Analysis of ocean fronts＇ uncertainties indicates that they result from indiscemibility of their spatial position and fuzziness of their intensity. In view of this, a flow hierarchy for uncertainty representation of ...Analysis of ocean fronts＇ uncertainties indicates that they result from indiscemibility of their spatial position and fuzziness of their intensity. In view of this, a flow hierarchy for uncertainty representation of ocean fronts is proposed on the basis of fuzzy-rough set theory. Firstly, raster scanning and blurring are carried out on an ocean front, and the upper and lower approximate sets, the indiscernible relation in fuzzy-rough theories and related operators in fuzzy set theories are adopted to represent its uncertainties, then they are classified into three sets： with members one hundred percent belonging to the ocean front, belonging to the ocean front＇s edge and definitely not belonging to the ocean front. Finally, the approximate precision and roughness degree are utilized to evaluate the ocean front＇s degree of uncertainties and the precision of the representation. It has been proven that the method is not only capable of representing ocean fronts＇ uncertainties, but also provides a new theory and method for uncertainty representation of other oceanic phenomena.展开更多
The oceanic mixed layer in the Southern Ocean is characterized by numerous fronts due to the stirring of freshwater influxes arising from ice melting.The interaction of these fronts with winds modulates the evolution ...The oceanic mixed layer in the Southern Ocean is characterized by numerous fronts due to the stirring of freshwater influxes arising from ice melting.The interaction of these fronts with winds modulates the evolution of the mixed layer and affects atmosphere−ocean energy exchanges.However,the underlying mechanism behind the wind-front interaction remains obscure due to a lack of three-dimensional observations of the ocean,particularly in terms of velocities.To address this issue,this study investigates the dynamics of fronts within the mixed layer during a storm by employing a subset of the global submesoscale-permitting simulation,Northeast Weddell Sea Pre-SWOT Level-4 Hourly MITgcm LLC4320 Native Grid 2km Oceanographic Dataset(ROAM_MIZ).We first compare the ROAM_MIZ data to glider data to assess the performance of the model simulation and find that the ROAM_MIZ can,to a large degree,capture sub-mesoscale features within a mixed layer.Subsequent analyses based on a subset of ROAM_MIZ show that lateral density gradients within the mixed layer rapidly decrease during high winds associated with the storm.Down-front winds accelerate this process as the Ekman buoyancy transport responsible for enhancing the instability of the fronts is primarily dominated by horizontal baroclinic components.After the storm,the fronts strengthen again in the presence of weaker winds due to the frontogenesis by the larger-scale strain.Moreover,the non-geostrophic turbulence induces a modification of the relative vorticity,affecting the instability within the mixed layer.These findings offer valuable guidance for the deployment of observational instruments and subsequent analysis,as well as deepen the understanding of air−sea interactions in the Southern Ocean.展开更多
On July 2^(nd),2025,32 scientists representing 15 countries gathered at Tartu,Estonia to make on-site endorsements for the Global ONCE(Ocean Negative Carbon Emissions)Program at the 12th INTECOL Wetlands Conference.Th...On July 2^(nd),2025,32 scientists representing 15 countries gathered at Tartu,Estonia to make on-site endorsements for the Global ONCE(Ocean Negative Carbon Emissions)Program at the 12th INTECOL Wetlands Conference.This marks a significant milestone for ONCE in establishing a systematic framework for coastal wetland carbon sequestration research and global collaboration(Figs.1,2).Coastal wetlands are critical transition zones linking terrestrial and marine ecosystems,yet they face severe degradation from anthropogenic land-based activities and sea level rise that propagate impacts to the ocean.As a UN Ocean Decade Program,the Global ONCE Program champions interdisciplinary and cross-regional collaboration to enhance carbon sequestration in the ocean and coastal wetlands through science and innovation.Aligned with the Tartu Declaration on Wetlands that includes resolutions to promote the rights of global wetlands(especially peatlands)and advance the discipline of wetland science based on facts,this initiative addresses key knowledge gaps in land-ocean interactions.The goal is to harness the full potential of coastal wetlands and ocean systems for climate mitigation,thereby laying a scientific foundation for international policy formulation and implementation.展开更多
The IUGG Associations for Atmosphere,Oceans and Cryosphere—IAMAS,IAPSO and IACS—held a Joint Scientific Assembly in Busan,South Korea,from 20 to 25 July 2025.This was the first joint assembly of all three associatio...The IUGG Associations for Atmosphere,Oceans and Cryosphere—IAMAS,IAPSO and IACS—held a Joint Scientific Assembly in Busan,South Korea,from 20 to 25 July 2025.This was the first joint assembly of all three associations since 2009,when they met in Montreal,Canada.It was the first time any of the associations had been hosted in Korea,and it had been two decades since any of them had met in Asia.The choice of Busan as the venue supported high levels of participation and smooth conference operations.The Local Organizing Committee,chaired by Prof.Kyung-Ja Ha of Pusan National University,oversaw the successful organization of the event.The assembly brought together 1725 participants in total,including 1282 researchers and 443 invited participants and individuals involved in side events,exhibitions,media coverage,and volunteer work.Participants came from 46 countries across Asia,Europe,North America,South America,Africa,and Oceania.IAMAS had 736 participants,IAPSO 321,and IACS 225.Survey data from 951 respondents revealed that Early Career Scientists,defined as those within 10 years of receiving their PhD,accounted for approximately 25%of participants.The demographic profile skewed young,with 66%of attendees in their 20s and 30s.The scientific program was organized by Prof.Seon-Ki Park(Chair),the Secretaries General from all three Associations,and the Local Organizing Committee.Reflecting the theme“Our Interconnected Earth,”the scientific program emphasized integrated approaches to climate systems,addressing climate change and environmental challenges through collaborative,transdisciplinary research.展开更多
Prydz Bay,East Antarctica,is a critical region for studying ocean–sea ice–ice shelf interactions and their role in the global climate system.This review synthesizes the advancements in numerical modeling of physical...Prydz Bay,East Antarctica,is a critical region for studying ocean–sea ice–ice shelf interactions and their role in the global climate system.This review synthesizes the advancements in numerical modeling of physical oceanographic processes in Prydz Bay,highlighting the evolution from early one-dimensional thermodynamic models to contemporary high-resolution,three-dimensional coupled ocean–sea ice–ice shelf frameworks.We discuss key milestones in understanding processes such as frazil ice dynamics and its impact on the basal mass balance of the Amery Ice Shelf,the pathways and mechanisms of Modified Circumpolar Deep Water intrusions,and the dynamic influences of large icebergs on regional circulation.Despite significant progress,challenges remain in integrating multi-component interactions and achieving long-term,high-resolution climate projections.Future efforts should focus on developing fully coupled models that incorporate atmosphere–ocean–sea ice–ice shelf–iceberg interactions,supported by enhanced observational networks and improved computational efficiency.This review underscores the importance of continued modeling advancement to better predict the responses of Antarctic ice shelves and polar climate to global change.展开更多
