Deep-Sea Research Part I-Oceanographic Research Papers最新文献

{"title":"Analysis of communities, with an historical reconstruction from a deep submarine seamount in an oligotrophic area (Valencia Seamount, Balearic Basin, Western Mediterranean)","authors":"J.E. Cartes ,&nbsp;V. Papiol ,&nbsp;J. Santos-Echeandía ,&nbsp;D. Díaz-Viñolas ,&nbsp;A. Serrano ,&nbsp;D. Palomino ,&nbsp;J.C. Pintado-Patiño","doi":"10.1016/j.dsr.2024.104325","DOIUrl":"https://doi.org/10.1016/j.dsr.2024.104325","url":null,"abstract":"<div><p>Seamounts can have strong influence on the dynamics and production of waters surrounding them, sometimes creating a kind of <em>oasis</em> effect. To assess to what depths and under what conditions this effect may persist on seamounts, we analysed the fauna and recent history of the Valencia Seamount (VS), a deep, small seamount (summit depth: 1056 m) from an oligotrophic zone of the Mediterranean Sea. The (living) epibenthic fauna of the VS summit (up to 1300 m) was composed of filter feeders, surface deposit feeders and carnivores (63 species), structured in a trophic chain as indicated by the high positive relationship (r² 0.502) between the δN¹⁵and δC¹³ of the fauna analysed. This trophic linearisation (compared with Catalan and NW Mallorca slope sites at similar depths) may optimise the energy flux reaching the seamount, with rather high %TOC (0.93–1.19%) and C/N (5.0–5.5) in July. The Valencia Seamount can also act as a reservoir zone for fish (grenadiers: <em>Nezumia aequalis</em>, and <em>Hymenocephalus italicus</em>) and shrimps (<em>Plesionika martia</em>), which are distributed at shallower depths on adjacent slopes, where they are exploited. The specimens caught were mainly juveniles, suggesting that these species may rather form pseudopopulations. Tuna and cetaceans were regularly sighted on the surface of VS during a specific period of the year (June–July). Reconstructing the recent history of Valencia Seamount (MC2 sediment core taken at 1151 m in 2021) we evidenced a decline of zooplankton pteropods (primary consumers) since <em>ca</em>. the 1960s (MC2 dating after ²¹⁰Pb, metals and microplastic analyses), linked to a decline of Si in sediments suggesting a decrease in primary production due to a decrease in rainfall and river runoff. An increase of vorticity (<em>ω</em>^<em>+</em> values), i.e. of cyclonic gyres, and currents after the 1970s over the summit probably increased resuspension of organic matter, which in turn may enhance zooplankton aggegations at VS summit. We hypothesise that this would explain the parallel increase in mesopelagic myctophids in MC2 (from otolith records). Sediments of the Valencia seamount recorded several historical changes. Reconstruction studies carried out in oceanic areas can therefore help to understand the history and improve the management of fragile systems such as seamounts.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"209 ","pages":"Article 104325"},"PeriodicalIF":2.4,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141292341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Classification of sound speed fields in the Western Pacific Ocean based on tensor decomposition","authors":"Yinglin Chen ,&nbsp;Peng Xiao ,&nbsp;Chunhua Qiu ,&nbsp;Zhenglin Li","doi":"10.1016/j.dsr.2024.104328","DOIUrl":"https://doi.org/10.1016/j.dsr.2024.104328","url":null,"abstract":"<div><p>The three-dimensional (3-D) sound speed structure of the ocean is a fundamental environmental element in studying underwater sound propagation modeling and forecasting. The accurate classification of the sound speed fields (SSFs) provides a comprehensive understanding and analysis of the sound propagation pattern. To take advantage of the 3-D structure of the ocean SSFs, this paper presents a quick method based on tensor decomposition for classifying the ocean 3-D SSFs. Utilizing the WOA18 dataset, High Order Iterative Orthogonal (HOOI) decomposition of the 3-D SSFs is executed so as to accurately extract the characteristic information of the SSFs. The Fuzzy C-Means clustering (FCM) method is applied to classify the feature tensors, partitioning of regional categories in different seasons and revealing the typical SSFs structures. By combining the BELLHOP model with analysis of the characteristics of the first convergence zone of each category, it is concluded that there are six categories of SSFs in the Western Pacific Ocean. The SSFs across all categories are primarily latitudinally distributed, featuring distinct sound channel axes and surface sound speed variations.