Both vertical and horizontal profiles of total dissolved selenium,dissolved organic and inorganic selenium,including Se(IV)and Se(VI),as well as particulate selenium in seawater were obtained on a basis of newly devel...Both vertical and horizontal profiles of total dissolved selenium,dissolved organic and inorganic selenium,including Se(IV)and Se(VI),as well as particulate selenium in seawater were obtained on a basis of newly developed separation technique form Antarctic Ocean,where the prodiction of deep waters occurs.The results exhibited that the concentrations of Se(IV) and Se(VI) were elevated and the total concentration in the surface of the high latitude waters (1. 31 nmol/L) was above those at lower latitudes (1.09 nmol/L) and also that previously reported from the Southern Ocean(1.18 nmol/L,Suzuki,1987).Preliminary investigation using specifically designed microlayer-sampler,that was first employed to identify the main biogeochemical proeesses,revealed Antarctic Ocean being functioning as a potential source as selenium in sea-air exchange. The mean life time of the selenium,detected as Se(IV) in deep water, was also estimated rather shorter than the residence time of the water mass, based on the samples collected from the cruise of China's Sixth Scientific Expedition.展开更多
Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water-soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used ...Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water-soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used to recover water-soluble proteins while leaving the fluoride in solution. After freezing and thawing the wash water, protein and fluoride contents of the thawed fractions were determined to explore the melting regularity of components in the wash water. The highest concentration factors of protein and fluoride were obtained after 80 min of thawing, such as 1.48 ± 0.06 and 1.35 ± 0.04 times, respectively. The free amino-nitrogen(FAN) content and sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern results revealed that the highest concentrations of all ingredients were obtained after 80 min of the process. The degree of hydrolysis of all fractions from the thawing process fluctuated in a narrow range around 12% during the entire process, indicating that the thawing order did not change with various proteins or time during the entire thawing course. These results demonstrate that the freeze concentration method can be used to concentrate protein solutions, even those with fluoride. It was concluded that condensation was achieved and no ingredient could be separated, regardless of fluoride, amino acids, or different proteins in the water.展开更多
Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter da...Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series,as other radar altimetry satellites can,needs further investigation.This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data.We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature(IST)product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images.Second,a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights.We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation.Finally,the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate(ASPeCt)ship-based observed sea ice thickness.The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable,and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m.The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products;this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.展开更多
Polynyas are irregular open water bodies within the sea ice cover in polar regions under freezing weather conditions.In this study,we reviewed the progress of research work on dynamical forcing,sea ice production(SIP)...Polynyas are irregular open water bodies within the sea ice cover in polar regions under freezing weather conditions.In this study,we reviewed the progress of research work on dynamical forcing,sea ice production(SIP),and water mass formation for both coastal polynyas and open-ocean polynyas in the Southern Ocean,as well as the variability and controlling mechanisms of polynya processes on different time scales.Polynyas play an irreplaceable role in the regulation of global ocean circulation and biological processes in regional ocean ecosystems.The coastal polynyas(latent heat polynyas)are mainly located in the Weddell Sea,the Ross Sea and on the west side of protruding topographic features in East Antarctica.During the formation of coastal polynyas,which are mainly forced by offshore winds or ocean currents,brine rejection triggered by high SIP results in the formation of high salinity shelf water,which is the predecessor of the Antarctic bottom water-the lower limb of the global thermohaline circulation.The open-ocean polynyas(sensible heat polynyas)are mainly found in the Indian sector of the Southern Ocean,which are formed by ocean convection processes generated by topography and negative wind stress curl.The convection processes bring nutrients into the upper ocean,which supports biological production and makes the polynya regions an important sink for atmospheric carbon dioxide.The limitations and challenges in polynya research are also discussed.展开更多