Atmospheric carbon dioxide(CO_(2))levels are escalating at an unprecedented rate,leading to the phenomenon of ocean acidification(OA).Parental exposure to acidification has the potential to enhance offspring resilienc...Atmospheric carbon dioxide(CO_(2))levels are escalating at an unprecedented rate,leading to the phenomenon of ocean acidification(OA).Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity.In this study,we analyzed larval growth and transcriptomic profiles in the Pacific oyster,Crassostrea gigas,a species of significant ecological relevance,under both control and elevated CO_(2)conditions experienced by their parental generation.Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage,followed by accelerated growth at the eyed stage.Through a comparative transcriptomic investigation of eyed larvae(25 d after fertilization),we observed that parental exposure to OA substantially influenced the gene expression in the offspring.Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure,potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors.These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.展开更多
This study investigates the vertical variations of aerosol size distribution (0.06–1µm) and cloud condensation nuclei(CCN) spectra over the Southern Ocean (SO) using aircraft observations from the SOCRATES campa...This study investigates the vertical variations of aerosol size distribution (0.06–1µm) and cloud condensation nuclei(CCN) spectra over the Southern Ocean (SO) using aircraft observations from the SOCRATES campaign.Results reveal a bimodal aerosol size distribution within the marine boundary layer (MBL),with peaks at diameters of~0.06µm and~0.65µm,dominated by sea-salt particles.Accumulation-mode aerosol concentrations decrease with altitude within the MBL,while Aitken-mode aerosol concentrations peak above the MBL (~2–3 km).Wind speed strongly correlates with coarse-mode aerosol concentration (R2=0.77),implicating sea spray as a major CCN source at low supersaturations (SS=0.1%).The altitudes of CCN concentration peaks shift from the MBL (<1 km,SS<0.4%) to the free troposphere (~2.5 km,SS>0.4%),suggesting new particle formation aloft,distinct from sea surface sources.These findings highlight the unique aerosol–CCN dynamics in the pristine SO,offering critical constraints for models simulating cloud–aerosol interactions in preindustrial-like environments.展开更多
The eddies in the southernmost southern Indian Ocean exert major dynamical and biogeochemical influences on the Earth system.Therefore,disentangling the relative contributions of vertical pumping and horizontal transp...The eddies in the southernmost southern Indian Ocean exert major dynamical and biogeochemical influences on the Earth system.Therefore,disentangling the relative contributions of vertical pumping and horizontal transport to water-property anomalies in the eddy cores is of fundamental importance.Here,the authors introduce a temperaturesalinity gradient-ratio approach(the"R-method")that compares vertical and meridional gradients to quantitatively separate the two processes.Application of the R-method to three-dimensional Argo observations reveals that horizontal transport,rather than vertical pumping,predominantly governs the observed temperature and salinity anomalies within eddy cores in the SIO.Independent theoretical estimations based on background meridional gradients,together with composites formed on isopycnal surfaces,further corroborate this conclusion.The results challenge the conventional assumption that vertical pumping invariably controls eddy-core property anomalies and demonstrate the utility of the R-method for diagnosing eddy impacts in climate and biogeochemical studies.展开更多
The present study compares the Atlantic Meridional Overturning Circulation(AMOC)in the North Atlantic from two simulations by an oceanic general circulation model with 1°×1°and 0.1°×0.1°r...The present study compares the Atlantic Meridional Overturning Circulation(AMOC)in the North Atlantic from two simulations by an oceanic general circulation model with 1°×1°and 0.1°×0.1°resolution,respectively,which explores the sensitivity of AMOC to the resolution.The ocean model is the latest version of the LASG/IAP Climate System Model(LICOM3),and it is forced with atmospheric data from phase 2 of the Ocean Model Intercomparison Project(OMIP2).Comprehensive comparison between the two simulations indicates that the simulated AMOC is highly sensitive to the spatial resolution.The high-resolution model(LICOM-H)simulates a deeper mixed-layer depth(MLD),due to increased surface salinity,than that in the low-resolution model(LICOML)in the Labrador Sea,and it also has stronger AMOC strength(the maximum climatic mean AMOC from 1958 to 2018 is 23.4 Sv for LICOM-H and 21.2 Sv for LICOM-L)and larger variability of AMOC index(2.3 Sv for LICOM-H and 1.7 Sv for LICOM-L).These differences can mainly be attributed to two main dynamic processes that benefit from high resolution.Firstly,LICOM-H can simulate much stronger boundary currents(~0.6 m s^(-1))than LICOM-L(0.3 m s^(-1))in the upper ocean,which leads to saltier and warmer seawater being transported to the Labrador Sea,where it enhances deep convection.Secondly,in LICOM-H,the stronger variability of AMOC is related to the higher sensitivity of the MLD and transformation to the prescribed atmospheric forcing in the Labrador Sea.展开更多
The Yellow Sea and Bohai Sea are among the global shelf seas susceptible to typhoons every year.Using observations and high-resolution numerical simulations,the current study investigates the dramatic changes in tempe...The Yellow Sea and Bohai Sea are among the global shelf seas susceptible to typhoons every year.Using observations and high-resolution numerical simulations,the current study investigates the dramatic changes in temperature and ocean heat content(OHC)of the Yellow Sea and Bohai Sea caused by Super Typhoon Maysak in early September 2020,which is representative of northward/northeastward-bypassing typhoons with centers just to the east of the study area.Temperature shows spatially coherent cooling in the upper mixed layer but warming in the subsurface layer in the majority of the offshore waters,due to wind-enhanced vertical mixing.In lower layers from the thermocline to sea bottom,temperature experiences significant warming in northeastern coastal waters of the Shandong Peninsula and in regions just off the Subei Shoal,but significant cooling in western coastal waters of the Korean Peninsula and southern coastal waters of the Shandong Peninsula.Significant temperature warming/cooling in lower layers is caused by coastal downwelling/upwelling.The total OHC of the study area decreases rapidly during Typhoon Maysak(2020)’s passage,which is generated comparably by latent heat loss at the sea surface and southward heat advection out of the study area at the southern boundary.Reduced shortwave radiation contributes positively but secondarily to the decreasing OHC during the first day.A numerical experiment suggests that Typhoon Maysak(2020)-induced OHC decline could have greatly affected the regional climate evolution in the following seasons.More studies are needed to fully understand the impacts of typhoons on regional climate changes in shelf seas at different time scales.展开更多
Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(EN...Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(ENSO)on summer precipitation in China.The inverse phase spatial distribution of sea surface temperature anomalies(SSTAs)in the southwest and northeast of the southern Indian Ocean is defined as the SIOD.Positive SIOD events(positive SSTAs in the southwest,negative SSTAs in the northeast)are associated with La Niña events(Central Pacific(CP)type),while negative SIOD events(negative SSTAs in the southwest,positive SSTAs in the northeast)are associated with El Niño events(Eastern Pacific(EP)type).Both SIOD and ENSO have certain impacts on summer precipitation in China.Precipitation in the Yangtze River basin decreases,while precipitation in southern China increases during pure positive SIOD(P_PSIOD)events.During pure negative SIOD(P_NSIOD)events,the changes in precipitation are exactly the opposite of those during P_PSIOD events,which may be due to differences in the cross-equatorial flow in the southern Indian Ocean,particularly in low-level Australian cross-equatorial flow.When positive SIOD and CP-type La Niña events occur simultaneously(PSIOD+La_Niña),precipitation increases in the Yangtze-Huaihe River basin,while it decreases in northern China.When negative SIOD and EP-type El Niño events occur simultaneously(NSIOD+El_Niño),precipitation in the Yangtze-Huaihe River basin is significantly lower than during P_NSIOD events.This is caused by differences in water vapor originating from the Pacific Ocean during different events.展开更多
As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operatio...As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.展开更多
This research evaluates the performance of an eddy-resolving forecast system(LFS)in simulating mesoscale eddies over the South China Sea(SCs)through a comparative analysis with satellite observations and the reanalysi...This research evaluates the performance of an eddy-resolving forecast system(LFS)in simulating mesoscale eddies over the South China Sea(SCs)through a comparative analysis with satellite observations and the reanalysis dataset from the Global Ocean Physics Reanalysis product(CMEMS).The findings indicate that the spatial characteristics of eddy kinetic energy,number,and amplitude of coherent mesoscale eddies simulated by LFS exhibit a reasonable agreement with satellite observations.The reproduced seasonal variations are also comparable to outputs from the CMEMS reanalysis dataset.Nevertheless,certain systematic biases have also been identified.In the SCS,LFS generates approximately 17%fewer eddies than observed.Such biases are also evident in the CMEMS reanalysis dataset.Similar to the statistics shown in the CMEMS reanalysis dataset,both cyclonic and anticyclonic eddies are significantly weaker in LFS compared to the observations.Additionally,the composite three-dimensional structures of mesoscale eddies simulated by LFS exhibit a remarkable similarity to those identified in the CMEMS reanalysis datasets.This work lays the foundation for further studies using LFS to investigate the predictability of mesoscale eddies and enhance the accuracy of simulations.展开更多
In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural a...In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.展开更多
Preferential policies,efficient government,and a favorable geographical location...a multitude of factors make the Hainan FTP a promising land for businesses.SOON after the Hainan Free Trade Port(FTP)launched special ...Preferential policies,efficient government,and a favorable geographical location...a multitude of factors make the Hainan FTP a promising land for businesses.SOON after the Hainan Free Trade Port(FTP)launched special customs operations at the end of 2025,private enterprises operating at its Yangpu Port began to benefit substantially from the favorable policies and surging growth momentum in the region.While riding on an ocean of opportunities opened by the FTP,local businesses are bringing the island to a new level of prosperity,and thriving together with it as a community of shared future.展开更多
Two predominant currents, the warm Kuroshio Current and the cold Oyashio Current, meet in the North- west Pacific Ocean. The dynamics of physical oceanographic structures in this region, including frontal zones and me...Two predominant currents, the warm Kuroshio Current and the cold Oyashio Current, meet in the North- west Pacific Ocean. The dynamics of physical oceanographic structures in this region, including frontal zones and meandering eddies, result in a highly productive habitat that serves as a favorable feeding ground for various commercially important species. Neon flying squid, Ommastrephes bartramii, is an im- portant oceanic squid, which is widely distributed in the North Pacific Ocean. Based on the catch data col- lected by Chinese squid jigging fleets and relevant environmental data, including sea surface temperature （SST） and fronts （represented by gradients of SST and thermocline） during 1998-2009, the variations of oceanic fronts and their influence on the fishing grounds of O. bartramii were evaluated, and the differ- ences in distribution of fishing grounds of O. bartramii in 2000 and 2002 were compared by describing the differences in vertical temperature between 0-300 m. It was found that the preferred horizontal tem- perature gradient of SST for O. bartramii tended to be centered at 0.01-0.02~C/nm, which attracted nearly 80% of the total fishing effort, and the preferred horizontal temperature gradients at the 50 m and 105 m layers were mainly located at 0.01-0.03~C/nm, which accounted for more than 70% of the total fishing effort during August-October. The preferred vertical temperature gradient within the 0-50 m layer for O. bartramii tended to be centered at 0.15-0.25~C/m during August and September and at 0.10-0.15~C/m in October, implying that the mixed surface layer was distributed at depths of 0-50 m. It was concluded that the vertical temperature gradient was more important than the horizontal temperature gradient in playing a role in forming the fishing ground. The results improved our understanding of the spatial dynamics of the 0. bartramii fishery.展开更多
Four sections of expendable conductivity-temperature-depth （XCTD） profiles from Fremantle, Australia to Antarctic Zhongshan Station and Moderate Resolution Imaging Spectroradiometer-Aquarius （MODIS-A） sea surface ...Four sections of expendable conductivity-temperature-depth （XCTD） profiles from Fremantle, Australia to Antarctic Zhongshan Station and Moderate Resolution Imaging Spectroradiometer-Aquarius （MODIS-A） sea surface temperature （SST） products were used to study the structure and seasonal variability of Southeast Indian Ocean fronts. Water mass analysis showed that surface water masses in the Southeast Indian Ocean were less salty in March than in November. Compared with November, the subtropical front （STF） moved southward about one degree of latitude in March, whereas seasonal variability of the subantarctic front （SAF） and polar front （PF） locations was not obvious. In March, the saline front moved northward about two degrees of latitude relative to the thermal front in the upper 100 m at the SAF, which was the northern boundary of sub- Antarctic surface water （SASW）. Analysis of climatological SST gradients from the satellite data showed that regions of enhanced sea surface temperature （SST） gradients were collocated with frontal locations identified with the XCTD data using water mass criteria. The surface expression of the PF identified by the SST gradient was further south by about one degree of latitude relative to the subsurface expression of the PF identified by the northern boundary of cold water.展开更多