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"209 ","pages":"Article 104328"},"PeriodicalIF":2.4,"publicationDate":"2024-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141325107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research priorities and roadmap for deep-sea ecology in the Bay of Biscay (Northeast Atlantic)","authors":"Ibon Galparsoro ,&nbsp;Iratxe Menchaca ,&nbsp;Ivan Manso-Narvarte ,&nbsp;Irene Ruiz ,&nbsp;Maria C. Uyarra ,&nbsp;Javier Franco ,&nbsp;Iñigo Muxika ,&nbsp;Miquel Canals ,&nbsp;Alberto Serrano ,&nbsp;José Manuel González-Irusta ,&nbsp;Alberto Abad-Uribarren ,&nbsp;Ana Colaço ,&nbsp;María Gómez-Ballesteros ,&nbsp;Javier Cristobo ,&nbsp;Pilar Ríos ,&nbsp;Fergal McGrath ,&nbsp;Ángel Borja","doi":"10.1016/j.dsr.2024.104324","DOIUrl":"https://doi.org/10.1016/j.dsr.2024.104324","url":null,"abstract":"<div><p>The Bay of Biscay is a structurally complex region, exhibiting high biodiversity and productivity and hosting a wide variety of benthic habitats. Unfortunately, current scientific knowledge of deep-sea ecosystems is limited. Our investigation provides an updated vision of the existing knowledge on key aspects of the deep-sea ecosystem and identifies research priorities for the definition of a research roadmap in support of sustainable management, including the protection and conservation of deep-sea ecosystem of the Bay of Biscay. To achieve this, firstly a revision of projects, surveys and studies conducted in the region, was carried out resulting in the identification of 62 publicly available scientific documents. Secondly, an online survey was carried out, receiving 51 responses from 24 research institutions in 9 countries. Finally, a workshop was attended by 39 scientists to identify and discuss ways forward on deep-sea research in the Bay of Biscay. Results indicate that knowledge of benthic habitats, and vulnerable and sensitive habitats/species is good or very good for 45% of the respondents, while limited knowledge was reported for deep pelagic habitats. Almost 75% of the scientists agreed that deep-sea processes affect shallower areas. Funding (71%) and research vessel availability (57%) were considered the most constraining aspects limiting deep-sea research. More than 50% of the scientists perceived a short- or medium-term threat from human activities and pressures, while over than 40% of the respondents considered that there are no, or limited, data available to assess the environmental status. Regarding climate change, 55% of scientists partially or fully agreed with the existence of evidence of climate change effects, but 47% of them totally or partially considered that climate change monitoring is insufficient to assess eventual changes and effects. Most respondents (63%) considered that deep-sea ecosystems are not properly represented in the current Marine Protected Areas network. In terms of future needs, the development of monitoring strategies to reduce costs and guarantee an optimal design, data sharing and an increase in transnational collaboration are most cited. Finally, a proposal for a roadmap to fill in knowledge gaps for a better understating of the ecosystem processes of the deep sea of the Bay of Biscay is delivered.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104324"},"PeriodicalIF":2.4,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0967063724000943/pdfft?md5=e3a7654ec545f4f0c8cbd35e741f952e&pid=1-s2.0-S0967063724000943-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141090985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Development of a deep-sea in-situ anion analyzer for marine biogeochemical cycle observation","authors":"Chao Chen ,&nbsp;Feng Lyu ,&nbsp;Bangchun Wu ,&nbsp;Zhengwei Wu","doi":"10.1016/j.dsr.2024.104326","DOIUrl":"10.1016/j.dsr.2024.104326","url":null,"abstract":"<div><p>A novel deep-sea <em>in-situ</em> anion analyzer (DIAA) is proposed and developed for long-term and continuous observation of marine biogeochemistry and ecology. The DIAA is designed to analyze the concentrations of various anions in seawater, such as F⁻, Cl⁻, Br⁻, NO₃⁻, SO₄²⁻, and PO₄³⁻, based on ion chromatography (IC) technology. The DIAA consists of a control circuit module, a conductivity signal acquisition module, and a flow analysis module. The control circuit module is installed in a sealed pressure-resistant vessel, while the conductivity signal acquisition module and the flow analysis module are housed in a sealed pressure-balanced vessel. The two vessels are capable of functioning at a water depth of up to 4000 m. A seawater <em>in-situ</em> dilution device is designed to solve the issue that the concentrations of Cl⁻ and SO₄²⁻ in seawater exceeds the IC detection limit. Moreover, an <em>in-situ</em> calibration device enables the DIAA to operate subsea for a long time without recovery. In addition, the DIAA can diagnose and isolate faults automatically. The operation status can be monitored remotely on the shore, and the scientific data can be acquired in real-time. During the sea trial, the DIAA was connected to Monterey Accelerated Research System (MARS) seafloor observatory at a water depth of approximately 900m and operated for six months successfully. The measurement accuracy and the long-term stability of the instrumentation have been verified.