The Argo float observations are used to investigate the mesoscale characteristics of the Antarctic Intermediate Water (AAIW) in the South Pacific in this paper. It is shown that a subsurface mesoscale phenomenon is ...The Argo float observations are used to investigate the mesoscale characteristics of the Antarctic Intermediate Water (AAIW) in the South Pacific in this paper. It is shown that a subsurface mesoscale phenomenon is probably touched by an Argo float during the float's ascent-descent cycles and is identified by the horizontal salinity gradient between the vertical temperature-salinity profiles. This shows that the transportation of the AAIW may be accompanied with the rich mesoscale characteristics. To derive the spatial length, time, and propagation characteristics of the mesoscale variability of the AAIW, the gridded temperature-salinity dataset ENACT/ENSEMBLE Version 3 constructed on the in-situ observations in the South Pacific since 2005 is used. The Empirical Mode Decomposition method is applied to decompose the isopycnal-averaged salinity anomaly from 26.8 cr0-27.4 ao, where the AAIW mainly resides, into the basin scale and two mesoscale modes. It is found that the first mesoscale mode with the length scale on the order of 1 000 km explains nearly 50% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speeds are slower in the mid-latitude (around 1 cm/s) and faster in the low latitude (around 6 cm/s), but with an increasing in the latitude band on 25^-30~S. The second mesoscale mode is of the length scale on the order of 500 km, explaining about 30% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speed keeps nearly unchanged (around 0.5 cm/s). These results presented the stronger turbulent motion of the subsurface ocean on the spatial scale, and also described the significant role of Argo program for the better understanding of the deep ocean.展开更多
Antarctic Bottom Water(AABW)plays an important role in the meridional overturning circulation and contributes significantly to global heat transport and sea level rise(SLR).Based on the Global Ocean(1/12)°Physica...Antarctic Bottom Water(AABW)plays an important role in the meridional overturning circulation and contributes significantly to global heat transport and sea level rise(SLR).Based on the Global Ocean(1/12)°Physical Reanalysis(GLORYS12V1)products and conductivity-temperature-depth instrument data from the World Ocean Circulation Experiment hydrographic program,we analyzed the trends in the thickness,volume,temperature,salinity,and neutral density of the AABW in the Amundsen Sea from 1993 to 2017.Over the past 25 years,the volume has decreased by 3.45×10^(12) m^(3)/a,thinning at a rate of 5 m/a.In the vertical direction,the contraction of the AABW is compensated by the volume expansion of the Circumpolar Deep Water.As the volume of AABW decreases,the temperature of the AABW increases by about 0.002℃/a.This warming is equivalent to a heat flux of 0.27 W/m^(2).A local SLR is produced due to thermal expansion of 0.35 mm/a.During the study period,the neutral density decreased by 0.0003 kg/(m^(3)·a)due to warming.In the horizontal direction,the volume of AABW flowing from the Ross Sea into the Amundsen Sea gradually decreases and the temperature of the AABW increases continuously.The horizontal transport loss of the AABW volume is 4.07×10^(14) m^(3) and the horizontal heat transport results in a 0.03℃ increase in the temperature of the AABW.展开更多
The some trace elements in the Antarctic and Arctic snow, ice, water were studied using the methodology and theory of water vapor chemistry. The concentrations of ions Zn 2+ , Cd 2+ , Pb 2+ , Cu 2+ , S...The some trace elements in the Antarctic and Arctic snow, ice, water were studied using the methodology and theory of water vapor chemistry. The concentrations of ions Zn 2+ , Cd 2+ , Pb 2+ , Cu 2+ , Sn 4+ , Bi 3+ in Antarctic and Arctic snow a significant spatial similarity; they are also close to those defined elsewhere on the basic of studies of water vapor chemistry: on average Zn 2+ 5.0 μg/L, Cd 2+ 0.080 μg/L, Pb 2+ 0.030 μg/L, Cu 2+ 0.70 μg/L, Sn 4+ 0.99 μg/L, Bi 3+ 0.18 μg/L. Apparently, the ion concentration in the Antarctic and Arctic region represent natural baseline values and are controlled by natural water cycles.展开更多