Hydrographic data, ADCP velocity and sea level anomaly derived from the satellite altimeter have been jointly analyzed in the southeast lndian Ocean. Results show the locations and orientations of the major oceanic fr...Hydrographic data, ADCP velocity and sea level anomaly derived from the satellite altimeter have been jointly analyzed in the southeast lndian Ocean. Results show the locations and orientations of the major oceanic fronts as well as the characteristics of the currents within these fronts in the area. Double subtropical fronts are observed in the section along 120°E, which conflicts with the frontal structure frequently observed before the North Subtropical Front （NSTF） and South Subtropical Front （SSTF） merge into a single STF between 110°-115°E. The Subantarctic Front （SAF）, influenced by the out-of-phase double eddies, runs across 48°S three times between 120° and 127°E. The surface current within the SAF is strengthened up to 105.4 cm/s by the geostrophic effect of these eddies. Furthermore eddies may cause the strong current to split up into two branches within the SAF. The SAF and the primary polar front （PFI） can be identified individually in the ADCP data with a separation distance of about 0.3° at latitude between 140° and 145°E, although they cannot be identified separately in the low-resolution hydrographic data. The different thcrmohaline characteristics of Circumpolar Deep Water （CDW） and Modified Circumpolar Deep Water （MCDW） result in the formation of Southern Antarctic Circumpolar Current Front （SACCF） in the southeast Indian Ocean. It consistently turns northward along the east flank of the Kerguclen Plateau after it runs through the Princess Elizabeth Trough and turns southward sharply north of 60°S with a little seasonal variations. It is shown that the locations and orientations of the SAK the primary PF and SACCF in the ACC of the southeast Indian Ocean can be identified more precisely by the current distribution derived from ADCP data than by hydrographic data, because these fronts are usually accompanied by strong currents. However, the locations and orientations of the STF and the secondary PF are more difficult to be identified through current data, since these two fronts are usually not accompanied by any jet. The STF the and the secondary PF are usually confined in the first few hundred meters of the upper ocean and the latter is often determined by the northern terminus of 2 ℃ isothermal.展开更多
Altimeter and in situ data are used to estimate the mean surface zonal geostrophic current in the section along 115°E in the southern Indian Ocean,and the variation of strong currents in relation to the major fro...Altimeter and in situ data are used to estimate the mean surface zonal geostrophic current in the section along 115°E in the southern Indian Ocean,and the variation of strong currents in relation to the major fronts is studied.The results show that,in average,the flow in the core of Antarctic Circumpolar Current（ACC） along the section is composed of two parts,one corresponds to the jet of Subantarctic Front（SAF） and the other is the flow in the Polar Front Zone（PFZ）,with a westward flow between them.The mean surface zonal geostrophic current corresponding to the SAF is up to 49 cm · s^-1 at 46°S,which is the maximal velocity in the section.The eastward flow in the PFZ has a width of about 4.3 degrees in latitudes.The mean surface zonal geostrophic current corresponding to the Southern Antarctic Circumpolar Current Front（SACCF） is located at 59.7 °S with velocity less than 20 cm · s^-1.The location of zonal geostrophic jet corresponding to the SAF is quite stable during the study period.In contrast,the eastward jets in the PFZ exhibit various patterns,i.e.,the primary Polar Front（PF1） shows its strong meridional shift and the secondary Polar Front（PF2） does not always coincide with jet.The surface zonal geostrophic current corresponding to SAF has the significant periods of annual,semi-annual and four-month.The geostrophic current of the PFZ also shows significant periods of semi-annual and four-month,but is out of phase with the periods of the SAF,which results in no notable semi-annual and fourmonth periods in the surface zonal geostrophic current in the core of the ACC.In terms of annual cycle,the mean surface zonal geostrophic current in the core of the ACC shows its maximal velocity in June.展开更多
基金The research was partially funded by the Project 40571129 supported by the National Natural Science Foundation of ChinaInnovative Program(No.kzcx2-yw-304-1)supported by the Chinese Academy of Sciences.
文摘Analysis of ocean fronts＇ uncertainties indicates that they result from indiscemibility of their spatial position and fuzziness of their intensity. In view of this, a flow hierarchy for uncertainty representation of ocean fronts is proposed on the basis of fuzzy-rough set theory. Firstly, raster scanning and blurring are carried out on an ocean front, and the upper and lower approximate sets, the indiscernible relation in fuzzy-rough theories and related operators in fuzzy set theories are adopted to represent its uncertainties, then they are classified into three sets： with members one hundred percent belonging to the ocean front, belonging to the ocean front＇s edge and definitely not belonging to the ocean front. Finally, the approximate precision and roughness degree are utilized to evaluate the ocean front＇s degree of uncertainties and the precision of the representation. It has been proven that the method is not only capable of representing ocean fronts＇ uncertainties, but also provides a new theory and method for uncertainty representation of other oceanic phenomena.
基金supported by the National Natural Science Foundation of China (Grant Nos. 42406241,42325604,42227901)the Ministry of Science and Technology of China (No. 2021YFC2803304)+2 种基金the Program of Shanghai Academic/Technology Research Leader (22XD1403600)supported by the Swedish Research Council (Nos. 2020–03190 and 2024-04209)the Swedish Research Council for the Environment, Agricultural Sciences and Spatial Planning (No. 202400375)
文摘The oceanic mixed layer in the Southern Ocean is characterized by numerous fronts due to the stirring of freshwater influxes arising from ice melting.The interaction of these fronts with winds modulates the evolution of the mixed layer and affects atmosphere−ocean energy exchanges.However,the underlying mechanism behind the wind-front interaction remains obscure due to a lack of three-dimensional observations of the ocean,particularly in terms of velocities.To address this issue,this study investigates the dynamics of fronts within the mixed layer during a storm by employing a subset of the global submesoscale-permitting simulation,Northeast Weddell Sea Pre-SWOT Level-4 Hourly MITgcm LLC4320 Native Grid 2km Oceanographic Dataset(ROAM_MIZ).We first compare the ROAM_MIZ data to glider data to assess the performance of the model simulation and find that the ROAM_MIZ can,to a large degree,capture sub-mesoscale features within a mixed layer.Subsequent analyses based on a subset of ROAM_MIZ show that lateral density gradients within the mixed layer rapidly decrease during high winds associated with the storm.Down-front winds accelerate this process as the Ekman buoyancy transport responsible for enhancing the instability of the fronts is primarily dominated by horizontal baroclinic components.After the storm,the fronts strengthen again in the presence of weaker winds due to the frontogenesis by the larger-scale strain.Moreover,the non-geostrophic turbulence induces a modification of the relative vorticity,affecting the instability within the mixed layer.These findings offer valuable guidance for the deployment of observational instruments and subsequent analysis,as well as deepen the understanding of air−sea interactions in the Southern Ocean.
