Primary production, bacterial production, par-ticulate organic carbon fluxes and organic carbon burial rates were quantified during the summer period of 1999 in the Arctic Ocean via 14C uptake, 3H uptake, 234Th/238U d...Primary production, bacterial production, par-ticulate organic carbon fluxes and organic carbon burial rates were quantified during the summer period of 1999 in the Arctic Ocean via 14C uptake, 3H uptake, 234Th/238U disequilibrium and 210Pbex dating, respectively. The integrated primary production in the water column was as high as 197 mmolC/(m2·d) in the Chukchi shelf and was 3.8 mmolC/(m2·d) in the Canada Basin. These rates are higher than those reported previously. The ratios of bacterial production to primary production in the study region were higher than 0.5, indicating that microbial activity is not depressed but important in cold Arctic waters. 234Th/238U dis-equilibria were evident at the station in the Canada Basin. The presence of significant 234Th deficiency suggested that scavenging and removal processes are also important to bio-geochemical cycles of trace elements in the Arctic Ocean. Particulate organic carbon export flux was estimated to be 1.0 mmolC/(m2·d). Measurements of sediment展开更多
Based on radar penetrating measurements and analysis of sea ice in the Arctic Ocean, the potential of radar wave to measure sea ice thickness and map the morphology of the under-side of sea ice is investigated. The re...Based on radar penetrating measurements and analysis of sea ice in the Arctic Ocean, the potential of radar wave to measure sea ice thickness and map the morphology of the under-side of sea ice is investigated. The results indicate that the radar wave can penetrate Arctic sum-mer sea ice of over 6 m in thickness; and the propagation velocity of the radar wave in sea ice is in the range of 0.142 m·ns-1 to 0.154 m·ns-1. The radar images display the roughness and mi-cro-relief variation of sea ice bottom surface. These features are closely related to sea ice types, which show that radar survey may be used to identify and classify ice types. Since radar images can simultaneously display the linear profile features of both the upper surface and the underside of sea ice, we use these images to quantify their actual linear length discrepancy. A new length factor is suggested in relation to the actual linear length discrepancy in linear profiles of sea ice, which may be useful in the further study of the area difference between the upper surface and bottom surface of sea ice.展开更多
The upper ocean thermohaline structures in the region of the Chukchi Plateauare analyzed with the hydrographic data collected by the Chinese National Arctic Research Expeditionin the summer of 2003. Three types of the...The upper ocean thermohaline structures in the region of the Chukchi Plateauare analyzed with the hydrographic data collected by the Chinese National Arctic Research Expeditionin the summer of 2003. Three types of the Pacific-origin water were found in the upper ocean,Alaska Coastal Water (ACW), summer Bering Sea Water (sBSW) and winter Bering Sea Water (wBSW) areindicated by two maximums temperature and one minimum temperature, piling up from the upper to thelower respectively. The extreme warm ACW with a maximum temperature of 1.62℃ was found in thesouthwestern Canada Basin at a depth of about 50 m. A pathway of the ACW into the basin from itsadjacent area did not existed in the expedition period. So it is speculated that the extreme warmfeature of the ACW was formed locally in 2003. The relative weak ACW occurred to the east of theChukchi Cap and in the southern Chukchi Abyssal Plain. The latter one might originate from a warmdownwelling that existed in a small canyon at the shelf break of the Chukchi Sea. The sBSW withoutthe ACW was found only at the southwestern flank of the Chukchi Cap. The ACW and the sBSW were notfound in the northernmost station at 81°N,which indicates the north boundary of the upperPacific-origin water in the Canada Basin. The wBSW, which existed in all deep stations, was exactlyuniform at temperature. The difference of the core potential temperature of the wBSW in the deepregions is only 0.08℃.展开更多