On the basis of the salinity distribution of isopycnal(σ_0=27.2 kg/m^3) surface and in salinity minimum, the Antarctic Intermediate Water(AAIW) around South Australia can be classified into five types correspondi...On the basis of the salinity distribution of isopycnal(σ_0=27.2 kg/m^3) surface and in salinity minimum, the Antarctic Intermediate Water(AAIW) around South Australia can be classified into five types corresponding to five regions by using in situ CTD observations. Type 1 is the Tasman AAIW, which has consistent hydrographic properties in the South Coral Sea and the North Tasman Sea. Type 2 is the Southern Ocean(SO) AAIW, parallel to and extending from the Subantarctic Front with the freshest and coldest AAIW in the study area. Type 3 is a transition between Type 1 and Type 2. The AAIW transforms from fresh to saline with the latitude declining(equatorward). Type 4, the South Australia AAIW, has relatively uniform AAIW properties due to the semienclosed South Australia Basin. Type 5, the Southeast Indian AAIW, progressively becomes more saline through mixing with the subtropical Indian intermediate water from south to north. In addition to the above hydrographic analysis of AAIW, the newest trajectories of Argo(Array for real-time Geostrophic Oceanography) floats were used to constructed the intermediate(1 000 m water depth) current field, which show the major interocean circulation of AAIW in the study area. Finally, a refined schematic of intermediate circulation shows that several currents get together to complete the connection between the Pacific Ocean and the Indian Ocean. They include the South Equatorial Current and the East Australia Current in the Southwest Pacific Ocean, the Tasman Leakage and the Flinders Current in the South Australia Basin, and the extension of Flinders Current in the southeast Indian Ocean.展开更多
Dissolved nutrients are essential to marine productivity and ecosystem structures in the Southern Ocean.The spatial distributions of dissolved nutrients in the Cosmonaut Sea were studied during the 37th Chinese Nation...Dissolved nutrients are essential to marine productivity and ecosystem structures in the Southern Ocean.The spatial distributions of dissolved nutrients in the Cosmonaut Sea were studied during the 37th Chinese National Antarctic Research Expedition in 2021.The relative standard deviations of the nitrate(NO_(3)-N),nitrite(NO_(2)-N),ammonium(NH_(4)-N),phosphate(PO_(4)-P),and silicate(SiO_(3)-Si)concentrations found in duplicate samples(n=2)were 1.01%,9.04%,6.45%,0.94%,and0.67%,respectively.The mean NO_(3)-N,NO_(2)-N,NH_(4)-N,PO_(4)-P,and SiO_(3)-Si concentrations in the mixed layer were 26.41±4.13,0.15±0.09,0.51±0.22,1.73±0.23,and 41.48±6.94μmol·L^(−1),respectively,and were higher than the relevant limitationconcentrations.The concentrations were generally bounded horizontally by the Southern Boundary(SB)of the Antarctic Circumpolar Current,the NO_(3)-N,NO_(2)-N,NH_(4)-N,and PO_(4)-P concentrations being higher northeast than southwest of the SB but the SiO_(3)-Si concentrations being higher southwest than northeast,indicating that the SB dominates nutrient distributions in themixed layer.The NO_(3)-N,NH_(4)-N,and PO_(4)-P concentrations gradually increased moving vertically down from the mixed layer to 200 m deep and then remained at 33.73±3.51,0.26±0.13,and 2.28±0.10μmol·L^(−1),respectively,to the bottom.The SiO_(3)-Si concentration increased as depth increased and reached a maximum in the bottom layer.The NO_(2)-N concentrationdecreased rapidly as depth increased and was~0μmol·L^(−1)at>150 m deep.Circumpolar Deep Water upwelling may cause high nutrient concentrations in shallower layers up to the 100 m layer between 62.5°S and 64°S.展开更多
With high-resolution conductivity-temperature-depth (CTD) observations conducted in Oct.-Nov. 2005, this study provides a detailed quasi-synoptic description of the North Pacific Tropic Water (NPTW), North Pacific...With high-resolution conductivity-temperature-depth (CTD) observations conducted in Oct.-Nov. 2005, this study provides a detailed quasi-synoptic description of the North Pacific Tropic Water (NPTW), North Pacific Intermediate Water (NPIW) and Antarctic Intermediate Water (AAIW) in the western North Pacific. Some novel features are found. NPTW enters the western ocean with highest-salinity core off shore at 15°-18°N, and then splits to flow northward and southward along the western boundary. Its salinity decreases and density increases outside the core region. NPIW spreads westward north of 15°N with lowest salinity off shore at 21°N, but mainly hugs the Mindanao coast south of 12°N. It shoals and thins toward the south, with salinity increasing and density decreasing. AAIW extends to higher latitude off shore than that in shore, and it is traced as a salinity minimum to only 10°N at 130°E. Most of the South Pacific waters turn northeastward rather than directly flow northward upon reaching to the Mindanao coast, indicating the eastward shift of the Mindanao Undercurrent (MUC).展开更多
