately 28°S. Repeated measurements have also revealed strong simultaneous variations in thermohaline properties and bottom current direction in the shallower branch, indicating that abyssal waters transported to the south differ from those transported to the north due to differences in mixing between water masses in the channel. The new temperature observations show almost the same mean warming rates in different regions of the Vema Channel varying from 1.8 to 2.4 mK/year during the last two decades. New observations show that both studied branches transport the Antarctic Bottom Water between the Argentine and Brazil basins; moreover, the additional shallow branch changes its direction and the transport here can be directed both northward and southward.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826812","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":"Imaging Thermocline Microstructure in 2D With Swaths Traced by Wave-Pumped \u0000 \u0000 \u0000 χ\u0000 \u0000 $chi $\u0000 pods","authors":"Kenneth G. Hughes,&nbsp;James N. Moum","doi":"10.1029/2024JC022134","DOIUrl":"https://doi.org/10.1029/2024JC022134","url":null,"abstract":"&lt;p&gt;Quasi two-dimensional visualizations of microstructure in the thermocline are created by processing &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;χ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $chi $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;pod signals in a nonstandard way. As the moored instrument is pumped by surface waves, the fast thermistors at each end trace out vertically overlapping paths, from which we produce 2–3 m tall swaths. A swath capturing the unmistakable form of Kelvin–Helmholtz billows provides a proof of concept—albeit by relying on what is a rare event in our data set in which the flow is generally stable (as per the Richardson number). More commonly, swaths exhibit steppy temperature fields during weaker turbulence, an abundance of small overturns during stronger turbulence, or some combination thereof. To examine this continuum statistically, we take a 13-month data set from an equatorial &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;χ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $chi $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;pod at a 120-m depth and divide it into 53,000 swaths, each 10-min long. Swaths are ordered based on their associated buoyancy Reynolds number &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mfenced&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;/mfenced&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $left(mathrm{R}{mathrm{e}}_{mathrm{b}}right)$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; inferred from our standard &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;χ&lt;/mi&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $chi $&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;pod processing. Clear visual differences in swath characteristics arise when comparing across an order of magnitude or more (e.g., &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;&lt;&lt;/mo&gt;\u0000 &lt;mn&gt;10&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; $mathrm{R}{mathrm{e}}_{mathrm{b}}&lt; 10$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; vs. &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mi&gt;R&lt;/mi&gt;\u0000 &lt;msub&gt;\u0000 &lt;mi&gt;e&lt;/mi&gt;\u0000 &lt;mi&gt;b&lt;/mi&gt;\u0000 &lt;/msub&gt;\u0000 &lt;mo&gt;=&lt;/mo&gt;\u0000 ","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022134","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143831062","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":"Cold Spells, Fresh Waves, and the Biogeochemical Response in the North Atlantic Cold Anomaly Region","authors":"Fatma Jebri,&nbsp;Zoe L. Jacobs,&nbsp;Meric Srokosz,&nbsp;Ekaterina Popova,&nbsp;Susan E. Hartman,&nbsp;Simon A. Josey","doi":"10.1029/2024JC022001","DOIUrl":"https://doi.org/10.1029/2024JC022001","url":null,"abstract":"<p>Regional effects of marine cold spells (MCS, periods of anomalous cooling), their impact on ecosystem biogeochemistry, and link to salinity extremes remain underexplored. A case in point is North Atlantic's Cold Anomaly (CA) region (known as the “cold blob”), which hits record low temperatures during 2014–16 while most of the global ocean warmed. Using up to 42 years of observations, we characterize the CA as a manifestation of both MCS and Fresh Waves (FW, low salinity extremes) and analyze the surface biogeochemical response. We observe a quasiperiodic pattern of MCS from the 1980s and FW (at least) from the 