Progress in Oceanography最新文献

{"title":"Subsurface evolution of three types of surface marine heatwaves over the East Sea (Japan Sea)","authors":"J.S. Saranya ,&nbsp;SungHyun Nam","doi":"10.1016/j.pocean.2024.103226","DOIUrl":"10.1016/j.pocean.2024.103226","url":null,"abstract":"<div><p>Extremely high seawater temperatures (beyond the 90th percentile threshold) are a key characteristic of marine heatwaves (MHWs), which adversely affect human and marine ecosystems. It is important to characterize the MHWs in the East Sea (Japan Sea), a semi-enclosed deep basin connected to the outside seas/ocean by shallow and narrow straits, where the most rapid upper ocean warming has been reported in recent decades. Despite several reports on their rising frequency and severity, the characteristics, and underlying dynamics of East Sea MHWs (ESMHWs), particularly their subsurface evolution, remain poorly understood. In this study, we aimed to understand the subsurface evolution patterns of ESMHWs and the underlying mechanisms. Here, summer (June, July, and August) ESMHWs from four ocean reanalysis products were characterized after being verified against those from long-term (2000–2015) time-series observations near the east coast of Korea. We found the HYCOM reanalysis products is the best match with the observation, showing consistent evolution patterns with the ESMHWs in the observation, yielding high correlation coefficients (ranging from 0.7 to 0.9 at the surface), and low root-mean-square errors (3°C). Therefore, the HYCOM reanalysis is further used to characterize the subsurface evolution of surface ESMHWs. A rising frequency of annual mean and summer ESMHWs across the whole East Sea, with a maximum increasing rate of 1–2 events in 40 years and mean cumulative intensity of 5–9°C days decade^-1. Three types (Types-A, -B, and -C) of subsurface evolution of ESMHW were commonly found in six sub-regions (where the increasing ESMHWs trends are maximum)—three in the western and three in the eastern parts. The three types are Type-A, which is surface-confined and short-lived with anomalous warm surface temperatures and cold subsurface temperatures; Type-B, characterized by warm anomalies propagating from the surface to the upper several meters with no subsurface cold anomalies; and Type-C, exhibiting anomalous warm temperatures at the upper 200 m. Although increased shortwave radiation, decreased wind speed, and thinned mixed layer commonly contribute to the formation of all three types, the relative role of the heat penetration into the layer below the mixed layer and dissipation mechanisms significantly differ among the types. Common ESMHW evolution features include mixed layer deepening, heat release to the atmosphere, and interactions between the surface mixed layer and deeper layers, while horizontal advection played a significant role only during the Type-C ESMHW events. The long-term trends in frequency, cumulative intensity, and duration of ESMHWs were discussed in terms of those in each type ESMHWs metrics along with long-term surface warming, subsurface cooling, and weakening currents in the six sub-regions. This study provides significant insights into surface and subsurface evolution of MHWs in this and other margina","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139917050","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":"Biotic transformation of methylmercury at the onset of the Arctic spring bloom","authors":"Stephen G. Kohler ,&nbsp;Lars-Eric Heimbürger-Boavida ,&nbsp;Philipp Assmy ,&nbsp;Oliver Müller ,&nbsp;Stefan Thiele ,&nbsp;Maria G. Digernes ,&nbsp;Kuria Ndungu ,&nbsp;Murat V. Ardelan","doi":"10.1016/j.pocean.2024.103224","DOIUrl":"10.1016/j.pocean.2024.103224","url":null,"abstract":"<div><p>Despite the lack of local anthropogenic mercury sources, methylated mercury (MeHg) concentrations in Arctic biota are higher than in biota from lower latitudes. The main entry route occurs during the bioconcentration of seawater monomethylmercury (MMHg) into phytoplankton. Despite the known seasonal changes in biological activity in the region, little is known about the seasonal cycling of total mercury (THg) and MeHg in the Arctic Ocean. Here, we report the concentrations of THg and MeHg in seawater sampled from the northwestern Barents Sea water column during late winter and spring. In the upper 500 m, the THg concentrations are significantly higher in spring (0.64 ± 0.09 pmol L^-1) compared to late winter (0.53 ± 0.07 pmol L^-1), driven by seasonal inputs to surface waters from atmospheric deposition and the dynamics of changing sea ice conditions. Contrastingly, the MeHg concentrations in spring were significantly lower (41 ± 39 fmol L^-1) compared to late winter (85 ± 42 fmol L^-1). We suggest that most MeHg is biotically demethylated by both phytoplankton and bacteria, with additional losses from photodemethylation and evasion. Our observations highlight the importance of demethylation during potential uptake of methylmercury coinciding with the Arctic spring bloom. Lastly, we use our new data together with previously published seasonal data in the region to construct a simplified seasonal mercury cycle in an Arctic marginal ice zone.