文摘On July 2^(nd),2025,32 scientists representing 15 countries gathered at Tartu,Estonia to make on-site endorsements for the Global ONCE(Ocean Negative Carbon Emissions)Program at the 12th INTECOL Wetlands Conference.This marks a significant milestone for ONCE in establishing a systematic framework for coastal wetland carbon sequestration research and global collaboration(Figs.1,2).Coastal wetlands are critical transition zones linking terrestrial and marine ecosystems,yet they face severe degradation from anthropogenic land-based activities and sea level rise that propagate impacts to the ocean.As a UN Ocean Decade Program,the Global ONCE Program champions interdisciplinary and cross-regional collaboration to enhance carbon sequestration in the ocean and coastal wetlands through science and innovation.Aligned with the Tartu Declaration on Wetlands that includes resolutions to promote the rights of global wetlands(especially peatlands)and advance the discipline of wetland science based on facts,this initiative addresses key knowledge gaps in land-ocean interactions.The goal is to harness the full potential of coastal wetlands and ocean systems for climate mitigation,thereby laying a scientific foundation for international policy formulation and implementation.
基金support from USA NSF(Grant No.OPP2213875)NASA(Grant No.80NSSC22K1707).
文摘The IUGG Associations for Atmosphere,Oceans and Cryosphere—IAMAS,IAPSO and IACS—held a Joint Scientific Assembly in Busan,South Korea,from 20 to 25 July 2025.This was the first joint assembly of all three associations since 2009,when they met in Montreal,Canada.It was the first time any of the associations had been hosted in Korea,and it had been two decades since any of them had met in Asia.The choice of Busan as the venue supported high levels of participation and smooth conference operations.The Local Organizing Committee,chaired by Prof.Kyung-Ja Ha of Pusan National University,oversaw the successful organization of the event.The assembly brought together 1725 participants in total,including 1282 researchers and 443 invited participants and individuals involved in side events,exhibitions,media coverage,and volunteer work.Participants came from 46 countries across Asia,Europe,North America,South America,Africa,and Oceania.IAMAS had 736 participants,IAPSO 321,and IACS 225.Survey data from 951 respondents revealed that Early Career Scientists,defined as those within 10 years of receiving their PhD,accounted for approximately 25%of participants.The demographic profile skewed young,with 66%of attendees in their 20s and 30s.The scientific program was organized by Prof.Seon-Ki Park(Chair),the Secretaries General from all three Associations,and the Local Organizing Committee.Reflecting the theme“Our Interconnected Earth,”the scientific program emphasized integrated approaches to climate systems,addressing climate change and environmental challenges through collaborative,transdisciplinary research.
基金supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(Grant nos.SML2021SP306,SML2023SP201)the National Key R&D Program of China(Grant no.2024YFF0506603)+1 种基金the National Natural Science Foundation of China(Grant no.42576020)Guangdong Basic and Applied Basic Research Foundation,China(Grant nos.2024A1515012717,2026A1515012241).
文摘Prydz Bay,East Antarctica,is a critical region for studying ocean–sea ice–ice shelf interactions and their role in the global climate system.This review synthesizes the advancements in numerical modeling of physical oceanographic processes in Prydz Bay,highlighting the evolution from early one-dimensional thermodynamic models to contemporary high-resolution,three-dimensional coupled ocean–sea ice–ice shelf frameworks.We discuss key milestones in understanding processes such as frazil ice dynamics and its impact on the basal mass balance of the Amery Ice Shelf,the pathways and mechanisms of Modified Circumpolar Deep Water intrusions,and the dynamic influences of large icebergs on regional circulation.Despite significant progress,challenges remain in integrating multi-component interactions and achieving long-term,high-resolution climate projections.Future efforts should focus on developing fully coupled models that incorporate atmosphere–ocean–sea ice–ice shelf–iceberg interactions,supported by enhanced observational networks and improved computational efficiency.This review underscores the importance of continued modeling advancement to better predict the responses of Antarctic ice shelves and polar climate to global change.
基金Supported by the Key Research and Development Program of Shandong(No.2022LZGC015)the National Key R&D Program of China(No.2022YFD2401400)+1 种基金the Taishan Scholars Program,the National Key R&D Program of China(No.2022YFD2400304)the Agricultural Seed Project of Shandong Key R&D Program(No.2024LZGCQY003)。
文摘Atmospheric carbon dioxide(CO_(2))levels are escalating at an unprecedented rate,leading to the phenomenon of ocean acidification(OA).Parental exposure to acidification has the potential to enhance offspring resilience through cross-generation plasticity.In this study,we analyzed larval growth and transcriptomic profiles in the Pacific oyster,Crassostrea gigas,a species of significant ecological relevance,under both control and elevated CO_(2)conditions experienced by their parental generation.Our findings indicate that the oyster populations exposed to OA exhibited a higher incidence of abnormalities during the D-shaped larval stage,followed by accelerated growth at the eyed stage.Through a comparative transcriptomic investigation of eyed larvae(25 d after fertilization),we observed that parental exposure to OA substantially influenced the gene expression in the offspring.Genes associated with lipid catabolism and shell formation were notably upregulated in oysters with parental OA exposure,potentially playing a role in cross-generational conditioning and conferring resilience to OA stressors.These results underscore the profound impact of OA on oyster larval development via cross-generational mechanisms and shed light on the molecular underpinnings of cross-generation plasticity.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.42430601,42175087)the Science and Technology Project of Gansu Province(Outstanding Youth Fund,Grant No.24JRRA386)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2024-jdzx04)。
文摘This study investigates the vertical variations of aerosol size distribution (0.06–1µm) and cloud condensation nuclei(CCN) spectra over the Southern Ocean (SO) using aircraft observations from the SOCRATES campaign.Results reveal a bimodal aerosol size distribution within the marine boundary layer (MBL),with peaks at diameters of~0.06µm and~0.65µm,dominated by sea-salt particles.Accumulation-mode aerosol concentrations decrease with altitude within the MBL,while Aitken-mode aerosol concentrations peak above the MBL (~2–3 km).Wind speed strongly correlates with coarse-mode aerosol concentration (R2=0.77),implicating sea spray as a major CCN source at low supersaturations (SS=0.1%).The altitudes of CCN concentration peaks shift from the MBL (<1 km,SS<0.4%) to the free troposphere (~2.5 km,SS>0.4%),suggesting new particle formation aloft,distinct from sea surface sources.These findings highlight the unique aerosol–CCN dynamics in the pristine SO,offering critical constraints for models simulating cloud–aerosol interactions in preindustrial-like environments.