The dimensional and temporal distribution of Antarctic Intermediate Water(AAIW)and North Pacifi c Intermediate Water(NPIW)in the Philippine Sea were explored using Argo profi les and gridded Argo data.As the salinity ...The dimensional and temporal distribution of Antarctic Intermediate Water(AAIW)and North Pacifi c Intermediate Water(NPIW)in the Philippine Sea were explored using Argo profi les and gridded Argo data.As the salinity minimum of intermediate water from mid-high latitude of the southern and northern hemisphere of the Pacifi c Ocean,the properties of AAIW and NPIW merge at about 10°N with diff erent properties in the Philippine Sea.The core of AAIW is located below 600 dbar with potential density of 27≤σθ≤27.3 kg/m 3 and salinity of 34.5≤S≤34.55.The core of NPIW is located between 300–700 dbar with potential density of 26.2≤σθ≤27 kg/m 3 and salinity of 34≤S≤34.4.The volume of AAIW and NPIW during January 2004 to December 2017 is negatively correlated.The time series of AAIW and NPIW is dominated by signifi cant periods of 6 and 8 months,respectively.The variations of AAIW and NPIW are mainly aff ected by volume transport through a 130°E section by the North Equatorial Current(NEC)and North Equatorial Undercurrent(NEUC).展开更多
Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's ...Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's life forms.Despite various approaches to access and directly sample subglacial water and sediments,clean access and exploration of subglacial lakes remain challenging.To address this concern,Jilin University has developed the RECoverable Autonomous Sonde(RECAS)prototype.This technology enables sampling and in-situ detection of subglacial lake water while being isolated from the surface,thus minimizing the risk of pollution.Laboratory tests,including downward and upward drilling,long-running,remote-control,and cold-environment assessments,were conducted to validate the sonde's principle and functionality.During the 38th Chinese National Antarctic Research Expedition,CHINARE(2021–2022 season),the RECAS prototype underwent testing on the flank region of Dalk glacier,10 km from Zhongshan Station in Antarctica.Three boreholes with depths of 200.3,183.2,and 133.5 m were successfully drilled,with the refrozen meltwater sealing the boreholes during the process.Approximately 600 mL of melted water samples were collected from each hole.Throughout the drilling tests,all systems of the RECAS prototype performed within the expected ranges.展开更多
A streamfunction EOF method is applied to a time series of hydrographic sections in the Southern Ocean south of Australia to study water mass variations. Results show that there are large thermohaline variations north...A streamfunction EOF method is applied to a time series of hydrographic sections in the Southern Ocean south of Australia to study water mass variations. Results show that there are large thermohaline variations north of the Subantarctic Front (SAF) at 300–1500 dbar level, indicating upwelling and downwelling of the Antarctic Intermediate Water (AAIW) along isopycnal surfaces. Based on the latest altimeter product, Absolute Dynamic Topography, a mechanism due to frontal wave propagation is proposed to explain this phenomenon, and an index for frontal waves is defined. When the frontal wave is in positive (negative) phase, the SAF flows northeastward (southeastward) with the fresh AAIW downwelling (upwelling). Such mesoscale processes greatly enhance cross-frontal exchanges of water masses. Spectral analysis shows that frontal waves in the Southern Ocean south of Australia are dominated by a period of about 130 days with a phase speed of 4 cm/s and a wavelength of 450 km.展开更多
文摘Both vertical and horizontal profiles of total dissolved selenium,dissolved organic and inorganic selenium,including Se(IV)and Se(VI),as well as particulate selenium in seawater were obtained on a basis of newly developed separation technique form Antarctic Ocean,where the prodiction of deep waters occurs.The results exhibited that the concentrations of Se(IV) and Se(VI) were elevated and the total concentration in the surface of the high latitude waters (1. 31 nmol/L) was above those at lower latitudes (1.09 nmol/L) and also that previously reported from the Southern Ocean(1.18 nmol/L,Suzuki,1987).Preliminary investigation using specifically designed microlayer-sampler,that was first employed to identify the main biogeochemical proeesses,revealed Antarctic Ocean being functioning as a potential source as selenium in sea-air exchange. The mean life time of the selenium,detected as Se(IV) in deep water, was also estimated rather shorter than the residence time of the water mass, based on the samples collected from the cruise of China's Sixth Scientific Expedition.
