Compared with the laboratory acoustic measurement of sediment samples, the in-situ acoustic measurement in marine sediment is considered more accurate and rehable, because it covers all of the surrounding environment ...Compared with the laboratory acoustic measurement of sediment samples, the in-situ acoustic measurement in marine sediment is considered more accurate and rehable, because it covers all of the surrounding environment factors and avoids the disturbance during the course of sampling and transporting of sediment samples. A new multi-frequency in-situ geoacoustic measurement system （MFIS^AMS） has been developed. The system can provide acoustic vdocity （compressional wave） and attenuation profiles of the uppermost 4 - 8 m sediment in the seafloor. It consists of 8 channels with 12 frequencies （multi-frequencies） and 0.5 - 2 MHz sampling rates. The data collected can be transmiuted in real-time. Associated with inclinometer and altimeter, it can provide the data for depth emendation. Acoustic velocity and attenuation data have been obtained from two in-situ experiments conducted in the Hangzhou Bay.展开更多
Internal solitary waves(ISWs) contain great energy and have the characteristics of emergency and concealment. To avoid their damage to offshore engineering, a new generation of monitoring and early warning system for ...Internal solitary waves(ISWs) contain great energy and have the characteristics of emergency and concealment. To avoid their damage to offshore engineering, a new generation of monitoring and early warning system for ISWs was developed using technologies of double buoys monitoring, intelligent realtime data transmission, and automatic software identification. The system was applied to the second natural gas hydrates(NGHs) production test in the Shenhu Area, South China Sea(SCS) and successfully provided the early warning of ISWs for 173 days(from October 2019 to April 2020). The abrupt changes in the thrust force of the drilling platform under the attack of ISWs were consistent with the early warning information, proving the reliability of this system. A total of 93 ISWs were detected around the drilling platform. Most of them occurred during the spring tides in October–December 2019 and April 2020, while few of them occurred in winter. As suggested by the theoretical model, the full-depth structure of ISWs was a typical current profile of mode-1, and the velocities of wave-induced currents can reach 80 cm/s and30 cm/s, respectively, in the upper ocean and near the seabed. The ISWs may be primarily generated from the interactions between the topography and semidiurnal tides in the Luzon Strait, and then propagate westward to the drilling platform. This study could serve as an important reference for the early warning of ISWs for offshore engineering construction in the future.展开更多
In the numerical studies of a real tide M4 resonance system, the Xiangshan Port which is a partially-closed bay, Dong et al. [1999. Acta Oceanologica Sinica, 21 （3）： 1-6] found the interesting phenomenon that the a...In the numerical studies of a real tide M4 resonance system, the Xiangshan Port which is a partially-closed bay, Dong et al. [1999. Acta Oceanologica Sinica, 21 （3）： 1-6] found the interesting phenomenon that the advection plays an important role in inhibiting the growth of the amplitude of the tidal second-order resonance response （M4）. This result is contrary to the general traditional ideas for a non-resonance system. How this phenomenon is interpreted and what internal mechanism is behind the phenomenon are the main focuses of this study. The followings are examined： （1） the dynamic features of a second-order resonance system of tide; （2） the dominating factors on the second-order resonance responses; （3） the effects of both the friction and the advection on the second-order resonance responses; and （4） their roles in dominating the second-order resonance response and internal mechanisms by using the analytical methods. The respective results show that： （1） Both the bottom friction and the advection play significant roles in dominating the magnitude of the amplitude of the second-order resonance responses; （2） the effect of the friction on the second-order resonance response depends on the distribution ratio of the work-done of the system to friction force exhausted into between the damping of the first-order system and the inner excitation of the second-order system; （3） the advection plays a positive role in increasing the amplitude of the second-order non-resonance response in the second order non-resonance of tide; （4） in a second-order resonance system of tide, the effect of the advection may be either to increase or to decrease the amplitudes of the second-order resonance responses of tide, which depends on the distribution ratio mentioned above.展开更多
Polynyas and their adjacent seasonal ice zones(SIZs)represent the most productive regions in the Southern Ocean,supporting unique food webs that are highly sensitive to climate change.Understanding the dynamics of phy...Polynyas and their adjacent seasonal ice zones(SIZs)represent the most productive regions in the Southern Ocean,supporting unique food webs that are highly sensitive to climate change.Understanding the dynamics of phytoplankton and the carbon pool in these areas is crucial for assessing the role of the Southern Ocean in global carbon cycling.During the late stage of an algal bloom,seawater samples at 14 stations were collected in the Amundsen Sea Polynya(ASP)and adjacent SIZ.Using nutrients,phytoplankton pigments,organic carbon(OC),remote sensing data,and physicochemical measurements,as well as CHEMTAX model simulations,we investigated the response of the phytoplankton crops,taxonomic composition,and OC pool to environmental factors.Our analyses revealed that hydrodynamic regimes of the polynya,adjacent SIZs and open sea were regulated by the regionally varying intrusion of Circumpolar Deep Water,photosynthetically active radiation and sea ice melt water.The ASP exhibited the highest seasonal nutrient utilization rates[ΔN=(1059±386)mmol/m^(2),ΔP=(50±17)mmol/m^(2) andΔSi=(956±904)mmol/m^(2)],while the open sea had lower rates.The integrated chlorophyll a(Chl a)concentration at depths of 0–200 m ranged from 20.4 mg/m^(2) to 1420.0 mg/m^(2) and peaked in the polynya.In the study area,Haptophytes Phaeocystis antarctica was the dominant functional group(34%±27%),and diatoms acted as a secondary contributor(23%±14%).The major functional group and particulate OC(POC)contributor varied from diatoms(36%±12%)in the open sea to haptophytes(48%±31%)in the polynya waters.Strong light conditions and microelement limitations promoted the dominance of P.antarctica(low Fe forms)dominance in the ASP.The strong correlations between the POC and Chl a depth-integrated concentration suggest that the POC was primarily derived from phytoplankton,while dissolved OC(DOC)was influenced by consumer activity and water mass transport.In addition,the transport of OC in the upper 200 m of the water column within the ASP was quantified,revealing the predominantly westward fluxes for both DOC[9.0 mg/(m^(2)·s)]and POC[7.2 mg/(m^(2)·s)].The latitudinal transport exhibited the northward transport of DOC[8.1 mg/(m^(2)·s)]and southward transport of POC[4.3 mg/(m^(2)·s)]movement.These findings have significant implications for enhancing our understanding of how hydrodynamics influence OC cycling in polynya regions.展开更多
The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of ...The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated.In this study,we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021,noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter.We analyzed sediment trap data,which included total mass flux(TMF),particulate organic carbon(POC),biogenic silica(BSi),particulate inorganic carbon,and lithogenic particle(Litho)fluxes,as well as the stable isotopesδ^(13)C andδ^(15)N of particulate organic matter(POM).Additionally,we incorporated remote sensing data on sea ice concentration and chlorophyll a.This dramatic delay in sea ice melting timing could result in a significant increase in TMF,BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020.Elevated BSi fluxes and more ^(13)C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms.Furthermore,the higher BSi/POC ratio and more negativeδ^(15)N values of POM,along with a reduced presence of krill in the traps,indicate a diminished grazing pressure from zooplankton,which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021.These findings highlight the critical role of sea ice melting timing in regulating productivity,flux and composition of sinking particulate matter in the Prydz Bay ecosystem,with significant implications for carbon cycling in polar oceans.展开更多
The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved ...The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.展开更多