基金supported by the National Natural Science Foundation of China [grant number 42176001]the State Key Laboratory of Tropical Oceanography,South China Sea Institute of Oceanology,Chinese Academy of Sciences [grant number LTO2106]the STU Scientific Research Foundation for Talents [grant number NTF21009]。
文摘The eddies in the southernmost southern Indian Ocean exert major dynamical and biogeochemical influences on the Earth system.Therefore,disentangling the relative contributions of vertical pumping and horizontal transport to water-property anomalies in the eddy cores is of fundamental importance.Here,the authors introduce a temperaturesalinity gradient-ratio approach(the"R-method")that compares vertical and meridional gradients to quantitatively separate the two processes.Application of the R-method to three-dimensional Argo observations reveals that horizontal transport,rather than vertical pumping,predominantly governs the observed temperature and salinity anomalies within eddy cores in the SIO.Independent theoretical estimations based on background meridional gradients,together with composites formed on isopycnal surfaces,further corroborate this conclusion.The results challenge the conventional assumption that vertical pumping invariably controls eddy-core property anomalies and demonstrate the utility of the R-method for diagnosing eddy impacts in climate and biogeochemical studies.
基金supported by the National Natural Science Foundation of China [grant number 92358302]。
文摘The present study compares the Atlantic Meridional Overturning Circulation(AMOC)in the North Atlantic from two simulations by an oceanic general circulation model with 1°×1°and 0.1°×0.1°resolution,respectively,which explores the sensitivity of AMOC to the resolution.The ocean model is the latest version of the LASG/IAP Climate System Model(LICOM3),and it is forced with atmospheric data from phase 2 of the Ocean Model Intercomparison Project(OMIP2).Comprehensive comparison between the two simulations indicates that the simulated AMOC is highly sensitive to the spatial resolution.The high-resolution model(LICOM-H)simulates a deeper mixed-layer depth(MLD),due to increased surface salinity,than that in the low-resolution model(LICOML)in the Labrador Sea,and it also has stronger AMOC strength(the maximum climatic mean AMOC from 1958 to 2018 is 23.4 Sv for LICOM-H and 21.2 Sv for LICOM-L)and larger variability of AMOC index(2.3 Sv for LICOM-H and 1.7 Sv for LICOM-L).These differences can mainly be attributed to two main dynamic processes that benefit from high resolution.Firstly,LICOM-H can simulate much stronger boundary currents(~0.6 m s^(-1))than LICOM-L(0.3 m s^(-1))in the upper ocean,which leads to saltier and warmer seawater being transported to the Labrador Sea,where it enhances deep convection.Secondly,in LICOM-H,the stronger variability of AMOC is related to the higher sensitivity of the MLD and transformation to the prescribed atmospheric forcing in the Labrador Sea.
基金supported by the National Key Research and Development Program of China(Grant Nos.2022YFF0801400 and 2021YFF0704002)the Shandong Provincial Natural Science Foundation(Grant No.ZR2024LQX002)the National Science Foundation of China(Grant No.42176016).
文摘The Yellow Sea and Bohai Sea are among the global shelf seas susceptible to typhoons every year.Using observations and high-resolution numerical simulations,the current study investigates the dramatic changes in temperature and ocean heat content(OHC)of the Yellow Sea and Bohai Sea caused by Super Typhoon Maysak in early September 2020,which is representative of northward/northeastward-bypassing typhoons with centers just to the east of the study area.Temperature shows spatially coherent cooling in the upper mixed layer but warming in the subsurface layer in the majority of the offshore waters,due to wind-enhanced vertical mixing.In lower layers from the thermocline to sea bottom,temperature experiences significant warming in northeastern coastal waters of the Shandong Peninsula and in regions just off the Subei Shoal,but significant cooling in western coastal waters of the Korean Peninsula and southern coastal waters of the Shandong Peninsula.Significant temperature warming/cooling in lower layers is caused by coastal downwelling/upwelling.The total OHC of the study area decreases rapidly during Typhoon Maysak(2020)’s passage,which is generated comparably by latent heat loss at the sea surface and southward heat advection out of the study area at the southern boundary.Reduced shortwave radiation contributes positively but secondarily to the decreasing OHC during the first day.A numerical experiment suggests that Typhoon Maysak(2020)-induced OHC decline could have greatly affected the regional climate evolution in the following seasons.More studies are needed to fully understand the impacts of typhoons on regional climate changes in shelf seas at different time scales.
基金supported by the National Natural Science Foundation of China[grant numbers 41975087,U2242212,and 41975085]supported by the National Natural Science Foundation of China[grant number U2242212]。
文摘Based on reanalysis data from 1979 to 2021,this study explores the spatial distribution of the Southern Indian Ocean Dipole(SIOD)and its individual and synergistic effects with the El Niño-Southern Oscillation(ENSO)on summer precipitation in China.The inverse phase spatial distribution of sea surface temperature anomalies(SSTAs)in the southwest and northeast of the southern Indian Ocean is defined as the SIOD.Positive SIOD events(positive SSTAs in the southwest,negative SSTAs in the northeast)are associated with La Niña events(Central Pacific(CP)type),while negative SIOD events(negative SSTAs in the southwest,positive SSTAs in the northeast)are associated with El Niño events(Eastern Pacific(EP)type).Both SIOD and ENSO have certain impacts on summer precipitation in China.Precipitation in the Yangtze River basin decreases,while precipitation in southern China increases during pure positive SIOD(P_PSIOD)events.During pure negative SIOD(P_NSIOD)events,the changes in precipitation are exactly the opposite of those during P_PSIOD events,which may be due to differences in the cross-equatorial flow in the southern Indian Ocean,particularly in low-level Australian cross-equatorial flow.When positive SIOD and CP-type La Niña events occur simultaneously(PSIOD+La_Niña),precipitation increases in the Yangtze-Huaihe River basin,while it decreases in northern China.When negative SIOD and EP-type El Niño events occur simultaneously(NSIOD+El_Niño),precipitation in the Yangtze-Huaihe River basin is significantly lower than during P_NSIOD events.This is caused by differences in water vapor originating from the Pacific Ocean during different events.