Arctic sea ice cover has decreased dramatically over the last three decades. This study quanti?es the sea ice concentration(SIC) trends in the Arctic Ocean over the period of 1979–2016 and analyzes their spatial and ...Arctic sea ice cover has decreased dramatically over the last three decades. This study quanti?es the sea ice concentration(SIC) trends in the Arctic Ocean over the period of 1979–2016 and analyzes their spatial and temporal variations. During each month the SIC trends are negative over the Arctic Ocean, wherein the largest(smallest) rate of decline found in September(March) is-0.48%/a(-0.10%/a).The summer(-0.42%/a) and autumn(-0.31%/a) seasons show faster decrease rates than those of winter(-0.12%/a) and spring(-0.20%/a) seasons. Regional variability is large in the annual SIC trend. The largest SIC trends are observed for the Kara(-0.60%/a) and Barents Seas(-0.54%/a), followed by the Chukchi Sea(-0.48%/a), East Siberian Sea(-0.43%/a), Laptev Sea(-0.38%/a), and Beaufort Sea(-0.36%/a). The annual SIC trend for the whole Arctic Ocean is-0.26%/a over the same period. Furthermore, the in?uences and feedbacks between the SIC and three climate indexes and three climatic parameters, including the Arctic Oscillation(AO), North Atlantic Oscillation(NAO), Dipole anomaly(DA), sea surface temperature(SST), surface air temperature(SAT), and surface wind(SW), are investigated. Statistically, sea ice provides memory for the Arctic climate system so that changes in SIC driven by the climate indices(AO, NAO and DA) can be felt during the ensuing seasons. Positive SST trends can cause greater SIC reductions, which is observed in the Greenland and Barents Seas during the autumn and winter. In contrast, the removal of sea ice(i.e., loss of the insulating layer) likely contributes to a colder sea surface(i.e., decreased SST), as is observed in northern Barents Sea. Decreasing SIC trends can lead to an in-phase enhancement of SAT, while SAT variations seem to have a lagged in?uence on SIC trends. SW plays an important role in the modulating SIC trends in two ways: by transporting moist and warm air that melts sea ice in peripheral seas(typically evident inthe Barents Sea) and by exporting sea ice out of the Arctic Ocean via passage展开更多
基金This work was supported by the Chinese First Arctic Expedition Foundation the National Natural Science Foundation of China (Grant No. 40076024).
文摘Primary production, bacterial production, par-ticulate organic carbon fluxes and organic carbon burial rates were quantified during the summer period of 1999 in the Arctic Ocean via 14C uptake, 3H uptake, 234Th/238U disequilibrium and 210Pbex dating, respectively. The integrated primary production in the water column was as high as 197 mmolC/(m2·d) in the Chukchi shelf and was 3.8 mmolC/(m2·d) in the Canada Basin. These rates are higher than those reported previously. The ratios of bacterial production to primary production in the study region were higher than 0.5, indicating that microbial activity is not depressed but important in cold Arctic waters. 234Th/238U dis-equilibria were evident at the station in the Canada Basin. The presence of significant 234Th deficiency suggested that scavenging and removal processes are also important to bio-geochemical cycles of trace elements in the Arctic Ocean. Particulate organic carbon export flux was estimated to be 1.0 mmolC/(m2·d). Measurements of sediment
基金the National Natural Science Foundation of China(Grant No.40071022)the Ministry of Science and Technology of China(Grant No.2001DIA50040)+1 种基金Chinese Arctic Expedition Foundation and the Laboratory Foundation of Ice Core and Cold Region Environment,Cold and Arid Regions Environmental and Engineering Institutethe ChineseAcademy of Sciences(Grant No.BX2001-04).
文摘Based on radar penetrating measurements and analysis of sea ice in the Arctic Ocean, the potential of radar wave to measure sea ice thickness and map the morphology of the under-side of sea ice is investigated. The results indicate that the radar wave can penetrate Arctic sum-mer sea ice of over 6 m in thickness; and the propagation velocity of the radar wave in sea ice is in the range of 0.142 m·ns-1 to 0.154 m·ns-1. The radar images display the roughness and mi-cro-relief variation of sea ice bottom surface. These features are closely related to sea ice types, which show that radar survey may be used to identify and classify ice types. Since radar images can simultaneously display the linear profile features of both the upper surface and the underside of sea ice, we use these images to quantify their actual linear length discrepancy. A new length factor is suggested in relation to the actual linear length discrepancy in linear profiles of sea ice, which may be useful in the further study of the area difference between the upper surface and bottom surface of sea ice.