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0079661124000302/pdfft?md5=0fbbf50c39aaaee0b0bf2733e380a0cc&pid=1-s2.0-S0079661124000302-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139916904","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":"Semidiurnal Internal Tides in a Shelf Sea South of Japan: Characteristics, Energetics, and Temporal variations","authors":"Shuya Wang ,&nbsp;Xinyu Guo ,&nbsp;Akihiko Morimoto ,&nbsp;Anzhou Cao ,&nbsp;Eisuke Tsutsumi ,&nbsp;Yasumasa Miyazawa ,&nbsp;Sergey M. Varlamov","doi":"10.1016/j.pocean.2024.103229","DOIUrl":"10.1016/j.pocean.2024.103229","url":null,"abstract":"<div><p>Tidal mixing in a shelf sea south of Japan (Bungo Channel) plays an important role in modulating the water exchange between the Seto Inland Sea and Pacific Ocean. In this study, based on moored observations and model results from the Japan Coastal Ocean Predictability Experiment—Tides (JCOPE-T), the generation, propagation, and dissipation of semidiurnal internal tides in the Bungo Channel are investigated. Observational results indicate that semidiurnal internal tides induce strong baroclinic currents reaching 0.3 m/s. Their energy shows obvious spring-neap tidal cycles, generally coinciding with the local barotropic tidal forcing. By conducting the empirical orthogonal function analysis, we find that the observed semidiurnal internal tides are mainly dominated by the first two baroclinic modes. The JCOPE-T results suggest two main generation sites for semidiurnal internal tides in the region: one is located at a narrow strait north of the Bungo Channel, while the other is at the shelf break south of the Bungo Channel. The latter makes a major contribution to the observed semidiurnal internal tides. Northward internal tides generated at the shelf break are superposed with those generated at the narrow strait, causing a complex interference pattern in the channel. The temporal variation of semidiurnal internal tides in the Bungo Channel is affected by several factors. The intraseasonal variation of semidiurnal internal tides can be modulated by the Kuroshio warm water intrusion (<em>Kyucho</em>) because the occurrence of <em>Kyucho</em> changes the stratification in the channel and hence affects the energy conversion. The seasonal variation of semidiurnal internal tides in the Bungo Channel is determined mainly by the seasonally varying stratification; while those generated at the shelf break are under the combined influence of seasonal stratification and background currents. Southward internal tides from the shelf break are refracted due to the spatially varying stratification and background currents. The varying Kuroshio path and strength modulate the refraction of internal tides.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139916857","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":"Analysis of vortex merging from a rotating tank laboratory experiment","authors":"Minghan Fu ,&nbsp;Guoqing Han ,&nbsp;Xiaojie Lu ,&nbsp;Wenjin Sun ,&nbsp;Joel Sommeria ,&nbsp;Alexandre Stegner ,&nbsp;Rui M.A. Caldeira ,&nbsp;Changming Dong","doi":"10.1016/j.pocean.2024.103227","DOIUrl":"https://doi.org/10.1016/j.pocean.2024.103227","url":null,"abstract":"<div><p>Oceanic vortex merging is an important physical process for the vortex evolution and its impact on marine environment. However, limitation of the in-situ oceanic observational data of vortex merging inhabits its better understanding. This study investigates the interactions between non-ideal vortices in a four-vortex flow field in a rotating tank. We examine the merging stages of anticyclonic vortices, influenced by two other cyclonic vortices and their respective dynamical behaviors and quantify the effects of merging on vortex characteristics. The results indicate a strong shear flow between two counter-rotating vortices, which accelerates the motion of the anticyclonic vortex, while cyclonic ones exhibit greater stability. Subsequently, different stages of non-ideal vortex merging in a co-rotating framework are defined, primarily the encircling stage, rapid approaching stage, and merging vortex stage. In addition, we quantify and compare variations in morphological parameters and anti-symmetric vorticity distribution of non-ideal vortices across these stages. The stretching of vortices primarily occurs along the line connecting their centers due to the strain field exerted by neighboring vortices, resulting in an asymmetric stretching pattern in the interactions among non-ideal vortices. Furthermore, during the merging process, non-ideal vortices disperse vorticity outward and accumulate vortex filaments in the surrounding environment, leading to distinctive variations in anti-symmetric vorticity distribution, affecting their respective merging efficiency.