基金supported by the Key Research and Development Project of Shandong Province (No.2015 GSF115005)the Huimin Special Fund of Qingdao Municipal Achievement Transformation Plan (No.15-9-2-120NSH)the National Natural Science Foundation of China (No.31101380)
文摘Water-washing removes fluoride from Antarctic krill but produces large volumes of wash water containing water-soluble proteins and fluoride. The freeze concentration method was tested to determine if it could be used to recover water-soluble proteins while leaving the fluoride in solution. After freezing and thawing the wash water, protein and fluoride contents of the thawed fractions were determined to explore the melting regularity of components in the wash water. The highest concentration factors of protein and fluoride were obtained after 80 min of thawing, such as 1.48 ± 0.06 and 1.35 ± 0.04 times, respectively. The free amino-nitrogen(FAN) content and sodium dodecyl sulfate-polyacrylamide gel electrophoresis pattern results revealed that the highest concentrations of all ingredients were obtained after 80 min of the process. The degree of hydrolysis of all fractions from the thawing process fluctuated in a narrow range around 12% during the entire process, indicating that the thawing order did not change with various proteins or time during the entire thawing course. These results demonstrate that the freeze concentration method can be used to concentrate protein solutions, even those with fluoride. It was concluded that condensation was achieved and no ingredient could be separated, regardless of fluoride, amino acids, or different proteins in the water.
基金The National Natural Science Foundation of China under contract No.42076235.
文摘Antarctic sea ice is an important part of the Earth’s atmospheric system,and satellite remote sensing is an important technology for observing Antarctic sea ice.Whether Chinese Haiyang-2B(HY-2B)satellite altimeter data could be used to estimate sea ice freeboard and provide alternative Antarctic sea ice thickness information with a high precision and long time series,as other radar altimetry satellites can,needs further investigation.This paper proposed an algorithm to discriminate leads and then retrieve sea ice freeboard and thickness from HY-2B radar altimeter data.We first collected the Moderate-resolution Imaging Spectroradiometer ice surface temperature(IST)product from the National Aeronautics and Space Administration to extract leads from the Antarctic waters and verified their accuracy through Sentinel-1 Synthetic Aperture Radar images.Second,a surface classification decision tree was generated for HY-2B satellite altimeter measurements of the Antarctic waters to extract leads and calculate local sea surface heights.We then estimated the Antarctic sea ice freeboard and thickness based on local sea surface heights and the static equilibrium equation.Finally,the retrieved HY-2B Antarctic sea ice thickness was compared with the CryoSat-2 sea ice thickness and the Antarctic Sea Ice Processes and Climate(ASPeCt)ship-based observed sea ice thickness.The results indicate that our classification decision tree constructed for HY-2B satellite altimeter measurements was reasonable,and the root mean square error of the obtained sea ice thickness compared to the ship measurements was 0.62 m.The proposed sea ice thickness algorithm for the HY-2B radar satellite fills a gap in this application domain for the HY-series satellites and can be a complement to existing Antarctic sea ice thickness products;this algorithm could provide long-time-series and large-scale sea ice thickness data that contribute to research on global climate change.
基金This work is funded by the National Natural Science Foundation of China(Grant nos.41941008 and 41876221)the Shanghai Science and Technology Committee(Grant nos.20230711100 and 21QA1404300)+2 种基金the Academy of Finland(Grant no.304345)the Ministry of Natural Resources of the People’s Republic of China(Impact and Response of Antarctic Seas to Climate Change,Grant no.IRASCC 1-02-01B)the Advanced Polar Science Institute of Shanghai(APSIS).
文摘Polynyas are irregular open water bodies within the sea ice cover in polar regions under freezing weather conditions.In this study,we reviewed the progress of research work on dynamical forcing,sea ice production(SIP),and water mass formation for both coastal polynyas and open-ocean polynyas in the Southern Ocean,as well as the variability and controlling mechanisms of polynya processes on different time scales.Polynyas play an irreplaceable role in the regulation of global ocean circulation and biological processes in regional ocean ecosystems.The coastal polynyas(latent heat polynyas)are mainly located in the Weddell Sea,the Ross Sea and on the west side of protruding topographic features in East Antarctica.During the formation of coastal polynyas,which are mainly forced by offshore winds or ocean currents,brine rejection triggered by high SIP results in the formation of high salinity shelf water,which is the predecessor of the Antarctic bottom water-the lower limb of the global thermohaline circulation.The open-ocean polynyas(sensible heat polynyas)are mainly found in the Indian sector of the Southern Ocean,which are formed by ocean convection processes generated by topography and negative wind stress curl.The convection processes bring nutrients into the upper ocean,which supports biological production and makes the polynya regions an important sink for atmospheric carbon dioxide.The limitations and challenges in polynya research are also discussed.