基金supported by the National Natural Science Foundation of China under contract Nos 40306005 and 40376007.
文摘The upper ocean thermohaline structures in the region of the Chukchi Plateauare analyzed with the hydrographic data collected by the Chinese National Arctic Research Expeditionin the summer of 2003. Three types of the Pacific-origin water were found in the upper ocean,Alaska Coastal Water (ACW), summer Bering Sea Water (sBSW) and winter Bering Sea Water (wBSW) areindicated by two maximums temperature and one minimum temperature, piling up from the upper to thelower respectively. The extreme warm ACW with a maximum temperature of 1.62℃ was found in thesouthwestern Canada Basin at a depth of about 50 m. A pathway of the ACW into the basin from itsadjacent area did not existed in the expedition period. So it is speculated that the extreme warmfeature of the ACW was formed locally in 2003. The relative weak ACW occurred to the east of theChukchi Cap and in the southern Chukchi Abyssal Plain. The latter one might originate from a warmdownwelling that existed in a small canyon at the shelf break of the Chukchi Sea. The sBSW withoutthe ACW was found only at the southwestern flank of the Chukchi Cap. The ACW and the sBSW were notfound in the northernmost station at 81°N,which indicates the north boundary of the upperPacific-origin water in the Canada Basin. The wBSW, which existed in all deep stations, was exactlyuniform at temperature. The difference of the core potential temperature of the wBSW in the deepregions is only 0.08℃.
基金Supported by the National Natural Science Foundation of China(No.41406215)the NSFC-Shandong Joint Fund for Marine Science Research Centers(No.U1606401)+2 种基金the Qingdao National Laboratory for Marine Science and Technology,the Postdoctoral Science Foundation of China(No.2014M561971)the Open Funds for the Key Laboratory of Marine Geology and Environment,Institute of Oceanology,Chinese Academy of Sciences(No.MGE2013KG07)the Natural Science Foundation of Jiangsu Province of China(No.BK20140186)
文摘Arctic sea ice cover has decreased dramatically over the last three decades. This study quanti?es the sea ice concentration(SIC) trends in the Arctic Ocean over the period of 1979–2016 and analyzes their spatial and temporal variations. During each month the SIC trends are negative over the Arctic Ocean, wherein the largest(smallest) rate of decline found in September(March) is-0.48%/a(-0.10%/a).The summer(-0.42%/a) and autumn(-0.31%/a) seasons show faster decrease rates than those of winter(-0.12%/a) and spring(-0.20%/a) seasons. Regional variability is large in the annual SIC trend. The largest SIC trends are observed for the Kara(-0.60%/a) and Barents Seas(-0.54%/a), followed by the Chukchi Sea(-0.48%/a), East Siberian Sea(-0.43%/a), Laptev Sea(-0.38%/a), and Beaufort Sea(-0.36%/a). The annual SIC trend for the whole Arctic Ocean is-0.26%/a over the same period. Furthermore, the in?uences and feedbacks between the SIC and three climate indexes and three climatic parameters, including the Arctic Oscillation(AO), North Atlantic Oscillation(NAO), Dipole anomaly(DA), sea surface temperature(SST), surface air temperature(SAT), and surface wind(SW), are investigated. Statistically, sea ice provides memory for the Arctic climate system so that changes in SIC driven by the climate indices(AO, NAO and DA) can be felt during the ensuing seasons. Positive SST trends can cause greater SIC reductions, which is observed in the Greenland and Barents Seas during the autumn and winter. In contrast, the removal of sea ice(i.e., loss of the insulating layer) likely contributes to a colder sea surface(i.e., decreased SST), as is observed in northern Barents Sea. Decreasing SIC trends can lead to an in-phase enhancement of SAT, while SAT variations seem to have a lagged in?uence on SIC trends. SW plays an important role in the modulating SIC trends in two ways: by transporting moist and warm air that melts sea ice in peripheral seas(typically evident inthe Barents Sea) and by exporting sea ice out of the Arctic Ocean via passage