Dissolved organic carbon(DOC)constitutes the largest organic carbon reservoir in the ocean and plays a vital role in the oceanic carbon cycle.However,research on DOC in Antarctica has been limited,largely due to diffi...Dissolved organic carbon(DOC)constitutes the largest organic carbon reservoir in the ocean and plays a vital role in the oceanic carbon cycle.However,research on DOC in Antarctica has been limited,largely due to difficulties in sample collection.In this study,we investigate chromophoric dissolved organic matter(CDOM)in the Cosmonaut Sea and Cooperation Sea,Antarctica.The relative abundances of CDOM,as indicated by the absorption coefficient at 254 nm(a_(254)),exhibit significant variability,ranging from 1.29 m^(-1) to 8.37 m^(-1).The diatom species B is the primary contributor to CDOM in the region influenced by the Antarctic slope current.Using excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis(EEM-PARAFAC),we identify three fluorescent components:one protein-like component(C1)and two humic-like components(C2 and C3).Our findings indicate that strong microbial activity in the euphotic zones of the Cosmonaut Sea and Cooperation Sea serves as a primary pathway for the removal of protein-like substances while also acting as a significant source of humic-like substances.Microbial degradation likely accounts for the decoupling of the vertical distribution of DOC and phytoplankton.Furthermore,the intrusion of modified circumpolar deep water(mCDW)into the euphotic zones of open ocean areas influences the distribution of CDOM at depths shallower than 200 m.These results have important implications for enhancing our understanding of the dynamics of CDOM and DOC in east Antarctica,as well as for improving assessments of the carbon cycle.展开更多
This study examines the multi-scale spatio-temporal evolution of drought characteristics in Zhejiang Province.We propose a comprehensive index to identify drought days and events by incorporating three widely used mon...This study examines the multi-scale spatio-temporal evolution of drought characteristics in Zhejiang Province.We propose a comprehensive index to identify drought days and events by incorporating three widely used monitoring indices:the precipitation anomaly percentage,relative humidity index,and standardized precipitation index.The analysis reveals a significant long-term decreasing trend in the frequency of drought days across Zhejiang Province from 1971 to 2020,with a total of 170 drought events being identified.An Empirical Orthogonal Function(EOF)analysis of precipitation anomalies during these events reveals a dominant province-wide monopole mode,alongside a secondary northsouth inverse dipole,a third tripole,and a fourth southwest-northeast inverse dipole.Furthermore,a composite analysis of the drought events demonstrates a widespread increase in temperature across all stations,with a strong spatial correspondence between the temperature anomalies and their associated frequency.The study identifies 21 extreme drought events,characterized by spatially inconsistent precipitation patterns across the entire province.展开更多
Microplastics(MPs)have garnered significant international scrutiny as an emerging environmental pollutant,constituting one of the four principal global environmental threats and posing potential health hazards to huma...Microplastics(MPs)have garnered significant international scrutiny as an emerging environmental pollutant,constituting one of the four principal global environmental threats and posing potential health hazards to humans.However,data on the impact of MPs on the early life of the commercially important fish remain limited.In this study,polystyrene microspheres(PS-MPs)(1 and 5μm)were used to investigate the effects of MPs on the growth,development,and metabolism in early life stages of large yellow croaker Pseudosciaena crocea.Results indicate that MPs were enriched in the gastrointestinal tract and gills of the fish.In addition,PS-MPs(1μm)exhibited no obvious effects on embryo hatching and heart rates,while increased the mortality rate(23.00%vs.control 14.99%)and decreased the body length(4098.61±447.03μm vs.control with 2827.04±254.75μm)of the larvae at the highest exposure concentration(5×10^(4)items/L).Metabolomics analysis revealed that PS-MPs(5μm)induced mild perturbations in phospholipid metabolism,specifically alterations in phosphatidylethanolamine(PE)levels.These changes influenced the cell membranes of juvenile fish,and consequently elicited inflammatory responses,disrupted lipid homeostasis,and affected other critical physiological processes.Ultimately,these effects may avoid the growth retardation and potential mortality.Therefore,PS-MPs could affect negatively the fish health in the early life stage,which has implications for aquatic ecosystems.展开更多
Understanding the sediment record during the Little Ice Age(LIA)can help elucidate natural sea ice fluctuation and carbon cycle variability.This study analyzed the grain size composition(including ice-rafted debris),t...Understanding the sediment record during the Little Ice Age(LIA)can help elucidate natural sea ice fluctuation and carbon cycle variability.This study analyzed the grain size composition(including ice-rafted debris),total organic carbon(TOC),total nitrogen(TN)content,and stable isotopic composition(δ13C andδ15N)of the sediment record(approximately 490 a)of core ARC7-R11 in the northern part of the Chukchi Shelf.The sediment grains comprise mostly(>90%)silt and clay components.The grain size composition suggests generally low-energy hydrodynamic conditions across the region,yet reveals a trend of enhancement in hydrodynamics from the bottom to top layers of the sediment core,particularly after the 1940s.It also shows occurrences of seasonal sea ice and retreat of the perennial sea ice margin during warmer periods of the LIA and the post-LIA period.The organic matter content is high throughout the core,with heavierδ13C values and moderate TOC/TN ratios indicating primarily marine origin;the terrestrial input is<37.5%according to the endmember model.The variation trend of marine-derived organic carbon(OC)content is similar to that of summer temperature anomalies;while variation trend of terrestrially derived OC shows significant correlation with that of the number of ice-free days in the southern shelf region,except for the period from approximately 1700s to the 1870s.During the LIA,the TOC content fluctuated and decreased,and the relative contribution of terrestrial OC was higher than during the modern warm period.The amount of OC buried in the sediment has increased with climate warming,especially after the 1940s,reflecting the enhanced ability of sediment to sequester carbon during warmer periods.展开更多
Understanding the seasonal variations of the zooplankton community’s structure in the Western Pacific Warm Pool(WPWP)-the most stable open marine environment in the Pacific Ocean-is crucial to predict the impacts of ...Understanding the seasonal variations of the zooplankton community’s structure in the Western Pacific Warm Pool(WPWP)-the most stable open marine environment in the Pacific Ocean-is crucial to predict the impacts of climate change on the ecosystem.However,knowledge on these variations in this region down to the mesopelagic zone is insufficient.In this study,the environmental DNA(eDNA)metabarcoding method was used to investigate the zooplankton community during summer,autumn,and winter,from the surface to a depth of 1000 m spanning the epipelagic to mesopelagic zones.The zooplankton community structure exhibited seasonal fluctuations at multiple depths except for 200 and 1000 m.In addition,a stronger zooplankton seasonality was particularly recorded in the epipelagic zone than in the mesopelagic zone,which is consistent with the environmental changes.The studied zooplanktons are dominated by medusae and copepods that showed distinct seasonality.At all depths,medusae exhibited greater seasonal variations than the overall zooplankton community,whereas the copepods did not exhibit significant seasonality.The environmental features and the seasons exerted greater influences on the structure of the zooplankton communities than did the spatial factors.The results of this study indicate that eDNA metabarcoding can provide novel insights into zooplankton assemblages due to its ability to capture a rich variety of medusae,which are often underestimated by net collection.展开更多