基金The National Natural Science Foundation of China under contract No.41176029the Basic Scientific Fund for National Public Research Institute of China under contract No.GY02-2012G25
文摘The Argo float observations are used to investigate the mesoscale characteristics of the Antarctic Intermediate Water (AAIW) in the South Pacific in this paper. It is shown that a subsurface mesoscale phenomenon is probably touched by an Argo float during the float's ascent-descent cycles and is identified by the horizontal salinity gradient between the vertical temperature-salinity profiles. This shows that the transportation of the AAIW may be accompanied with the rich mesoscale characteristics. To derive the spatial length, time, and propagation characteristics of the mesoscale variability of the AAIW, the gridded temperature-salinity dataset ENACT/ENSEMBLE Version 3 constructed on the in-situ observations in the South Pacific since 2005 is used. The Empirical Mode Decomposition method is applied to decompose the isopycnal-averaged salinity anomaly from 26.8 cr0-27.4 ao, where the AAIW mainly resides, into the basin scale and two mesoscale modes. It is found that the first mesoscale mode with the length scale on the order of 1 000 km explains nearly 50% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speeds are slower in the mid-latitude (around 1 cm/s) and faster in the low latitude (around 6 cm/s), but with an increasing in the latitude band on 25^-30~S. The second mesoscale mode is of the length scale on the order of 500 km, explaining about 30% variability of the mesoscale characteristics of the AAIW. Its westward-propagation speed keeps nearly unchanged (around 0.5 cm/s). These results presented the stronger turbulent motion of the subsurface ocean on the spatial scale, and also described the significant role of Argo program for the better understanding of the deep ocean.
基金The Impact and Response of Antarctic Seas to Climate Change Program under contract No.RFSOCC2020-2022-No.18the National Key Research and Development Program of China under contract No.2016YFA0601301。
文摘Antarctic Bottom Water(AABW)plays an important role in the meridional overturning circulation and contributes significantly to global heat transport and sea level rise(SLR).Based on the Global Ocean(1/12)°Physical Reanalysis(GLORYS12V1)products and conductivity-temperature-depth instrument data from the World Ocean Circulation Experiment hydrographic program,we analyzed the trends in the thickness,volume,temperature,salinity,and neutral density of the AABW in the Amundsen Sea from 1993 to 2017.Over the past 25 years,the volume has decreased by 3.45×10^(12) m^(3)/a,thinning at a rate of 5 m/a.In the vertical direction,the contraction of the AABW is compensated by the volume expansion of the Circumpolar Deep Water.As the volume of AABW decreases,the temperature of the AABW increases by about 0.002℃/a.This warming is equivalent to a heat flux of 0.27 W/m^(2).A local SLR is produced due to thermal expansion of 0.35 mm/a.During the study period,the neutral density decreased by 0.0003 kg/(m^(3)·a)due to warming.In the horizontal direction,the volume of AABW flowing from the Ross Sea into the Amundsen Sea gradually decreases and the temperature of the AABW increases continuously.The horizontal transport loss of the AABW volume is 4.07×10^(14) m^(3) and the horizontal heat transport results in a 0.03℃ increase in the temperature of the AABW.
文摘The some trace elements in the Antarctic and Arctic snow, ice, water were studied using the methodology and theory of water vapor chemistry. The concentrations of ions Zn 2+ , Cd 2+ , Pb 2+ , Cu 2+ , Sn 4+ , Bi 3+ in Antarctic and Arctic snow a significant spatial similarity; they are also close to those defined elsewhere on the basic of studies of water vapor chemistry: on average Zn 2+ 5.0 μg/L, Cd 2+ 0.080 μg/L, Pb 2+ 0.030 μg/L, Cu 2+ 0.70 μg/L, Sn 4+ 0.99 μg/L, Bi 3+ 0.18 μg/L. Apparently, the ion concentration in the Antarctic and Arctic region represent natural baseline values and are controlled by natural water cycles.