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104326"},"PeriodicalIF":2.4,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141137269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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 impact of vertical mixing on the variability of salinity in the Black Sea pycnocline: Role of winter convection, vertical shear and mediterranean waters injections.","authors":"A.A. Kubryakov ,&nbsp;A.G. Zatsepin ,&nbsp;O.S. Puzina ,&nbsp;S.V. Stanichny","doi":"10.1016/j.dsr.2024.104321","DOIUrl":"10.1016/j.dsr.2024.104321","url":null,"abstract":"<div><p>Rapid rise of salinity is observed in the Black Sea in recent years, with the largest positive trend (0.07 psμ per 10 years) detected in the pycnocline. We use long-term hydrological measurements for 1985–2019 to show that salinity of pycnocline has intense seasonal and interannual variability modulated by the mechanical and convective mixing. In the warm period of a year, shear turbulence driven by strong winds and intense geostrophic currents causes the penetration of warm waters into the lower density layers. This is accompanied by the rise in their salinity, the source of which is the deep saline waters situated below the halocline. This process is most intense in the areas of downwelling and intensifies in the autumn period, when thermal stratification is relatively weak. Another important reason is the entrainment of salty Mediterranean waters in the upper part of the Black Sea halocline, which is modulated by the deepening of the seasonal thermocline near the Bosphorus strait and mechanical mixing.</p><p>The increase of salinity is compensated during cold winters, when convective mixing transports fresher water influenced by river discharge into lower density layers of the basin and causes a decrease in pycnocline salinity. This process is most intense in the center of the cyclonic gyres, where pycnocline is located closer to the surface and winter temperature reaches minimal values.</p><p>Due to the long-term warming of the Black Sea, the process of freshening of deep layers now is observed only in rare cold years. At the same time, an intensification of wind speed, vorticity, and geostrophic circulation processes promote the blurring of the halocline and the rise of the salinity of the Black Sea upper layers. Such rise begins after 2007 in the upper part of Black Sea halocline (depth 50–100 m) and is traced down to 250 m by 2020.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104321"},"PeriodicalIF":2.4,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141049567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lophelia reefs (Desmophyllum pertusum (Linnaeus, 1758)) in the oxygen minimum zone of the Mauritania/Senegal region – Distribution and health status","authors":"Sidi M.M. Moctar ,&nbsp;Lene Buhl-Mortensen ,&nbsp;Hammoud El Vadhel ,&nbsp;Saikou O. Kide ,&nbsp;Tina Kutti ,&nbsp;Abdoulaye Sarre ,&nbsp;Mohamed El Khalil Med Mahmoud ,&nbsp;Melissa Chierici ,&nbsp;Magatte Niang ,&nbsp;Yngve Johansen ,&nbsp;David Cervantes ,&nbsp;Cristian Munoz Mas","doi":"10.1016/j.dsr.2024.104322","DOIUrl":"10.1016/j.dsr.2024.104322","url":null,"abstract":"<div><p>The occurrence of cold-water coral (CWC) reefs off Northwest Africa that has a broad oxygen minimum zone (OMZ) is poorly studied. A 400 km long almost continuous coral mound chain off Mauritania that was investigated by earlier expeditions revealed mainly dead corals. In 2021, the EAF-Nansen Programme conducted a survey at the border between Mauritania and Senegal with the main objective to map CWCs. Acoustic mapping with multibeam echosounder was used to target mounds at 450–650 m depth and 14 video lines were conducted using a remotely operated vehicle (ROV). The occurrence and health status of CWC reefs along video transects were annotated using the software “CampodLogger”, oceanographic variables were measured using a CTD sonde, and terrain and backscatter analysis were conducted.</p><p>Here we present the environment and health status of 13 Lophelia reefs established in the study area, six of them were large and healthy reefs with areas having 15–50% cover of live colonies. Oxygen concentrations were measured to be as low as 1 ml L⁻¹ and temperature ranged from 8.8 to 11.6° C. We compare reef health with the environmental variables: temp, salinity, oxygen, and particle load. A GIS based model was developed to predict the occurrence of live reefs in the study area based on the observed average range of a set of terrain descriptors measured where live Lophelia reefs occurred.</p><p>Our findings of healthy Lophelia reefs are unexpected and further north in the OMZ reefs have been described as dormant. There is an urgent need for visual seafloor mapping to aid the development of spatial management plans in these understudied waters.