The inherent asymmetry and diversity of the El Niño-Southern Oscillation(ENSO)pose substantial challenges to its prediction.Potential predictability measures the upper limit of predictability for a certain event....The inherent asymmetry and diversity of the El Niño-Southern Oscillation(ENSO)pose substantial challenges to its prediction.Potential predictability measures the upper limit of predictability for a certain event.Assessing the potential predictability of ENSO across varying phases and intensities with sophisticated climate models is crucial for understanding the upper limits of forecasting capabilities and identifying room for future enhancement.Based on the hindcast dataset with a recently developed ensemble forecasting system(the community earth system model,CESM),this study comprehensively investigates potential predictability for ENSO across different phases and intensities.The findings reveal that La Niña events possess higher potential predictability relative to their El Niño counterparts.Strong events exhibit significantly higher potential predictability than weak events within the same phase.The potential predictability of distinct ENSO types is primarily influenced by the seasonal variation inherent to their predictability.Regardless of the event classification,the potential predictability is characterized by a rapid decline from spring onwards,with the apex of this decline occurring in summer.The intensity of the seasonal predictability barrier inversely correlates with the upper limit of potential predictability.Specifically,a weaker(stronger)seasonal barrier is associated with a higher(lower)potential predictability.In addition,there is significant interdecadal variability both in the predictability of warm and cold ENSO events.The potential predictability for La Niña events decreases more slowly with increasing lead months,particularly in recent decades,resulting in an overall higher upper limit of potential predictability for La Niña events than for El Niño events over the past century.Nevertheless,El Niño events have also maintained a high potential predictability.This suggests substantial potential for improvement in future prediction for both.展开更多
Macrobenthic organisms are commonly employed as biomonitors for environmental risk assessment.In this study,we aimed to investigate the spatial and temporal patterns of the macrobenthic community,which is influenced b...Macrobenthic organisms are commonly employed as biomonitors for environmental risk assessment.In this study,we aimed to investigate the spatial and temporal patterns of the macrobenthic community,which is influenced by environmental factors of sediments and bottom water layer.We sampled a total of 12,11,10,and 11 stations in the Shengsi Archipelago during June 2010,August 2010,November 2020,and April 2021 respectively.A total of 124 species of macrobenthos were identified,with polychaetes being the dominant group.The abundance,biomass,and diversity indices exhibited no significant temporal differences.Similarly,biodiversity did not exhibit a clear spatial gradient,likely due to the small study area and the absence of significant differences in key factors such as depth.However,the stations with the lowest biodiversity values consistently appeared in the southwest region,possibly due to the impact of human activities.Significant differences in the macrobenthic community were observed between all months except between June and August,and mollusk Endopleura lubrica and polychaete Sigambra hanaokai were important contributors to these differences according to the results of the Similarity Percentages analysis.Suspended particulate matter(SPM)was identified as the primary driving factors of macrobenthic variability.In summary,the community structure underwent temporal changes influenced by complex current patterns,while biodiversity remained relatively stable.This study contributes to our understanding of the key environmental factors affecting macrobenthic communities and biodiversity.It also provides valuable data support for the long-term monitoring of macrobenthos and the environment in the Shengsi Archipelago.展开更多
This study selects geochemical data of basalts from different seamounts in the Mid-Pacific Mountains province and conducts analyses of major and trace elements as well as Sr-Nd-Pb isotopes to explore the tectonic evol...This study selects geochemical data of basalts from different seamounts in the Mid-Pacific Mountains province and conducts analyses of major and trace elements as well as Sr-Nd-Pb isotopes to explore the tectonic evolution,petrogenesis,and mantle-source magama characteristics of the Mid-Pacific Mountains.The basalts from the Mid-Pacific Mountains are predominantly alkali basalts,rich in alkalies,and changing in potassium.They exhibit geochemical features of ocean island basalts(OIB),with distinct fractionation between light and heavy rare-earth elements and a pronounced Ce negative anomaly(δ_(Ce)=0.16–1.10,average 0.84),along with enrichment in large ion lithophile elements(LILEs).The Mid-Pacific Mountains are intraplate ocean island basalts formed by mantle plume(hotspot)activity,originating mainly from an enriched mantle magma source region,and most of them have undergone low degree of partial melting and a certain degree of crystalline differentiation,with negligible contamination from oceanic crust materials.The Mid-Pacific Mountains exhibit ratios of^(87)Sr/^(86)Sr(i)(0.702733–0.704313,average 0.703452)and^(143)Nd/^(144)Nd(i)(0.512698–0.512996,average 0.512846)which are close to the HIMU mantle endmember,and ratios of 206Pb/204Pb(18.953–19.803),^(207)Pb/^(204)Pb(15.54–15.62)and^(208)Pb/^(204)Pb(38.813–39.514)which are close to the EMII mantle end-member.Combined with the isotopic geochemical characteristics in the West Pacific Seamounts province,the basalts from the Mid-Pacific Mountains were considered to represent a certain proportion of mixing mantle end-members between the HIMU and EMII,possibly formed by the mixing of the HIMU superplume in the South Pacific hotspot region with the EMII secondary mantle plume in the transition zone during their ascent.展开更多
Efficient segmentation of oiled pixels in optical remotely sensed images is the precondition of optical identification and classification of different spilled oils,which remains one of the keys to optical remote sensi...Efficient segmentation of oiled pixels in optical remotely sensed images is the precondition of optical identification and classification of different spilled oils,which remains one of the keys to optical remote sensing of oil spills.Optical remotely sensed images of oil spills are inherently multidimensional and embedded with a complex knowledge framework.This complexity often hinders the effectiveness of mechanistic algorithms across varied scenarios.Although optical remote-sensing theory for oil spills has advanced,the scarcity of curated datasets and the difficulty of collecting them limit their usefulness for training deep learning models.This study introduces a data expansion strategy that utilizes the Segment Anything Model(SAM),effectively bridging the gap between traditional mechanism algorithms and emergent self-adaptive deep learning models.Optical dimension reduction is achieved through standardized preprocessing processes that address the decipherable properties of the input image.After preprocessing,SAM can swiftly and accurately segment spilled oil in images.The unified AI-based workflow significantly accelerates labeled-dataset creation and has proven effective for both rapid emergency intelligence during spill incidents and the rapid mapping and classification of oil footprints across China’s coastal waters.Our results show that coupling a remote sensing mechanism with a foundation model enables near-real-time,large-scale monitoring of complex surface slicks and offers guidance for the next generation of detection and quantification algorithms.展开更多
The Argo program measures temperature and salinity in the upper ocean(0–2000 m).These observations are critical for weather/climate studies,ocean circulation analysis,and sea-level monitoring.To address the limitatio...The Argo program measures temperature and salinity in the upper ocean(0–2000 m).These observations are critical for weather/climate studies,ocean circulation analysis,and sea-level monitoring.To address the limitations of traditional thresholds in Argo data quality control(QC),this study proposes a novel probability distribution-based inference method(PDIM)for temperature-salinity threshold inference.By integrating historical observations with climatological data,the method utilizes historical data corresponding to latitude and longitude grids,calculates temperature/salinity frequency distributions for each depth,and determines“zero probability”boundaries through combined frequency distribution and climatology data.Then a probability distribution model is established to detect outliers automatically based on the features in the probability density function,which eliminates the traditional dependence on the normal distribution hypothesis.When applied to global Argo datasets from China Argo Real-time Data Center(CARDC),PDIM successfully identifies suspicious profiles and sensor drifts with high reliability,achieving a low false positive rate(0.55%for temperature,0.18%for salinity)while maintaining competitive true positive rate(28.29%for temperature,55.15%for salinity).This method is expected to improve the reliability of Argo data QC and has important significance for Argo QC.展开更多