基金The Chinese Polar Environment Comprehensive Investigation and Assessment Programs under contract Nos CHINARE-04-04 and CHINARE-04-01
文摘On the basis of the salinity distribution of isopycnal(σ_0=27.2 kg/m^3) surface and in salinity minimum, the Antarctic Intermediate Water(AAIW) around South Australia can be classified into five types corresponding to five regions by using in situ CTD observations. Type 1 is the Tasman AAIW, which has consistent hydrographic properties in the South Coral Sea and the North Tasman Sea. Type 2 is the Southern Ocean(SO) AAIW, parallel to and extending from the Subantarctic Front with the freshest and coldest AAIW in the study area. Type 3 is a transition between Type 1 and Type 2. The AAIW transforms from fresh to saline with the latitude declining(equatorward). Type 4, the South Australia AAIW, has relatively uniform AAIW properties due to the semienclosed South Australia Basin. Type 5, the Southeast Indian AAIW, progressively becomes more saline through mixing with the subtropical Indian intermediate water from south to north. In addition to the above hydrographic analysis of AAIW, the newest trajectories of Argo(Array for real-time Geostrophic Oceanography) floats were used to constructed the intermediate(1 000 m water depth) current field, which show the major interocean circulation of AAIW in the study area. Finally, a refined schematic of intermediate circulation shows that several currents get together to complete the connection between the Pacific Ocean and the Indian Ocean. They include the South Equatorial Current and the East Australia Current in the Southwest Pacific Ocean, the Tasman Leakage and the Flinders Current in the South Australia Basin, and the extension of Flinders Current in the southeast Indian Ocean.
基金financially supported by National Polar Special Program “Impact and Response of Antarctic Seas to Climate Change” (Grant nos. IRASCC 01-01-02A, IRASCC 02-02)the National Natural Science Foundation of China (NSFC) (Grant no. 41976228)
文摘Dissolved nutrients are essential to marine productivity and ecosystem structures in the Southern Ocean.The spatial distributions of dissolved nutrients in the Cosmonaut Sea were studied during the 37th Chinese National Antarctic Research Expedition in 2021.The relative standard deviations of the nitrate(NO_(3)-N),nitrite(NO_(2)-N),ammonium(NH_(4)-N),phosphate(PO_(4)-P),and silicate(SiO_(3)-Si)concentrations found in duplicate samples(n=2)were 1.01%,9.04%,6.45%,0.94%,and0.67%,respectively.The mean NO_(3)-N,NO_(2)-N,NH_(4)-N,PO_(4)-P,and SiO_(3)-Si concentrations in the mixed layer were 26.41±4.13,0.15±0.09,0.51±0.22,1.73±0.23,and 41.48±6.94μmol·L^(−1),respectively,and were higher than the relevant limitationconcentrations.The concentrations were generally bounded horizontally by the Southern Boundary(SB)of the Antarctic Circumpolar Current,the NO_(3)-N,NO_(2)-N,NH_(4)-N,and PO_(4)-P concentrations being higher northeast than southwest of the SB but the SiO_(3)-Si concentrations being higher southwest than northeast,indicating that the SB dominates nutrient distributions in themixed layer.The NO_(3)-N,NH_(4)-N,and PO_(4)-P concentrations gradually increased moving vertically down from the mixed layer to 200 m deep and then remained at 33.73±3.51,0.26±0.13,and 2.28±0.10μmol·L^(−1),respectively,to the bottom.The SiO_(3)-Si concentration increased as depth increased and reached a maximum in the bottom layer.The NO_(2)-N concentrationdecreased rapidly as depth increased and was~0μmol·L^(−1)at>150 m deep.Circumpolar Deep Water upwelling may cause high nutrient concentrations in shallower layers up to the 100 m layer between 62.5°S and 64°S.
基金Supported by the National Natural Science Foundation of China (Nos 40890153 and 40576016)
文摘With high-resolution conductivity-temperature-depth (CTD) observations conducted in Oct.-Nov. 2005, this study provides a detailed quasi-synoptic description of the North Pacific Tropic Water (NPTW), North Pacific Intermediate Water (NPIW) and Antarctic Intermediate Water (AAIW) in the western North Pacific. Some novel features are found. NPTW enters the western ocean with highest-salinity core off shore at 15°-18°N, and then splits to flow northward and southward along the western boundary. Its salinity decreases and density increases outside the core region. NPIW spreads westward north of 15°N with lowest salinity off shore at 21°N, but mainly hugs the Mindanao coast south of 12°N. It shoals and thins toward the south, with salinity increasing and density decreasing. AAIW extends to higher latitude off shore than that in shore, and it is traced as a salinity minimum to only 10°N at 130°E. Most of the South Pacific waters turn northeastward rather than directly flow northward upon reaching to the Mindanao coast, indicating the eastward shift of the Mindanao Undercurrent (MUC).