基金funded by Nansha District Science and Technology Project(Grant Number.2024ZD008)funded by China Geological Survey(Grant number:No.DD20230066,DD20242659).
文摘As a controllable power generation method requiring no energy storage,Ocean Thermal Energy Conversion(OTEC)technology demonstrates characteristics of abundant reserves,low pollution,and round-the-clock stable operation.The free-standing cold-water pipe(CWP)in the system withstands various complex loads during operation,posing potential failure risks.To reveal the deformation and stress mechanisms of OTEC CWPs,this study first analyzes wave particle velocity and acceleration to determine wave loads at different water depths.Based on the Euler-Bernoulli beam model,a quasi-static load calculation model for OTEC CWPs was established.The governing equations were discretized using the finite difference method,and matrix equations were solved to analyze bending deformation,bending moments,and surface stresses at discrete points along the pipe.Results indicate that water depths within 50 m represent a critical zone where wave particle velocity,acceleration,and wave loads exhibit significant variations in harmonic patterns,while beyond 50 m depth wave loads decrease linearly.Ocean currents and surface wind-driven currents substantially influence the CWP’s lateral displacement.Considering the effect of clump weights,the maximum lateral displacement occurs at 600–800 m below sea level.Utilizing large-wall-thickness high-strength pipes at the top section significantly enhances the structural safety of the CWP system.
基金supported by the National Key R&D Program for Developing Basic Sciences [grant number 2022YFC3104805]the National Natural Science Foundation of China [grant numbers 92358302 and 42306219]+1 种基金supported by the Tai Shan Scholar Program [grant number tstp20231237]Laoshan Laboratory project [grant number LSKJ202300301]。
文摘This research evaluates the performance of an eddy-resolving forecast system(LFS)in simulating mesoscale eddies over the South China Sea(SCs)through a comparative analysis with satellite observations and the reanalysis dataset from the Global Ocean Physics Reanalysis product(CMEMS).The findings indicate that the spatial characteristics of eddy kinetic energy,number,and amplitude of coherent mesoscale eddies simulated by LFS exhibit a reasonable agreement with satellite observations.The reproduced seasonal variations are also comparable to outputs from the CMEMS reanalysis dataset.Nevertheless,certain systematic biases have also been identified.In the SCS,LFS generates approximately 17%fewer eddies than observed.Such biases are also evident in the CMEMS reanalysis dataset.Similar to the statistics shown in the CMEMS reanalysis dataset,both cyclonic and anticyclonic eddies are significantly weaker in LFS compared to the observations.Additionally,the composite three-dimensional structures of mesoscale eddies simulated by LFS exhibit a remarkable similarity to those identified in the CMEMS reanalysis datasets.This work lays the foundation for further studies using LFS to investigate the predictability of mesoscale eddies and enhance the accuracy of simulations.
基金supported by the CAS Strategic Priority Research Program(No.XDB0760102),the Ministry of Science and Technology of China(No.2022YFF0802501)the Major Science and Technology Infrastructure Maintenance and Transformation Project of the Chinese Academy of Sciences,Shanghai Science and Technology Innovation Action Plan-Phospherus Project(No.23YF1426200)the National Key Research and Development Program of China(No.2024YFE0212200).
文摘In winter 2018,an aerosol physicochemical experiment was conducted in the Western Pacific Ocean(WPO)aboard the Research Vessel KEXUE of Chinese Academy of Sciences.This study systematically investigated both natural and anthropogenic effects on marine aerosols optical properties,as well as the applicability of multi-satellite products and IMPROVE equation.The averaged aerosol optical depth(AOD500 nm)was 0.31±0.16 andÅngström exponent440–675 nm was 0.29±0.30.In offshore China,significant anthropogenic emissions affected the marine environment.In remote WPO,dust aerosols transported from northern China,Siberia,Central Asia,and those settling from the upper troposphere originating from north Africa,Arabian peninsula,and western India,were dominant.The spatial trends of AOD were opposite in the mid-latitude and southern seas of WPO.The highest AOD,0.32±0.23,appeared along the coast of South Asia at mid-latitude,decreasing from offshore seas to remote oceans.In low-latitude and equatorial seas,AOD significantly increased from coast to remote oceans.Ångström exponent dropped significantly from the coast to remote oceans as anthropogenic influence diminished across the entire WPO.Correlation analysis showed that both MODIS-C6 and Himawari AOD prod-ucts showed similar applicability in coastal urban areas,while Himawari AOD is highly recommended for coastal background and marine environment due to its finer resolution.The extinction coefficient derived from PM_(2.5) chemical compositions using IMPROVE algorithm exhibited a significant correlation(R^(2)=0.58)with the con-currently measured AOD in the absence of long-distance transport,suggesting that the IMPROVE is a reasonable proxy of the columnar average of marine aerosol extinctions free from transport influences.
文摘Preferential policies,efficient government,and a favorable geographical location...a multitude of factors make the Hainan FTP a promising land for businesses.SOON after the Hainan Free Trade Port(FTP)launched special customs operations at the end of 2025,private enterprises operating at its Yangpu Port began to benefit substantially from the favorable policies and surging growth momentum in the region.While riding on an ocean of opportunities opened by the FTP,local businesses are bringing the island to a new level of prosperity,and thriving together with it as a community of shared future.