Phytoplankton play a pivotal role in the Southern Ocean ecosystem.This study examines the phytoplankton community structure and the environmental factors driving it in the Cosmonaut Sea,based on samples collected usin...Phytoplankton play a pivotal role in the Southern Ocean ecosystem.This study examines the phytoplankton community structure and the environmental factors driving it in the Cosmonaut Sea,based on samples collected using a net during the summer of 2020/2021.We identified 99 phytoplankton species,predominantly comprising diatoms and dinoflagellates.Among these,diatoms-notably Pseudo-nitzschia,Chaetoceros,and Fragilariopsis,dominated the community in terms of species richness,abundance,and biomass.Endemic species of the Southern Ocean,such as Corethron pennatum,Proboscia alata,and Cylindrotheca closterium,also made significant contributions.Phytoplankton abundance and biomass showed similar spatial distribution patterns,with hotspots in the northern section of the survey area that gradually diminished towards the coastal regions.The oceanic area exhibited low phytoplankton diversity but pronounced regional variations in community distribution,with the northern region emerging as a key zone for abundance,biomass,and diversity.Nutrient distribution was identified as the primary environmental driver shaping the phytoplankton community,with silicate levels having a significant negative impact on overall phytoplankton abundance and the dominant species.展开更多
The turbidity maximum zone(TMZ)is a distinctive aquatic environment marked by consistently higher turbidity compared to upstream and downstream section.In the TMZ,physicochemical properties such as intense light limit...The turbidity maximum zone(TMZ)is a distinctive aquatic environment marked by consistently higher turbidity compared to upstream and downstream section.In the TMZ,physicochemical properties such as intense light limitation,abundant nutrients,and rapid salinity shifts play a crucial role in shaping phytoplankton dynamics.The Qiantang River estuary-Hangzhou Bay(QRE-HZB)is a macrotidal estuary system known for its exceptionally high suspended solids concentration.To investigate the impact of TMZ on the standing crop and size structure of phytoplankton in the QRE-HZB,we conducted three cruises in dry,wet,and dry-to-wet transition seasons during 2022-2023,by assessing parameters including size fractionated chlorophyll a(chl a),turbidity,Secchi depth,temperature,salinity,nutrients,and mesozooplankton.Results reveal significant variations in the TMZ and associated environmental factors in different periods,which markedly influenced the phytoplankton chl-a concentration,size structure,and cell activity(pheophytin/chl a).The chl-a concentration was high with micro-phytoplankton predominance in wet season,while nano-phytoplankton dominated in dry season.Within the TMZ,lower chl-a concentrations and pico-chl-a contributions,alongside higher pheophytin/chl-a and micro-chl-a contributions,were observed.The Spearman’s rank correlation and generalized additive model analyses indicated strong correlations of chl-a concentrations with turbidity,nutrients,and mesozooplankton.Redundancy analysis further revealed that salinity,nutrients,and turbidity significantly regulated variations in size structure.Phytoplankton mortality within the TMZ was primarily driven by high turbidity and salinity fluctuations,reflecting the vigorous resuspension and mixing of freshwater and seawater in the QRE-HZB.These findings highlight that the standing crop and size structure of phytoplankton were strongly regulated by the TMZ and associated physicochemical factors in the macrotidal QRE-HZB.展开更多
Recently, a coupled data assimilation system based on the community earth system model(CESM) and ensemble adjustment Kalman filter(EAKF) has been established to assimilate various ocean observations including gridded ...Recently, a coupled data assimilation system based on the community earth system model(CESM) and ensemble adjustment Kalman filter(EAKF) has been established to assimilate various ocean observations including gridded sea surface temperature and in situ temperature and salinity profiles for the initialization of seasonal prediction. The main goal of the present study is to assess the El Nino-Southern Oscillation(ENSO) prediction capability of the newly developed system(CESM-E). We compare it with a benchmark prediction system based on the same model but employing a nudging scheme(CESM-N), which nudged the wind fields and ocean temperature. Results have found that although the initial subsurface temperature are comparable in the two systems, CESM-E outperforms CESM-N in a few aspects. For example, CESM-E exhibits clearly lower root mean square errors in the first few leading months and higher anomaly correlation coefficients in the Nino4 region. In addition, case studies reveal that CESM-E is clearly better in predicting the 2006/2007 El Nino and 2010/2011 La Nina events. Reasons behind the improvement of CESME are studied, which can provide useful insights into the design of a data assimilation system and the further improvement of current ENSO prediction system.展开更多
Air-sea water vapor and CO_(2) flux observation experiments were carried out at the Yantai National Satellite Ocean Calibration Platform and the jetty at Monolithic Beach,Juehua Island,using a 100 Hz gas analyzer.The ...Air-sea water vapor and CO_(2) flux observation experiments were carried out at the Yantai National Satellite Ocean Calibration Platform and the jetty at Monolithic Beach,Juehua Island,using a 100 Hz gas analyzer.The observations were corrected by employing wild point rejection,linear detrending,delay correction,coordinate rotation,time matching,and Webb,Pearman,and Leuning(WPL)correction.The results of spectral analysis and a turbulence development adequacy data quality check showed that the overall observation data quality was good.The air-sea water vapor and CO_(2) flux results showed that the observation duration affected both the air-sea flux intensity and direction at different observation frequencies.At shorter observation durations,the air-sea flux values measured at 100 Hz were smaller than the 20 Hz measurements and had opposite directions.In addition,the WPL correction reduced the overall air-sea flux and partially minimized the effect of observation frequency on the air-sea flux intensity.These results showed that high-frequency observations showed more turbulence variations than low-frequency observations.This conclusion could promote an understanding of small-scale turbulence variations.展开更多
基金supported by the National High Technology Research and Development Program of China(863 Pro-gram, Grant No.2005AA615040)the National Natural Science Foundation of China(Grant No.40776038)+2 种基金Open Fund of Key Laboratory of Geo-detection(China University of Geosciences,Beijing),Ministry of Education (GrantNo. GDL0802)the Ocean Public Welfare Scientific Research Special Appropriation Project(Grant Nos.200805079and 200805005)the Open Fund of Key Laboratory of Submarine Geoscience,State Oceanic Administration(Grant No. KCSG0803)
文摘Compared with the laboratory acoustic measurement of sediment samples, the in-situ acoustic measurement in marine sediment is considered more accurate and rehable, because it covers all of the surrounding environment factors and avoids the disturbance during the course of sampling and transporting of sediment samples. A new multi-frequency in-situ geoacoustic measurement system （MFIS^AMS） has been developed. The system can provide acoustic vdocity （compressional wave） and attenuation profiles of the uppermost 4 - 8 m sediment in the seafloor. It consists of 8 channels with 12 frequencies （multi-frequencies） and 0.5 - 2 MHz sampling rates. The data collected can be transmiuted in real-time. Associated with inclinometer and altimeter, it can provide the data for depth emendation. Acoustic velocity and attenuation data have been obtained from two in-situ experiments conducted in the Hangzhou Bay.
基金funded by the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (GML2019ZD0307)the Marine Geological Survey Program of China Geological Survey (DD20190218, DD20221706)+1 种基金the Key Program of Marine Economy Development Special Foundation of Department of Natural Resources of Guangdong Province (GDNRC [2020] 043)the National Natural Science Foundation of China (41806074, 41730528)。
文摘Internal solitary waves(ISWs) contain great energy and have the characteristics of emergency and concealment. To avoid their damage to offshore engineering, a new generation of monitoring and early warning system for ISWs was developed using technologies of double buoys monitoring, intelligent realtime data transmission, and automatic software identification. The system was applied to the second natural gas hydrates(NGHs) production test in the Shenhu Area, South China Sea(SCS) and successfully provided the early warning of ISWs for 173 days(from October 2019 to April 2020). The abrupt changes in the thrust force of the drilling platform under the attack of ISWs were consistent with the early warning information, proving the reliability of this system. A total of 93 ISWs were detected around the drilling platform. Most of them occurred during the spring tides in October–December 2019 and April 2020, while few of them occurred in winter. As suggested by the theoretical model, the full-depth structure of ISWs was a typical current profile of mode-1, and the velocities of wave-induced currents can reach 80 cm/s and30 cm/s, respectively, in the upper ocean and near the seabed. The ISWs may be primarily generated from the interactions between the topography and semidiurnal tides in the Luzon Strait, and then propagate westward to the drilling platform. This study could serve as an important reference for the early warning of ISWs for offshore engineering construction in the future.