基金Supported by the National Key R&D Program of China(No.2016YFC1401702)the National Program on Global Change and Air-Sea Interaction(No.GASI-IPOVAI-01-01)+3 种基金the State Key Program of National Natural Science of China(No.41730534)the NSFC Innovative Group Grant(No.41421005)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1406401)ZANG Nan and WANG Fan.Janet SPRINTALL was supported by NOAA’s Climate Program Offi ce,Climate Variability and Predictability Program(No.NA17OAR4310257)。
文摘The dimensional and temporal distribution of Antarctic Intermediate Water(AAIW)and North Pacifi c Intermediate Water(NPIW)in the Philippine Sea were explored using Argo profi les and gridded Argo data.As the salinity minimum of intermediate water from mid-high latitude of the southern and northern hemisphere of the Pacifi c Ocean,the properties of AAIW and NPIW merge at about 10°N with diff erent properties in the Philippine Sea.The core of AAIW is located below 600 dbar with potential density of 27≤σθ≤27.3 kg/m 3 and salinity of 34.5≤S≤34.55.The core of NPIW is located between 300–700 dbar with potential density of 26.2≤σθ≤27 kg/m 3 and salinity of 34≤S≤34.4.The volume of AAIW and NPIW during January 2004 to December 2017 is negatively correlated.The time series of AAIW and NPIW is dominated by signifi cant periods of 6 and 8 months,respectively.The variations of AAIW and NPIW are mainly aff ected by volume transport through a 130°E section by the North Equatorial Current(NEC)and North Equatorial Undercurrent(NEUC).
基金supported by the National Key Research and Development Project of the Ministry of Science and Technology of China(Grant Nos.2016YFC1400302,2023YFC2812602)the National Natural Science Foundation of China(Grant No.41941005)。
文摘Conducting scientific drilling on subglacial lakes and obtaining samples of subglacial lake water holds great significance in unraveling the formation and evolution of Antarctic subglacial lakes and early Earth's life forms.Despite various approaches to access and directly sample subglacial water and sediments,clean access and exploration of subglacial lakes remain challenging.To address this concern,Jilin University has developed the RECoverable Autonomous Sonde(RECAS)prototype.This technology enables sampling and in-situ detection of subglacial lake water while being isolated from the surface,thus minimizing the risk of pollution.Laboratory tests,including downward and upward drilling,long-running,remote-control,and cold-environment assessments,were conducted to validate the sonde's principle and functionality.During the 38th Chinese National Antarctic Research Expedition,CHINARE(2021–2022 season),the RECAS prototype underwent testing on the flank region of Dalk glacier,10 km from Zhongshan Station in Antarctica.Three boreholes with depths of 200.3,183.2,and 133.5 m were successfully drilled,with the refrozen meltwater sealing the boreholes during the process.Approximately 600 mL of melted water samples were collected from each hole.Throughout the drilling tests,all systems of the RECAS prototype performed within the expected ranges.
基金supported by the National Natural Science Foundation of China (Grant No. 41006114)the National Science and Technology Major Project (Grant No. 2012YQ12003907)+2 种基金the National Key Basic Research Program of China (Grant Nos. 2012CB417401 and 2013CB956202)the CAS Strategic Priority Research Program (Grant No. XDA11010101)the NSFC-Shandong Joint Fund for Marine Science Research Center (Grant No. U1406401)
文摘A streamfunction EOF method is applied to a time series of hydrographic sections in the Southern Ocean south of Australia to study water mass variations. Results show that there are large thermohaline variations north of the Subantarctic Front (SAF) at 300–1500 dbar level, indicating upwelling and downwelling of the Antarctic Intermediate Water (AAIW) along isopycnal surfaces. Based on the latest altimeter product, Absolute Dynamic Topography, a mechanism due to frontal wave propagation is proposed to explain this phenomenon, and an index for frontal waves is defined. When the frontal wave is in positive (negative) phase, the SAF flows northeastward (southeastward) with the fresh AAIW downwelling (upwelling). Such mesoscale processes greatly enhance cross-frontal exchanges of water masses. Spectral analysis shows that frontal waves in the Southern Ocean south of Australia are dominated by a period of about 130 days with a phase speed of 4 cm/s and a wavelength of 450 km.