基金The National High-Tech R&D Program of China(863 Program)under contract Nos 2012AA092301 and 2012AA092303the Project of Shanghai Science and Technology Innovation under contract No.12231203900+1 种基金the Industrialization Program of National Development and Reform Commission under contract No.2159999the Shanghai Universities First-class Disciplines Project(Fisheries)"
文摘Two predominant currents, the warm Kuroshio Current and the cold Oyashio Current, meet in the North- west Pacific Ocean. The dynamics of physical oceanographic structures in this region, including frontal zones and meandering eddies, result in a highly productive habitat that serves as a favorable feeding ground for various commercially important species. Neon flying squid, Ommastrephes bartramii, is an im- portant oceanic squid, which is widely distributed in the North Pacific Ocean. Based on the catch data col- lected by Chinese squid jigging fleets and relevant environmental data, including sea surface temperature （SST） and fronts （represented by gradients of SST and thermocline） during 1998-2009, the variations of oceanic fronts and their influence on the fishing grounds of O. bartramii were evaluated, and the differ- ences in distribution of fishing grounds of O. bartramii in 2000 and 2002 were compared by describing the differences in vertical temperature between 0-300 m. It was found that the preferred horizontal tem- perature gradient of SST for O. bartramii tended to be centered at 0.01-0.02~C/nm, which attracted nearly 80% of the total fishing effort, and the preferred horizontal temperature gradients at the 50 m and 105 m layers were mainly located at 0.01-0.03~C/nm, which accounted for more than 70% of the total fishing effort during August-October. The preferred vertical temperature gradient within the 0-50 m layer for O. bartramii tended to be centered at 0.15-0.25~C/m during August and September and at 0.10-0.15~C/m in October, implying that the mixed surface layer was distributed at depths of 0-50 m. It was concluded that the vertical temperature gradient was more important than the horizontal temperature gradient in playing a role in forming the fishing ground. The results improved our understanding of the spatial dynamics of the 0. bartramii fishery.
基金supported by the Chinese Polar Environment Comprehensive Investigation & Assessment Programs (Grant nos. CHINARE2012-2016 for 01-01-07, CHINARE2016-01-01, and CHINARE2016-04-01)the National Natural Science Foundation of China (Grant nos. 41306206 and U1406404)
文摘Four sections of expendable conductivity-temperature-depth （XCTD） profiles from Fremantle, Australia to Antarctic Zhongshan Station and Moderate Resolution Imaging Spectroradiometer-Aquarius （MODIS-A） sea surface temperature （SST） products were used to study the structure and seasonal variability of Southeast Indian Ocean fronts. Water mass analysis showed that surface water masses in the Southeast Indian Ocean were less salty in March than in November. Compared with November, the subtropical front （STF） moved southward about one degree of latitude in March, whereas seasonal variability of the subantarctic front （SAF） and polar front （PF） locations was not obvious. In March, the saline front moved northward about two degrees of latitude relative to the thermal front in the upper 100 m at the SAF, which was the northern boundary of sub- Antarctic surface water （SASW）. Analysis of climatological SST gradients from the satellite data showed that regions of enhanced sea surface temperature （SST） gradients were collocated with frontal locations identified with the XCTD data using water mass criteria. The surface expression of the PF identified by the SST gradient was further south by about one degree of latitude relative to the subsurface expression of the PF identified by the northern boundary of cold water.
基金the National Natural Science Foundation of China undrer contract Nos 40376009, 40231013 ,49836010 the Ministry of Science and Technology of China under contract Nos 2003DIB4J135 , 2005DIB3J114the National Science Foundation of USA under contract No. 0PP0230284.
文摘Hydrographic data, ADCP velocity and sea level anomaly derived from the satellite altimeter have been jointly analyzed in the southeast lndian Ocean. Results show the locations and orientations of the major oceanic fronts as well as the characteristics of the currents within these fronts in the area. Double subtropical fronts are observed in the section along 120°E, which conflicts with the frontal structure frequently observed before the North Subtropical Front （NSTF） and South Subtropical Front （SSTF） merge into a single STF between 110°-115°E. The Subantarctic Front （SAF）, influenced by the out-of-phase double eddies, runs across 48°S three times between 120° and 127°E. The surface current within the SAF is strengthened up to 105.4 cm/s by the geostrophic effect of these eddies. Furthermore eddies may cause the strong current to split up into two branches within the SAF. The SAF and the primary polar front （PFI） can be identified individually in the ADCP data with a separation distance of about 0.3° at latitude between 140° and 145°E, although they cannot be identified separately in the low-resolution hydrographic data. The different thcrmohaline characteristics of Circumpolar Deep Water （CDW） and Modified Circumpolar Deep Water （MCDW） result in the formation of Southern Antarctic Circumpolar Current Front （SACCF） in the southeast Indian Ocean. It consistently turns northward along the east flank of the Kerguclen Plateau after it runs through the Princess Elizabeth Trough and turns southward sharply north of 60°S with a little seasonal variations. It is shown that the locations and orientations of the SAK the primary PF and SACCF in the ACC of the southeast Indian Ocean can be identified more precisely by the current distribution derived from ADCP data than by hydrographic data, because these fronts are usually accompanied by strong currents. However, the locations and orientations of the STF and the secondary PF are more difficult to be identified through current data, since these two fronts are usually not accompanied by any jet. The STF the and the secondary PF are usually confined in the first few hundred meters of the upper ocean and the latter is often determined by the northern terminus of 2 ℃ isothermal.
基金The Ministry of Science and Technology,China grant Nos. 2006BAB18B02 and 2008DFA20420the National Natural Science Foundation of China grant No. 40376009
文摘Altimeter and in situ data are used to estimate the mean surface zonal geostrophic current in the section along 115°E in the southern Indian Ocean,and the variation of strong currents in relation to the major fronts is studied.The results show that,in average,the flow in the core of Antarctic Circumpolar Current（ACC） along the section is composed of two parts,one corresponds to the jet of Subantarctic Front（SAF） and the other is the flow in the Polar Front Zone（PFZ）,with a westward flow between them.The mean surface zonal geostrophic current corresponding to the SAF is up to 49 cm · s^-1 at 46°S,which is the maximal velocity in the section.The eastward flow in the PFZ has a width of about 4.3 degrees in latitudes.The mean surface zonal geostrophic current corresponding to the Southern Antarctic Circumpolar Current Front（SACCF） is located at 59.7 °S with velocity less than 20 cm · s^-1.The location of zonal geostrophic jet corresponding to the SAF is quite stable during the study period.In contrast,the eastward jets in the PFZ exhibit various patterns,i.e.,the primary Polar Front（PF1） shows its strong meridional shift and the secondary Polar Front（PF2） does not always coincide with jet.The surface zonal geostrophic current corresponding to SAF has the significant periods of annual,semi-annual and four-month.The geostrophic current of the PFZ also shows significant periods of semi-annual and four-month,but is out of phase with the periods of the SAF,which results in no notable semi-annual and fourmonth periods in the surface zonal geostrophic current in the core of the ACC.In terms of annual cycle,the mean surface zonal geostrophic current in the core of the ACC shows its maximal velocity in June.