文摘In the numerical studies of a real tide M4 resonance system, the Xiangshan Port which is a partially-closed bay, Dong et al. [1999. Acta Oceanologica Sinica, 21 （3）： 1-6] found the interesting phenomenon that the advection plays an important role in inhibiting the growth of the amplitude of the tidal second-order resonance response （M4）. This result is contrary to the general traditional ideas for a non-resonance system. How this phenomenon is interpreted and what internal mechanism is behind the phenomenon are the main focuses of this study. The followings are examined： （1） the dynamic features of a second-order resonance system of tide; （2） the dominating factors on the second-order resonance responses; （3） the effects of both the friction and the advection on the second-order resonance responses; and （4） their roles in dominating the second-order resonance response and internal mechanisms by using the analytical methods. The respective results show that： （1） Both the bottom friction and the advection play significant roles in dominating the magnitude of the amplitude of the second-order resonance responses; （2） the effect of the friction on the second-order resonance response depends on the distribution ratio of the work-done of the system to friction force exhausted into between the damping of the first-order system and the inner excitation of the second-order system; （3） the advection plays a positive role in increasing the amplitude of the second-order non-resonance response in the second order non-resonance of tide; （4） in a second-order resonance system of tide, the effect of the advection may be either to increase or to decrease the amplitudes of the second-order resonance responses of tide, which depends on the distribution ratio mentioned above.
基金The National Polar Special Program under contract Nos IRASCC 01-01-02 and IRASCC 02-02the National Natural Science Foundation of China under contract Nos 41976228,42276255,41976227,42176227,and 42076243+1 种基金the International Cooperation Key Project of the Ministry of Science and Technology under contract No.2022YFE0136500the Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,under contract Nos JG2011,JG2211,JG2013,and JG1805.
文摘Polynyas and their adjacent seasonal ice zones(SIZs)represent the most productive regions in the Southern Ocean,supporting unique food webs that are highly sensitive to climate change.Understanding the dynamics of phytoplankton and the carbon pool in these areas is crucial for assessing the role of the Southern Ocean in global carbon cycling.During the late stage of an algal bloom,seawater samples at 14 stations were collected in the Amundsen Sea Polynya(ASP)and adjacent SIZ.Using nutrients,phytoplankton pigments,organic carbon(OC),remote sensing data,and physicochemical measurements,as well as CHEMTAX model simulations,we investigated the response of the phytoplankton crops,taxonomic composition,and OC pool to environmental factors.Our analyses revealed that hydrodynamic regimes of the polynya,adjacent SIZs and open sea were regulated by the regionally varying intrusion of Circumpolar Deep Water,photosynthetically active radiation and sea ice melt water.The ASP exhibited the highest seasonal nutrient utilization rates[ΔN=(1059±386)mmol/m^(2),ΔP=(50±17)mmol/m^(2) andΔSi=(956±904)mmol/m^(2)],while the open sea had lower rates.The integrated chlorophyll a(Chl a)concentration at depths of 0–200 m ranged from 20.4 mg/m^(2) to 1420.0 mg/m^(2) and peaked in the polynya.In the study area,Haptophytes Phaeocystis antarctica was the dominant functional group(34%±27%),and diatoms acted as a secondary contributor(23%±14%).The major functional group and particulate OC(POC)contributor varied from diatoms(36%±12%)in the open sea to haptophytes(48%±31%)in the polynya waters.Strong light conditions and microelement limitations promoted the dominance of P.antarctica(low Fe forms)dominance in the ASP.The strong correlations between the POC and Chl a depth-integrated concentration suggest that the POC was primarily derived from phytoplankton,while dissolved OC(DOC)was influenced by consumer activity and water mass transport.In addition,the transport of OC in the upper 200 m of the water column within the ASP was quantified,revealing the predominantly westward fluxes for both DOC[9.0 mg/(m^(2)·s)]and POC[7.2 mg/(m^(2)·s)].The latitudinal transport exhibited the northward transport of DOC[8.1 mg/(m^(2)·s)]and southward transport of POC[4.3 mg/(m^(2)·s)]movement.These findings have significant implications for enhancing our understanding of how hydrodynamics influence OC cycling in polynya regions.
基金The National Key Research and Development Program of China under contract No.2022YFE0136500the Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,under contract Nos JG2212 and JG2211+2 种基金the National Natural Science Foundation of China under contract Nos 42276255,41976228,and 42176227the National Polar Special Program“Impact and Response of Antarctic Seas to Climate Change”under contract Nos IRASCC 01-01-02 and IRASCC 02-02the China Scholarship Council under contract No.201704180017.
文摘The melting of seasonal sea ice in Antarctica plays a pivotal role in the region’s carbon cycle,influencing global carbon storage and the exchange of carbon between the atmosphere and the ocean.However,the impact of variability in the timing of seasonal sea ice retreat on the flux and composition of sinking particulate matter remains to be elucidated.In this study,we deployed sediment traps in Prydz Bay during the austral summers of 2019/2020 and 2020/2021,noting that sea ice melting occurred approximately one and a half months earlier in the former summer compared to the latter.We analyzed sediment trap data,which included total mass flux(TMF),particulate organic carbon(POC),biogenic silica(BSi),particulate inorganic carbon,and lithogenic particle(Litho)fluxes,as well as the stable isotopesδ^(13)C andδ^(15)N of particulate organic matter(POM).Additionally,we incorporated remote sensing data on sea ice concentration and chlorophyll a.This dramatic delay in sea ice melting timing could result in a significant increase in TMF,BSi and POC fluxes in the summer of 2020/2021 compared to 2019/2020.Elevated BSi fluxes and more ^(13)C-depleted POC in the austral summer of 2020/2021 suggest that the delayed melting of sea ice may have stimulated the productivity of centric diatoms.Furthermore,the higher BSi/POC ratio and more negativeδ^(15)N values of POM,along with a reduced presence of krill in the traps,indicate a diminished grazing pressure from zooplankton,which collectively enhanced the sedimentation efficiency of POC during the austral summer of 2020/2021.These findings highlight the critical role of sea ice melting timing in regulating productivity,flux and composition of sinking particulate matter in the Prydz Bay ecosystem,with significant implications for carbon cycling in polar oceans.
基金The National Natural Science Foundation of China under contract No.41906193the Scientific Research Foundation of Third Institute of Oceanography,Ministry of Natural Resources,under contract No.2019033+2 种基金the Natural Science Foundation of Fujian Province under contract No.2019J05147the Federal Ministry of Education and Research of Germany under contract No.FKZ 03F03F0783Athe National Polar Special Program under contract Nos IRASCC 01-01-02 and IRASCC 02-02.