1990s to early 2020s in the CA region with alternations from cool and freshwater to warm and saline conditions. Since 1990s, the CA region appears to be potentially undergoing MCS and FW compound events that are more frequent and prolonged but less intense than other North Atlantic areas. The 2014-16 CA was among the most widespread and prolonged MCS and FW events associated with a deeper mixed layer and distinct biogeochemical signature, including elevated nutrients and oxygen, an overall increased chlorophyll-a and intensified ocean acidification. These results suggest that MCS could mitigate certain climate change effects through cooling and enhanced productivity, while exacerbating others such as ocean acidification. We compare 2014–16 CA region effects with those of Pacific's warm blob, identifying contrasting behaviors from physical processes to biogeochemical impacts and discussing a common atmospheric driver. Our findings emphasize the need to further study ecological responses to MCS in the North Atlantic.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822088","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":"Mooring-Observed Cross Equator Propagation of Kelvin Waves Through the Makassar Strait","authors":"Tengfei Xu,&nbsp;Shujiang Li,&nbsp;Yingyi Yang,&nbsp;Yaohua Zhu,&nbsp;A. Kuswardani,&nbsp;Yonggang Wang,&nbsp;Guanlin Wang,&nbsp;Xiaoqing Xu,&nbsp;Fei Teng,&nbsp;Agus Setiawan,&nbsp;Priyadi Dwi Santoso,&nbsp;Teguh Agustiadi,&nbsp;Mukti Trenggono,&nbsp;R. Dwi Susanto,&nbsp;Zexun Wei","doi":"10.1029/2024JC022310","DOIUrl":"https://doi.org/10.1029/2024JC022310","url":null,"abstract":"<p>The propagation of intraseasonal Kelvin waves in the Indonesian seas significantly modulates the Indonesian Throughflow (ITF) transport. However, their northward propagation across the equator within the main ITF route, particularly through the Makassar Strait, has remained unverified due to a lack of in situ observations. This study presents simultaneous mooring observations of current velocity profiles at the choke points in the ITF's main pathway, from the Lombok Strait to the northern Makassar Strait. Our results confirm the propagation of intraseasonal Kelvin waves cross the equator reaching the northern Makassar Strait, primarily along the 100-m isobath. During the propagation, the dominant modes are the first and second baroclinic modes in the Indian Ocean, the second and third baroclinic modes between the Lombok and southern Makassar Straits, and the third to fifth baroclinic modes between the southern and northern Makassar Straits. Vertical mode decomposition reveals that the intraseasonal velocity anomaly in the northern Makassar Strait comprises the first five baroclinic modes, with the first two modes dominant in the upper 400 m and the third to fifth modes dominant at depths of 400–800 m. Our finding establishes the Makassar Strait as a definite pathway for the cross-equator propagation of Kelvin waves, linking wave dynamics between the Pacific and Indian Oceans.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822117","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":"Comparing the Role of Floe Breakage and Melt on Summer Sea Ice Loss","authors":"Rigoberto Moncada,&nbsp;Mukund Gupta,&nbsp;Andrew F. Thompson,&nbsp;Jose E. Andrade","doi":"10.1029/2024JC021223","DOIUrl":"https://doi.org/10.1029/2024JC021223","url":null,"abstract":"<p>Marginal ice zones are composed of individual sea ice floes, whose breakage and melt influence its dynamical behavior. These processes are not well represented by global or regional climate models due to the continuum approximations and uncertainties regarding forcing, data resolution and parameterizations used for sea ice. Here, we use a Discrete Element Model (DEM) coupled to a slab thermodynamic ocean to investigate how breakage and melt processes impact the decay of summer sea ice. The DEM is calibrated using MODIS satellite imagery and reanalysis data within the Arctic Ocean's Baffin Bay during June–July 2018. The sensitivity of the sea ice decay is evaluated by varying the solar heating, the ice/ocean heat exchange parameter, and a prescribed floe breakage rate. For the parameter regime that best fits observations, the ratio of mass loss of resolved floes (diameter <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 <annotation> ${ &gt;} $</annotation>\u0000 </semantics></math>2 km) due to breakage versus melt is 0.47, and oceanic versus solar melt is 0.46. The rate at which resolved floes lose mass is most sensitive to the breakage rate, as compared to the solar and oceanic melt parameters. The number decay of the largest floes (<i>D</i> <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&gt;</mo>\u0000 </mrow>\u0000 <annotation> ${ &gt;} $</annotation>\u0000 </semantics></math>21 km) is controlled by breakage, whereas the decay of smaller floes (<i>D</i> = 2–21 km) depends strongly on lateral and basal melt. Inferences from this exploration of the parameter space may help motivate more accurate parameterizations of the floe size distribution evolution in climate models.