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139748762","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":"Microeukaryotes have unexpected importance in cold seep food webs through predation and parasitism","authors":"Longzhao Li ,&nbsp;Feng Zhao ,&nbsp;Sabine Filker ,&nbsp;Weiyue Liu ,&nbsp;Rongjie Zhao ,&nbsp;Yuanyuan Wan ,&nbsp;Kuidong Xu","doi":"10.1016/j.pocean.2024.103216","DOIUrl":"https://doi.org/10.1016/j.pocean.2024.103216","url":null,"abstract":"<div><p>Cold seeps are inhabited by a high abundance of chemosynthetic prokaryotes and invertebrates. However, a complete food web between invertebrates and prokaryotes cannot be established without the important link of microeukaryotes. Yet, question such as which microeukaryotes are at work in cold seeps is still mostly open. We, therefore, compared the biological communities in cold seeps and adjacent areas of the South China Sea by the metabarcoding and quantitative PCR (qPCR) of nuclear 18S and 16S rRNA genes, and estimated the potentially ecological roles of microeukaryotes by cross-domain microbial network analysis. The anaerobic methane oxidizing archaea (ANME), sulfate-reducing bacteria (SRB) and Radiolaria accounted for most variations between microbial communities from the cold seeps and adjacent areas. A significant correlation was detected between the copy numbers of 18S rRNA gene and communities of the ANME and SRB in cold seeps, indicating close links between microeukaryotes and chemosynthetic prokaryotes. After adding microeukaryotic nodes microbial network became more complex, and the negative correlation proportion and average path length increased, suggesting increased predation and parasitism. The ANME and SRB groups were mainly negatively correlated with and potentially preyed by Acantharea and Cercozoa, which were then negatively correlated with annelids and mollusks. Parasitic microeukaryotes of Syndiniales widely existed in cold seeps and had close relationships with Polycystinea. Parasitism might cause the death of Polycystinea and the release of Syndiniales spores, which may be an important carbon source for the cold seep biota. Using Mantel analyses, we also demonstrated that trophic relationships are closer in cold seeps than in the adjacently deep-sea sediments, and that microeukaryote-metazoans linkages in cold seeps are closer than those between prokaryotes and metazoans. Overall, our study outlines the main components of food webs in cold seeps and highlights that microeukaryotes have an unexpected importance in the carbon cycle.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139748761","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":"Improving coral monitoring by reducing variability and bias in cover estimates from seabed images","authors":"Emma J. Curtis ,&nbsp;Jennifer M. Durden ,&nbsp;Brian J. Bett ,&nbsp;Veerle A.I. Huvenne ,&nbsp;Nils Piechaud ,&nbsp;Jenny Walker ,&nbsp;James Albrecht ,&nbsp;Miquel Massot-Campos ,&nbsp;Takaki Yamada ,&nbsp;Adrian Bodenmann ,&nbsp;Jose Cappelletto ,&nbsp;James A. Strong ,&nbsp;Blair Thornton","doi":"10.1016/j.pocean.2024.103214","DOIUrl":"https://doi.org/10.1016/j.pocean.2024.103214","url":null,"abstract":"<div><p>Seabed cover of organisms is an established metric for assessing the status of many vulnerable marine ecosystems. When deriving cover estimates from seafloor imagery, a source of uncertainty in capturing the true distribution of organisms is introduced by the inherent variability and bias of the annotation method used to extract ecological data. We investigated variability and bias in two common annotation methods for estimating organism cover, and the role of size selectivity in this variability. Eleven annotators estimated sparse cold-water coral cover in the same 96 images with both grid-based and manual segmentation annotation methods. The standard deviation between annotators was three times greater in the grid-based method compared to segmentation, and grid-based estimates from annotators tended to overestimate coral cover. Size selectivity biased the manual segmentation; the minimum size of colonies segmented varied between annotators fivefold. Two modelling techniques (based on Richard’s selection curves and Gaussian processes) were used to impute areas where annotators identified colonies too small for segmentation. By imputing small coral sizes in segmentation estimates, the coefficient of variation between annotators was reduced by approximately 10%, and method bias (compared to a reference dataset) was reduced by up to 23%. Therefore, for sparse, low cover organisms, manual segmentation of images is recommended to minimise annotator variability and bias. Uncertainty in cover estimates may be further reduced by addressing size selectivity bias when annotating small organisms in images using a data-driven modelling technique.