文摘The global ocean is a major source of the climate-relevant atmospheric trace gas nitrous oxide(N_(2)O).However,an accurate assessment of the global oceanic emissions of N_(2)O is hampered by missing data on dissolved N_(2)O from large regions such as the Southern Ocean.To address this deficit,N_(2)O was measured in the Prydz Bay in February 2015 during the 31st Chinese National Antarctic Research Expedition.N_(2)O concentrations(saturation)in the surface layer were generally low(undersaturation with respect to atmospheric equilibrium)and ranged from 13.3 nmol/L to 16.1 nmol/L(83%–102%)at the time of sampling.A comparison of our observations with archived data revealed that no discernible trend in N_(2)O concentrations in the surface waters of Prydz Bay could be detected for the period between 2006 and 2015.Temperature and salinity changes driven by meltwater input were the predominant controls on N_(2)O concentrations in surface waters.At depth,the distribution of N_(2)O concentrations was dominated by production via nitrification in offshore deep waters and vertical convection in the shelf waters,where concentrations were lower and gradients were less steep.Our results suggest a rather unusual pattern of N_(2)O distribution in the Prydz Bay(low N_(2)O in shelf waters compared with the open ocean),providing important insights into the coastal dynamics of N_(2)O in high-latitude polar regions.
基金The National Natural Science Foundation of China under contract Nos 42276255,41976228,42176227 and 42306262the National Polar Special Program under contract Nos IRASCC 01-01-02,IRASCC 02-02-03,and IRASCC 02-02-05the Scientific Research Fund of the Second Institute of Oceanography under contract Nos JG2211 and JG2212.
文摘Dissolved organic carbon(DOC)constitutes the largest organic carbon reservoir in the ocean and plays a vital role in the oceanic carbon cycle.However,research on DOC in Antarctica has been limited,largely due to difficulties in sample collection.In this study,we investigate chromophoric dissolved organic matter(CDOM)in the Cosmonaut Sea and Cooperation Sea,Antarctica.The relative abundances of CDOM,as indicated by the absorption coefficient at 254 nm(a_(254)),exhibit significant variability,ranging from 1.29 m^(-1) to 8.37 m^(-1).The diatom species B is the primary contributor to CDOM in the region influenced by the Antarctic slope current.Using excitation-emission matrix fluorescence spectroscopy coupled with parallel factor analysis(EEM-PARAFAC),we identify three fluorescent components:one protein-like component(C1)and two humic-like components(C2 and C3).Our findings indicate that strong microbial activity in the euphotic zones of the Cosmonaut Sea and Cooperation Sea serves as a primary pathway for the removal of protein-like substances while also acting as a significant source of humic-like substances.Microbial degradation likely accounts for the decoupling of the vertical distribution of DOC and phytoplankton.Furthermore,the intrusion of modified circumpolar deep water(mCDW)into the euphotic zones of open ocean areas influences the distribution of CDOM at depths shallower than 200 m.These results have important implications for enhancing our understanding of the dynamics of CDOM and DOC in east Antarctica,as well as for improving assessments of the carbon cycle.
基金Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LZJMD24D050002)Natural Science Foundation of Zhejiang Province(LZJMZ23D050001,LGF22D050007,LGF19D050001)Zhejiang Province Meteor-ological Science Foundation(2022ZD07)。
文摘This study examines the multi-scale spatio-temporal evolution of drought characteristics in Zhejiang Province.We propose a comprehensive index to identify drought days and events by incorporating three widely used monitoring indices:the precipitation anomaly percentage,relative humidity index,and standardized precipitation index.The analysis reveals a significant long-term decreasing trend in the frequency of drought days across Zhejiang Province from 1971 to 2020,with a total of 170 drought events being identified.An Empirical Orthogonal Function(EOF)analysis of precipitation anomalies during these events reveals a dominant province-wide monopole mode,alongside a secondary northsouth inverse dipole,a third tripole,and a fourth southwest-northeast inverse dipole.Furthermore,a composite analysis of the drought events demonstrates a widespread increase in temperature across all stations,with a strong spatial correspondence between the temperature anomalies and their associated frequency.The study identifies 21 extreme drought events,characterized by spatially inconsistent precipitation patterns across the entire province.
基金Supported by the Pioneer and Leading Goose R&D Program of Zhejiang(No.2023C03130)the National Key R&D Program of China(No.2019YFD0901101)+4 种基金the National Natural Science Foundation of China(No.42076169)the Oceanic Interdisciplinary Program of Shanghai Jiao Tong University(Nos.SL2022ZD203,SL2022MS012)the Zhejiang Provincial Natural Science Founds for Distinguished Young Scientists(No.LR21D060001)the State Key Laboratory of Satellite Ocean Environment Dynamics(No.SOEDZZ1902)the ChinaAPEC Cooperation Fund(No.2029901)。
文摘Microplastics(MPs)have garnered significant international scrutiny as an emerging environmental pollutant,constituting one of the four principal global environmental threats and posing potential health hazards to humans.However,data on the impact of MPs on the early life of the commercially important fish remain limited.In this study,polystyrene microspheres(PS-MPs)(1 and 5μm)were used to investigate the effects of MPs on the growth,development,and metabolism in early life stages of large yellow croaker Pseudosciaena crocea.Results indicate that MPs were enriched in the gastrointestinal tract and gills of the fish.In addition,PS-MPs(1μm)exhibited no obvious effects on embryo hatching and heart rates,while increased the mortality rate(23.00%vs.control 14.99%)and decreased the body length(4098.61±447.03μm vs.control with 2827.04±254.75μm)of the larvae at the highest exposure concentration(5×10^(4)items/L).Metabolomics analysis revealed that PS-MPs(5μm)induced mild perturbations in phospholipid metabolism,specifically alterations in phosphatidylethanolamine(PE)levels.These changes influenced the cell membranes of juvenile fish,and consequently elicited inflammatory responses,disrupted lipid homeostasis,and affected other critical physiological processes.Ultimately,these effects may avoid the growth retardation and potential mortality.Therefore,PS-MPs could affect negatively the fish health in the early life stage,which has implications for aquatic ecosystems.
基金supported by the National Science Foundation of China(Grant no.42376064)the Chinese Polar Environment Comprehensive Investigation&Assessment Programs(Grant no.CHINARE 2016-03-02).
文摘Understanding the sediment record during the Little Ice Age(LIA)can help elucidate natural sea ice fluctuation and carbon cycle variability.This study analyzed the grain size composition(including ice-rafted debris),total organic carbon(TOC),total nitrogen(TN)content,and stable isotopic composition(δ13C andδ15N)of the sediment record(approximately 490 a)of core ARC7-R11 in the northern part of the Chukchi Shelf.The sediment grains comprise mostly(>90%)silt and clay components.The grain size composition suggests generally low-energy hydrodynamic conditions across the region,yet reveals a trend of enhancement in hydrodynamics from the bottom to top layers of the sediment core,particularly after the 1940s.It also shows occurrences of seasonal sea ice and retreat of the perennial sea ice margin during warmer periods of the LIA and the post-LIA period.The organic matter content is high throughout the core,with heavierδ13C values and moderate TOC/TN ratios indicating primarily marine origin;the terrestrial input is<37.5%according to the endmember model.The variation trend of marine-derived organic carbon(OC)content is similar to that of summer temperature anomalies;while variation trend of terrestrially derived OC shows significant correlation with that of the number of ice-free days in the southern shelf region,except for the period from approximately 1700s to the 1870s.During the LIA,the TOC content fluctuated and decreased,and the relative contribution of terrestrial OC was higher than during the modern warm period.The amount of OC buried in the sediment has increased with climate warming,especially after the 1940s,reflecting the enhanced ability of sediment to sequester carbon during warmer periods.