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104322"},"PeriodicalIF":2.4,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S096706372400092X/pdfft?md5=9cdb18884bd370494f3b1f82185ef36e&pid=1-s2.0-S096706372400092X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141035842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Radiocarbon-based ages and growth rates of cold-water bamboo corals in the South China Sea","authors":"Haozhuang Wang ,&nbsp;Xiaoli Zhou ,&nbsp;Haowen Dang ,&nbsp;Les Watling ,&nbsp;Zhimin Jian","doi":"10.1016/j.dsr.2024.104323","DOIUrl":"https://doi.org/10.1016/j.dsr.2024.104323","url":null,"abstract":"<div><p>Growth rates of cold-water bamboo corals are of crucial importance for establishing high-resolution chronology and reconstructing the development of these corals. However, due to the difficulty of sampling, their ages and growth rates as well as ecological indications are still fragmentary. In this study, radiocarbon analysis was performed on live-collected bamboo corals from the South China Sea (SCS) to investigate their growth and the controlling environmental factors. The obtained bomb ¹⁴C curve of organic nodes, which is formed by corals via consuming the surface-sourced sinking particulate organic material suggest that the organic nodes can document the upper ocean environmental conditions. The corals with ages up to 829 years have radial growth rates (RGRs) of 7.4–60.0 μm/year (average: 22.9 μm/year). These RGRs are among the lowest values of all the published RGRs of bamboo corals, representing the slow growth of corals in the SCS, and probably results from the low surface productivity. On the other hand, the relatively high coral RGRs at water depths of ∼1000 m and ∼2000 m probably results from the enhanced food availability caused by the strong bottom current at the water mass boundaries in the intermediate and deep waters. Although no significant correlation between the coral RGRs and the ambient environmental conditions were found, the relatively low RGRs of bamboo corals in the SCS clearly imply rather low ability to recover after damage. Further investigation of the environmental conditions controlling the growth of bamboo corals is needed.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104323"},"PeriodicalIF":2.4,"publicationDate":"2024-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140947426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reproductive traits of the deep-sea shrimp Plesionika williamsi (decapoda: Pandalidae) from the eastern-central atlantic","authors":"A. Bautista ,&nbsp;J.G. Pajuelo ,&nbsp;J.A. González ,&nbsp;J.M. Lorenzo ,&nbsp;R. Triay-Portella","doi":"10.1016/j.dsr.2024.104320","DOIUrl":"https://doi.org/10.1016/j.dsr.2024.104320","url":null,"abstract":"<div><p>The reproductive aspects of all <em>Plesionika</em> species are relatively well known worldwide, except for the deepest species of the genus, <em>Plesionika williamsi</em>, for which little information is available throughout its range. The ovarian maturity, sex ratio, brood size, and size-depth distribution of the deep-sea shrimp <em>Plesionika williamsi</em> (Pandalidae) in the Canary Islands (eastern-central Atlantic) were analysed. Ovigerous females were observed all year round, with the highest number of ovigerous females recorded between July and October. The presence of a greater number of ovigerous females during the summer may reflect a high local availability of food or the optimal abiotic conditions, which are factors with a strong influence on reproduction. The presence of non-ovigerous mature females throughout the year indicates that their resting period in the reproductive cycle occurs asynchronously. The physiological size at first sexual maturity was 19.24 mm in carapace length (CL) and the length at first sexual maturity was estimated at 23.15 mm CL. Estimates of size at first sexual maturity based on ovigerous females describe the result of the reproduction process, whereas size at first sexual maturity based on ovarian maturity deals with physiological preparation for reproduction. The modal size class of egg production was 24–30 mm CL, which yielded 83.22% of the population egg production. <em>Plesionika williamsi</em> is an iteroparous species that can produce small eggs during egg extrusion. The mean number of external embryos carried by females was 3048 and can be considered a true approximation of the number of larvae released in each batch, which depend on the conditions existing in each system. The shallower individuals are associated with a depth stratum that represents the boundary between two water masses present in the Canary Islands. The increase in size with depth is related to the presence of submarine volcanic canyons, which constitutes a flow channel of surface organic matter to depth.