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139714245","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":"Spatial and temporal variations in the micronutrient Fe across the Peruvian shelf from 1984 to 2017","authors":"Yuanyuan Gu ,&nbsp;Mark James Hopwood ,&nbsp;Martha Gledhill ,&nbsp;Insa Rapp ,&nbsp;Kathrin Wuttig ,&nbsp;Eric Pieter Achterberg","doi":"10.1016/j.pocean.2024.103208","DOIUrl":"10.1016/j.pocean.2024.103208","url":null,"abstract":"<div><p>High dissolved iron (dFe) concentrations of the order of 10–100 nmol L⁻¹ are a feature of waters influenced by sedimentary inputs in oxygen minimum zones (OMZ). However, the temporal development of dFe concentrations is poorly defined due to a general reliance on snapshot cross-shelf sections to study marine trace metal dynamics. Multiple cruise campaigns since the 1980s have investigated Fe dynamics over the Peruvian shelf, particularly between 9° S and 17°S where the shelf is broad, extremely productive and known to feature benthic dFe effluxes which are amongst the highest measured globally. This extensive long-term dataset uniquely allows us to study the interannual variability in dFe concentrations and their response to El Niño–Southern Oscillation (ENSO) events. By combining data from 11 cruises during the period 1984–2017 we are able to evaluate dFe dynamics on interannual timescales in a major OMZ. The region where average dFe concentrations are sensitive to variations in ENSO is confined to a subsurface layer at depths between 50 and 150 m, particularly in the narrow coastal region within 50 km of the coastline. Subsurface dFe concentrations were generally low during El Niño events (0.7–15.4 nmol L⁻¹) and relatively high with a wider range of variability during the cold ENSO phase (1.1–52.1 nmol L⁻¹). Inverse relationships between wind speed and surface/subsurface dFe were evident. In the subsurface layer, this may be attributable to enhanced dFe offshore transport along isopycnals when upwelling-favorable winds relax in accordance with previously outlined theories. Surface layer (&lt;40 m) dFe variability was likely associated with a dilution and/or oxidation effect depending on the strength of wind driven water column mixing. Upwelling brings macronutrient-rich water into the euphotic zone, but its intensity had a limited impact on upper layer dFe concentrations possibly due to the influence of an onshore geostrophic flow. Interannual variability in surface chlorophyll-a (Chl-a) was found to correlate with dFe concentration in the offshore zone of northern Peru. This is consistent with bioassay experiments and climatological residual nitrate concentrations which both indicate proximal Fe limitation of phytoplankton growth over and beyond the northern Peruvian shelf. Overall, our work highlights the importance of physical factors driving short-term variations in Fe availability in one of the world’s most economically important fishery regions and suggests that, despite pronounced spatial and temporal variability in dFe concentrations, the ENSO phase has an impact on dFe availability.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139489946","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":"How membrane fatty acids influence sardine size across diverse marine environments","authors":"Margaux Mathieu-Resuge ,&nbsp;Pablo Brosset ,&nbsp;Fany Sardenne ,&nbsp;Philippe Soudant ,&nbsp;Fabienne Le Grand ,&nbsp;Quentin Schull ,&nbsp;Christophe Lebigre","doi":"10.1016/j.pocean.2024.103209","DOIUrl":"10.1016/j.pocean.2024.103209","url":null,"abstract":"<div><p>Differences in diet quality and quantity may influence trophodynamic processes in small pelagic fish. Yet, we currently lack direct and comprehensive information on how large-scale areas differ in dietary resources and the degree to which these differences influence fish physiological performances (i.e., growth), ultimately influencing entire fish stocks. Fatty acid composition is one of the bioindicator that can provide insights on how dietary provisions of essential lipids influence the structure of the membrane fatty acids and subsequently fish growth among contrasted habitats. To address this issue, we conducted a large-scale sampling of European sardine (<em>Sardina pilchardus</em>) a species with major socio-economic importance that plays a key role as an energy pathway linking lower and upper trophic levels in pelagic ecosystems. We sampled individuals from the Gulf of Lions (Mediterranean Sea), the Bay of Biscay, and the English Channel (Atlantic Ocean) of age-0 to −3 + and found clear spatial differences in the quantity and quality of dietary lipids. Sardines from the Gulf of Lions fed on trophic food web based on dinoflagellates, with greater proportions of DHA (22:6n-3; docosahexaenoic acid) in reserve lipids. Sardines’ reserve lipids had important proportions of zooplankton biomarkers in the English Channel (e.g., 20:1n-9 and 20:1n-11), and diatoms biomarkers such as 16C fatty acids and EPA (20:5n-3; eicosapentaenoic acid) in the Bay of Biscay. The relationship between sardines’ membrane fatty acid composition and individuals’ length changed progressively with