基金Supported by the National Key Research and Development Program of China(No.2022YFC2806805)the National Natural Science Foundation of China(Nos.42076122,42306130)the Digital Deep-sea Typical Habitats Program of China Deep Ocean Affairs Administration(No.DYXZ-02)。
文摘Understanding the seasonal variations of the zooplankton community’s structure in the Western Pacific Warm Pool(WPWP)-the most stable open marine environment in the Pacific Ocean-is crucial to predict the impacts of climate change on the ecosystem.However,knowledge on these variations in this region down to the mesopelagic zone is insufficient.In this study,the environmental DNA(eDNA)metabarcoding method was used to investigate the zooplankton community during summer,autumn,and winter,from the surface to a depth of 1000 m spanning the epipelagic to mesopelagic zones.The zooplankton community structure exhibited seasonal fluctuations at multiple depths except for 200 and 1000 m.In addition,a stronger zooplankton seasonality was particularly recorded in the epipelagic zone than in the mesopelagic zone,which is consistent with the environmental changes.The studied zooplanktons are dominated by medusae and copepods that showed distinct seasonality.At all depths,medusae exhibited greater seasonal variations than the overall zooplankton community,whereas the copepods did not exhibit significant seasonality.The environmental features and the seasons exerted greater influences on the structure of the zooplankton communities than did the spatial factors.The results of this study indicate that eDNA metabarcoding can provide novel insights into zooplankton assemblages due to its ability to capture a rich variety of medusae,which are often underestimated by net collection.
基金The fund from Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)under contract No.SML2021SP310the National Natural Science Foundation of China under contract Nos 42227901 and 42475061the Key R&D Program of Zhejiang Province under contract No.2024C03257.
文摘The inherent asymmetry and diversity of the El Niño-Southern Oscillation(ENSO)pose substantial challenges to its prediction.Potential predictability measures the upper limit of predictability for a certain event.Assessing the potential predictability of ENSO across varying phases and intensities with sophisticated climate models is crucial for understanding the upper limits of forecasting capabilities and identifying room for future enhancement.Based on the hindcast dataset with a recently developed ensemble forecasting system(the community earth system model,CESM),this study comprehensively investigates potential predictability for ENSO across different phases and intensities.The findings reveal that La Niña events possess higher potential predictability relative to their El Niño counterparts.Strong events exhibit significantly higher potential predictability than weak events within the same phase.The potential predictability of distinct ENSO types is primarily influenced by the seasonal variation inherent to their predictability.Regardless of the event classification,the potential predictability is characterized by a rapid decline from spring onwards,with the apex of this decline occurring in summer.The intensity of the seasonal predictability barrier inversely correlates with the upper limit of potential predictability.Specifically,a weaker(stronger)seasonal barrier is associated with a higher(lower)potential predictability.In addition,there is significant interdecadal variability both in the predictability of warm and cold ENSO events.The potential predictability for La Niña events decreases more slowly with increasing lead months,particularly in recent decades,resulting in an overall higher upper limit of potential predictability for La Niña events than for El Niño events over the past century.Nevertheless,El Niño events have also maintained a high potential predictability.This suggests substantial potential for improvement in future prediction for both.
基金The Scientific Research Fund of the Second Institute of Oceanography,Ministry of Natural Resources,China under contract Nos SZ2302 and JG2209.
文摘Macrobenthic organisms are commonly employed as biomonitors for environmental risk assessment.In this study,we aimed to investigate the spatial and temporal patterns of the macrobenthic community,which is influenced by environmental factors of sediments and bottom water layer.We sampled a total of 12,11,10,and 11 stations in the Shengsi Archipelago during June 2010,August 2010,November 2020,and April 2021 respectively.A total of 124 species of macrobenthos were identified,with polychaetes being the dominant group.The abundance,biomass,and diversity indices exhibited no significant temporal differences.Similarly,biodiversity did not exhibit a clear spatial gradient,likely due to the small study area and the absence of significant differences in key factors such as depth.However,the stations with the lowest biodiversity values consistently appeared in the southwest region,possibly due to the impact of human activities.Significant differences in the macrobenthic community were observed between all months except between June and August,and mollusk Endopleura lubrica and polychaete Sigambra hanaokai were important contributors to these differences according to the results of the Similarity Percentages analysis.Suspended particulate matter(SPM)was identified as the primary driving factors of macrobenthic variability.In summary,the community structure underwent temporal changes influenced by complex current patterns,while biodiversity remained relatively stable.This study contributes to our understanding of the key environmental factors affecting macrobenthic communities and biodiversity.It also provides valuable data support for the long-term monitoring of macrobenthos and the environment in the Shengsi Archipelago.
基金Supported by the National Natural Science Foundation of China(No.U2244222).
文摘This study selects geochemical data of basalts from different seamounts in the Mid-Pacific Mountains province and conducts analyses of major and trace elements as well as Sr-Nd-Pb isotopes to explore the tectonic evolution,petrogenesis,and mantle-source magama characteristics of the Mid-Pacific Mountains.The basalts from the Mid-Pacific Mountains are predominantly alkali basalts,rich in alkalies,and changing in potassium.They exhibit geochemical features of ocean island basalts(OIB),with distinct fractionation between light and heavy rare-earth elements and a pronounced Ce negative anomaly(δ_(Ce)=0.16–1.10,average 0.84),along with enrichment in large ion lithophile elements(LILEs).The Mid-Pacific Mountains are intraplate ocean island basalts formed by mantle plume(hotspot)activity,originating mainly from an enriched mantle magma source region,and most of them have undergone low degree of partial melting and a certain degree of crystalline differentiation,with negligible contamination from oceanic crust materials.The Mid-Pacific Mountains exhibit ratios of^(87)Sr/^(86)Sr(i)(0.702733–0.704313,average 0.703452)and^(143)Nd/^(144)Nd(i)(0.512698–0.512996,average 0.512846)which are close to the HIMU mantle endmember,and ratios of 206Pb/204Pb(18.953–19.803),^(207)Pb/^(204)Pb(15.54–15.62)and^(208)Pb/^(204)Pb(38.813–39.514)which are close to the EMII mantle end-member.Combined with the isotopic geochemical characteristics in the West Pacific Seamounts province,the basalts from the Mid-Pacific Mountains were considered to represent a certain proportion of mixing mantle end-members between the HIMU and EMII,possibly formed by the mixing of the HIMU superplume in the South Pacific hotspot region with the EMII secondary mantle plume in the transition zone during their ascent.
基金The National Natural Science Foundation of China under contract No.42371380the National Key Research and Development Program of China under contract No.2023YFC2811800the Fundamental Research Funds for the Central Universities under contract No.0904-14380035.
文摘Efficient segmentation of oiled pixels in optical remotely sensed images is the precondition of optical identification and classification of different spilled oils,which remains one of the keys to optical remote sensing of oil spills.Optical remotely sensed images of oil spills are inherently multidimensional and embedded with a complex knowledge framework.This complexity often hinders the effectiveness of mechanistic algorithms across varied scenarios.Although optical remote-sensing theory for oil spills has advanced,the scarcity of curated datasets and the difficulty of collecting them limit their usefulness for training deep learning models.This study introduces a data expansion strategy that utilizes the Segment Anything Model(SAM),effectively bridging the gap between traditional mechanism algorithms and emergent self-adaptive deep learning models.Optical dimension reduction is achieved through standardized preprocessing processes that address the decipherable properties of the input image.After preprocessing,SAM can swiftly and accurately segment spilled oil in images.The unified AI-based workflow significantly accelerates labeled-dataset creation and has proven effective for both rapid emergency intelligence during spill incidents and the rapid mapping and classification of oil footprints across China’s coastal waters.Our results show that coupling a remote sensing mechanism with a foundation model enables near-real-time,large-scale monitoring of complex surface slicks and offers guidance for the next generation of detection and quantification algorithms.