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104320"},"PeriodicalIF":2.4,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0967063724000906/pdfft?md5=e05a7d7fd3d002fc7b5e0d7668f4a6c0&pid=1-s2.0-S0967063724000906-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140918940","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Lagrangian characterization of the southwestern Atlantic from a dense surface drifter deployment","authors":"M. Saraceno ,&nbsp;N. Bodnariuk ,&nbsp;L.A. Ruiz-Etcheverry ,&nbsp;M. Berta ,&nbsp;C.G. Simionato ,&nbsp;F.J. Beron-Vera ,&nbsp;M.J. Olascoaga","doi":"10.1016/j.dsr.2024.104319","DOIUrl":"10.1016/j.dsr.2024.104319","url":null,"abstract":"<div><p>The Southwestern Atlantic (SWA) is characterized by its large Eddy Kinetic Energy as the result of the confluence of two major western boundary currents, the northward flowing Malvinas Current (MC) and the southward flowing Brazil Current. The SWA study was addressed in the literature based on altimetry data, in situ measurements, regional models and ocean reanalysis. The present study constitutes the first effort to sample a portion of the SWA, with a dense drifter array (N = 62) deployment. The drifters, drogued at 15 m depths, were deployed across the MC and the Argentine Continental Shelf along two zonal transects located at 47°S and 47.25°S, between the 8th and the September 9, 2021. Drifters were set to deliver their position every 10 and 60 min, providing accurate Lagrangian trajectories that provide information on a large range of space and time scales of the surface currents. Three regions are clearly identified based on the analysis of the speed of the drifters, of their trajectories and of the spectral density of their velocities: the continental shelf, the slope and the open ocean. The comparison of the trajectories of the drifters with satellite altimetry images shows that, in general, drifters follow mesoscale features that are detectable in satellite altimetry maps. The analysis of the drifter trajectories also allowed us the study of submesoscale features of the flow (1–10 km) that are not observable in satellite altimetry data. Comparison with cloud-free, high-resolution color images, shows that drifter trajectories organized by the mesoscale flow might also locally follow sub-mesoscale features. In frontal regions it was found that drifter velocities double satellite altimetry geostrophic velocities, which suggests that the dynamics at those regions is largely dominated by ageostrophic components. The ageostrophic Ekman component might explain the direction of the drifters when strong winds from a given direction prevail for several days and the drifters are not in a region with large sea surface height (SSH) gradients. The joint analysis of drifters’ trajectory and SSH clearly depicts that mesoscale features on the open ocean region control the cross-shelf exchanges between the MC and open ocean regions as well as the strength and width of the MC. Finally, the spatial density distribution of the drifters during the first hours after deployment and within a small eddy also allowed us to characterize the flow in terms of its divergence, vorticity and strain, indicating that the MC is geostrophic and has a jet-like behavior while the eddy is largely ageostrophic and has a dominant vorticity component over strain. We conclude observing that the analysis of a dense array of drifters provides valuable information of the flow that cannot be attained solely based on satellite data.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104319"},"PeriodicalIF":2.4,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141038678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Seasonality and potential generation mechanisms of submesoscale processes in the northern Bay of Bengal","authors":"Yifei Zhou,&nbsp;Wei Duan,&nbsp;Haijin Cao,&nbsp;Guidi Zhou,&nbsp;Rong Cui,&nbsp;Xuhua Cheng","doi":"10.1016/j.dsr.2024.104318","DOIUrl":"https://doi.org/10.1016/j.dsr.2024.104318","url":null,"abstract":"<div><p>The seasonality and generation mechanisms of submesoscale processes (SMPs) in the northern Bay of Bengal (nBoB) are investigated by the outputs of a high-resolution model simulation. The results show that the nBoB has abundant energetic SMPs, with significant seasonal features and geographic variability. The head basin (region A) and central basin (region B) of the nBoB are identified as two typical spots of submesoscale motions. Seasonally, SMPs in region A are strongest in spring and are closely correlated with strong mesoscale strain. By contrast, SMPs in region B are more active in winter and late summer due to the combined effects of deep mixed layer and large mesoscale strain. Energy analysis suggests that baroclinic instability is a dominant generation mechanism for energetic SMPs in region B during winter and summer periods. During spring, the prevalent submesoscale kinetic energy (KE) reservoir in region A is fueled by wind forcing, buoyancy conversion, and the forward KE cascades from mesoscale processes, and mainly balanced by the inverse KE cascades from submesoscale to large-scale processes.</p></div>","PeriodicalId":51009,"journal":{"name":"Deep-Sea Research Part I-Oceanographic Research Papers","volume":"208 ","pages":"Article 104318"},"PeriodicalIF":2.4,"publicationDate":"2024-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140909912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}