individuals’ age, a result consistent across areas, indicating ontogenetic abilities between largest and smallest individuals. Before maturity, largest sardines had higher DHA proportions, followed after maturity by higher proportions of ARA (20:4n-6; arachidonic acid), EPA and DPA (22:5n-3; docosapentaenoic acid). Finally, the study highlights the importance of considering the quality and diversity of dietary resources to better understand how individuals cope with their physiological needs. It is thus important to consider combined aspects (e.g., diet quality and diversity, influence of particular nutrients on length) to better understand the underlying mechanistic processes influencing fish physiology, likely cascading to different expression of their life history traits and affecting fisheries stocks.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0079661124000156/pdfft?md5=0786b7c316cc2352126bef53f69df449&pid=1-s2.0-S0079661124000156-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139670623","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":"Characteristics of mesoscale eddies and their evolution in the north Indian ocean","authors":"Shiva Shankar Manche,&nbsp;Rabindra K. Nayak,&nbsp;Rajesh Sikhakolli,&nbsp;Rajashree V. Bothale,&nbsp;Prakash Chauhan","doi":"10.1016/j.pocean.2024.103213","DOIUrl":"10.1016/j.pocean.2024.103213","url":null,"abstract":"<div><p>Mesoscale eddies are ubiquitous in the oceans and play a significant role in setting the turbulence, transporting momentum, heat, salinity, and nutrients from their formation site to the place of dissipation, and controlling biogeochemical processes and air-sea exchanges. Using satellite-measured daily sea level anomaly from 1993 to 2021, we studied statistical characteristics of mesoscale eddies in the north Indian Ocean. The procedure uses information on the vorticity vector, Okubo-Weiss velocity gradient tensor and its threshold, and Lagrange transport. The continental margin of the Arabian Sea (AS) with its western and northeastern flanks, the mouth of the Gulf of Aden, the Lakshadweep Sea, the western margin of the Bay of Bengal (BOB), and the Andaman Sea have been depicted as the hotspot regions. The occurrence of cyclonic eddies (CEs) and anticyclonic eddies (AEs) are comparable in numbers with similar probability distribution as a function of their lifetime in AS and BOB at the basin scale and differ significantly in the regional domains. CEs dominate over AEs during monsoon and post-monsoon periods in the AS and during January-August in the BOB. In contrast, AEs are prominent in the great whirl (GW) during the monsoon period, and the EICC exhibits their peaks in March, July and November. Among the total observed eddies during the study period, 87 % of which are short-lived (&lt;30 days), 10 % are moderately lived (30–60 days), and 3 % are long-lived (&gt;60 days). Eddies are smaller and less energetic, with longer life in the higher latitudes than the lower latitudes. The frequency of eddies exhibits distinct seasonal variability with preferred periods during May-August and November-March, respectively, for their occurrence in AS and BOB. They also show significant inter-annual oscillations and decreasing trends on the background of the weak boundary currents.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139660850","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":"Modular ocean trace elements sampling for the international GEOTRACES studies – Evidence from analysis of dissolved Fe and Pb","authors":"J. Zhang ,&nbsp;Z.T. Ni ,&nbsp;J.L. Ren ,&nbsp;F. Yu ,&nbsp;X.Y. Diao ,&nbsp;Y. Wang ,&nbsp;S.J. Zhang ,&nbsp;H. Su ,&nbsp;S.L. Cong ,&nbsp;Z.J. Lu ,&nbsp;S. Jiang ,&nbsp;J. Ou ,&nbsp;Y. Chen ,&nbsp;Q. Wang ,&nbsp;Z.B. Zhang ,&nbsp;J.T. Ai ,&nbsp;C.B. Wang ,&nbsp;Z.D. Tao","doi":"10.1016/j.pocean.2024.103212","DOIUrl":"10.1016/j.pocean.2024.103212","url":null,"abstract":"<div><p>A new modular system was reported in this paper for the purpose of sampling and processing of trace elements in the open ocean. The idea of designing is based on the concept of assembly and combination, which is so called “Modular Ocean Trace Elements Sampling” (MOTES). In application, the system is tested during a cruise in the Subtropical Pacific Ocean between 140° E to 142° E, and between 6° N and 20° N, with sampling water depth down to 7000 m. The results provide evidences for low procedural blanks and good reproducibility in repeated samplings through the entire water column for trace elements work. Data illustrate low, reproducible and representative concentrations of dissolved Fe (dFe) and Pb (dPb) compared to the results reported in the literature and show the consistency of oceanographic profiles in sub-basin-wide spatial dimensions.</p></div>","PeriodicalId":20620,"journal":{"name":"Progress in Oceanography","volume":null,"pages":null},"PeriodicalIF":4.1,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139670528","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}