基金The National Key Research and Development Program of China under contract No.2021YFC3101503the Hunan Provincial Natural Science Foundation of China under contract No.2023JJ10053+1 种基金the National Natural Science Foundation of China under contract Nos 42276205 and 42406195the Youth Independent Innovation Science Foundation under contract No.ZK24-54.
文摘The Argo program measures temperature and salinity in the upper ocean(0–2000 m).These observations are critical for weather/climate studies,ocean circulation analysis,and sea-level monitoring.To address the limitations of traditional thresholds in Argo data quality control(QC),this study proposes a novel probability distribution-based inference method(PDIM)for temperature-salinity threshold inference.By integrating historical observations with climatological data,the method utilizes historical data corresponding to latitude and longitude grids,calculates temperature/salinity frequency distributions for each depth,and determines“zero probability”boundaries through combined frequency distribution and climatology data.Then a probability distribution model is established to detect outliers automatically based on the features in the probability density function,which eliminates the traditional dependence on the normal distribution hypothesis.When applied to global Argo datasets from China Argo Real-time Data Center(CARDC),PDIM successfully identifies suspicious profiles and sensor drifts with high reliability,achieving a low false positive rate(0.55%for temperature,0.18%for salinity)while maintaining competitive true positive rate(28.29%for temperature,55.15%for salinity).This method is expected to improve the reliability of Argo data QC and has important significance for Argo QC.
基金funded by National Science Foundation of China(Grant no.42276238)Impact and Response of Antarctic Seas to Climate Change(Grant nos.IRASCC 01-02-01D,01-01-02A)Taishan Scholars Program.
文摘Phytoplankton play a pivotal role in the Southern Ocean ecosystem.This study examines the phytoplankton community structure and the environmental factors driving it in the Cosmonaut Sea,based on samples collected using a net during the summer of 2020/2021.We identified 99 phytoplankton species,predominantly comprising diatoms and dinoflagellates.Among these,diatoms-notably Pseudo-nitzschia,Chaetoceros,and Fragilariopsis,dominated the community in terms of species richness,abundance,and biomass.Endemic species of the Southern Ocean,such as Corethron pennatum,Proboscia alata,and Cylindrotheca closterium,also made significant contributions.Phytoplankton abundance and biomass showed similar spatial distribution patterns,with hotspots in the northern section of the survey area that gradually diminished towards the coastal regions.The oceanic area exhibited low phytoplankton diversity but pronounced regional variations in community distribution,with the northern region emerging as a key zone for abundance,biomass,and diversity.Nutrient distribution was identified as the primary environmental driver shaping the phytoplankton community,with silicate levels having a significant negative impact on overall phytoplankton abundance and the dominant species.
基金Supported by the National Key Research and Development Program of China(No.2021 YFC 3101702)the Key R&D Program of Zhejiang(No.2022 C 03044)+2 种基金the Scientific Research Fund of the Second Institute of Oceanography,MNR(No.JG 1521)the Project of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography(No.SOEDZZ 2202)the National Program on Global Change and Air-Sea Interaction(Phase Ⅱ)-Hypoxia and Acidification Monitoring and Warning Project in the Changjiang River estuary,and Long-term Observation and Research Plan in the Changjiang River estuary and Adjacent East China Sea(LORCE)Project(No.SZ 2001)。
文摘The turbidity maximum zone(TMZ)is a distinctive aquatic environment marked by consistently higher turbidity compared to upstream and downstream section.In the TMZ,physicochemical properties such as intense light limitation,abundant nutrients,and rapid salinity shifts play a crucial role in shaping phytoplankton dynamics.The Qiantang River estuary-Hangzhou Bay(QRE-HZB)is a macrotidal estuary system known for its exceptionally high suspended solids concentration.To investigate the impact of TMZ on the standing crop and size structure of phytoplankton in the QRE-HZB,we conducted three cruises in dry,wet,and dry-to-wet transition seasons during 2022-2023,by assessing parameters including size fractionated chlorophyll a(chl a),turbidity,Secchi depth,temperature,salinity,nutrients,and mesozooplankton.Results reveal significant variations in the TMZ and associated environmental factors in different periods,which markedly influenced the phytoplankton chl-a concentration,size structure,and cell activity(pheophytin/chl a).The chl-a concentration was high with micro-phytoplankton predominance in wet season,while nano-phytoplankton dominated in dry season.Within the TMZ,lower chl-a concentrations and pico-chl-a contributions,alongside higher pheophytin/chl-a and micro-chl-a contributions,were observed.The Spearman’s rank correlation and generalized additive model analyses indicated strong correlations of chl-a concentrations with turbidity,nutrients,and mesozooplankton.Redundancy analysis further revealed that salinity,nutrients,and turbidity significantly regulated variations in size structure.Phytoplankton mortality within the TMZ was primarily driven by high turbidity and salinity fluctuations,reflecting the vigorous resuspension and mixing of freshwater and seawater in the QRE-HZB.These findings highlight that the standing crop and size structure of phytoplankton were strongly regulated by the TMZ and associated physicochemical factors in the macrotidal QRE-HZB.
基金The National Natural Science Foundation of China under contract Nos 42450178 and 42176003。
文摘Recently, a coupled data assimilation system based on the community earth system model(CESM) and ensemble adjustment Kalman filter(EAKF) has been established to assimilate various ocean observations including gridded sea surface temperature and in situ temperature and salinity profiles for the initialization of seasonal prediction. The main goal of the present study is to assess the El Nino-Southern Oscillation(ENSO) prediction capability of the newly developed system(CESM-E). We compare it with a benchmark prediction system based on the same model but employing a nudging scheme(CESM-N), which nudged the wind fields and ocean temperature. Results have found that although the initial subsurface temperature are comparable in the two systems, CESM-E outperforms CESM-N in a few aspects. For example, CESM-E exhibits clearly lower root mean square errors in the first few leading months and higher anomaly correlation coefficients in the Nino4 region. In addition, case studies reveal that CESM-E is clearly better in predicting the 2006/2007 El Nino and 2010/2011 La Nina events. Reasons behind the improvement of CESME are studied, which can provide useful insights into the design of a data assimilation system and the further improvement of current ENSO prediction system.
基金The National Key Research and Development Program of China under contract Nos 2022YFC3104203 and 2018YFC0213103the Science Foundation of Donghai Laboratory under contract No.DH-2022KF01019+1 种基金the National Natural Science Foundation under contract No.419061522023 Shanghai Education Science Research Project under contract No.C2023120.
文摘Air-sea water vapor and CO_(2) flux observation experiments were carried out at the Yantai National Satellite Ocean Calibration Platform and the jetty at Monolithic Beach,Juehua Island,using a 100 Hz gas analyzer.The observations were corrected by employing wild point rejection,linear detrending,delay correction,coordinate rotation,time matching,and Webb,Pearman,and Leuning(WPL)correction.The results of spectral analysis and a turbulence development adequacy data quality check showed that the overall observation data quality was good.The air-sea water vapor and CO_(2) flux results showed that the observation duration affected both the air-sea flux intensity and direction at different observation frequencies.At shorter observation durations,the air-sea flux values measured at 100 Hz were smaller than the 20 Hz measurements and had opposite directions.In addition,the WPL correction reduced the overall air-sea flux and partially minimized the effect of observation frequency on the air-sea flux intensity.These results showed that high-frequency observations showed more turbulence variations than low-frequency observations.This conclusion could promote an understanding of small-scale turbulence variations.