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143822316","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":"Role of Midwater Mixed Waves in the Loop Current Separation Events From a Coupled Ocean-Atmosphere Regional Model and In Situ Observations","authors":"Xiao Ge,&nbsp;Steven F. DiMarco,&nbsp;Yun Liu,&nbsp;Ping Chang,&nbsp;Dan Fu,&nbsp;Jaison Kurian,&nbsp;Chuan-Yuan Hsu,&nbsp;Anthony H. Knap","doi":"10.1029/2024JC021330","DOIUrl":"https://doi.org/10.1029/2024JC021330","url":null,"abstract":"<p>A previously uninvestigated necking-down region in the Gulf of Mexico, associated with the Loop Current eddy (LCE) separations is defined by the 8–16 days variance below the Loop Current system (LCS) around 88.5°W, using an Ocean-Atmosphere Coupled Regional-Community Earth System Model (R-CESM) 9-year nature run, which reveals the mechanisms of Loop Current (LC) deep dynamics. Scaled wavelet analysis of flow fields in five regions at the 27.5 kg/m³ potential density layer under the LCS shows that the 8–16 days variance is reproduced by the R-CESM model dynamics, aligning with in situ observations. This weather band deep variance, identified as the mixed waves located between the mixed Rossby-gravity waves and Rossby waves in the ocean wave dispersion relationship, is stimulated by the interaction between the penetrating LC and steep topography. Then, these waves are released from the constraints of the topography and become free wave trains. There are three critical regions for the propagating wave trains: the Mississippi Fan, the Yucatan Shelf, and the Florida Escapement. The various wave trains define five distinct scenarios: East Yucatan Shelf (EYSS), West Yucatan Shelf (WYSS), west Florida escarpment (WFES), Mississippi Fan (MFS), and quiescent (QS) scenarios. The scenarios passing through the west necking-down region can be used to indicate the LCE separations. After the separations, the retracted LC may encounter interference from either the EYSS or the WFES, preventing the reattachments. These 8–16-day waves offer insights into describing the LC shedding events from the lower layer of the LCS, enhancing the understanding of LCS dynamics.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC021330","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143818372","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":"Weakened Eddy Activities in the South Pacific Subtropical Countercurrents Under Global Warming","authors":"Ningyuan Xiao,&nbsp;Shengpeng Wang,&nbsp;Chen Yang,&nbsp;Fengfei Song,&nbsp;Zhao Jing,&nbsp;Lixin Wu","doi":"10.1029/2024JC022128","DOIUrl":"https://doi.org/10.1029/2024JC022128","url":null,"abstract":"<p>The subtropical countercurrent (STCC), located near the South Pacific boundary, exhibits a band of high eddy activities. These eddies have significant implications on the exchanges of heat, salt, volume, and biogeochemical properties. Yet their response to greenhouse warming change remains unknown. Using an ensemble of long-term high-resolution climate simulations under a high carbon emission, we show that eddy kinetic energy (EKE) in the STCC is projected to be significantly reduced in a warming climate. This reduction primarily stems from weakened baroclinic instability of the STCC-South Equatorial Current (SEC) system, which is associated with a projected decrease in vertical velocity shear and an increase in upper ocean stratification. The former majorly results from an enhanced meridional salinity gradient due to the reduction in subtropical precipitation, whereas the latter is caused by an enhanced thermal stratification associated with a faster surface warming in a warming climate. The findings of this study will contribute to a better understanding of the impact of climate change on ocean motions as well as their climate impact near the western boundary.</p>","PeriodicalId":54340,"journal":{"name":"Journal of Geophysical Research-Oceans","volume":"130 4","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JC022128","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143818431","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}