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Progress of diversity of subglacial ecosystem and their response to the climate change Ma Hongmei, Yan Wenkai, Cheng Yongqian, Zhang Yu, Xiao Xiang 2017, 29 (1):  1-10.  DOI: 10.13679/j.jdyj.2017.1.001 Abstract ( 799 )   PDF (598KB) ( 1108 )   Investigation of the characteristics and adaptive strategies of life beneath ice sheets and glaciers is at the forefront of polar research. Many studies have reported that liquid water and organic matter coexist in subglacial regions, providing a suitable microbial habitat. Furthermore, the presence of microbes beneath polar glaciers can modulate geochemical weathering processes, although this is likely to be affected by climate-forced environmental changes. Considering the diversity of ecosystems beneath polar glaciers and their responses to climate change, this study elucidated the microbial characteristics, their possible origins, the mechanisms of the biogeochemical processes occurring beneath polar glaciers, and the influences of subglacial microbial life on the C and N cycles. The objective was to provide a reference resource for future subglacial research. Related Articles | Metrics

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Review of Research Progress of Tide Measuring and Influence of Regional Tide on Ice Shelf Surface Velocity in Antarctica Ma Xuwen, Tian Yixiang, Ye Wenkai 2017, 29 (1):  11-22.  DOI: 10.13679/j.jdyj.2017.1.011 Abstract ( 761 )   PDF (1321KB) ( 1091 )   The Antarctic regional tide is the main influential factor in estimations of the Antarctic ice sheet mass balance and ice shelf surface velocity, which makes it of considerable importance for research on ice shelf collapse and global warming. Methods for determining the Antarctic tide have developed from real-time measurement into techniques based on satellite altimetry, remote sensing monitoring, and model predictions. Recent research has demonstrated a correlation between the tidal cycle and ice shelf surface velocity. For example, the surface velocities of the Filcher-Ronne and Ross ice shelves reach maxima during spring tides and minima during neap tides. This paper summarizes the association of tidal characteristics with the surface velocity and elevation changes of typical Antarctic ice shelves. It provides a basis for future studies focusing on the tidal variations of West Antarctica, the Antarctic Peninsula, and the data-sparse areas of East Antarctica, which are vital for building an Antarctic tidal database and for increasing model accuracy. Related Articles | Metrics

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Geochemical Characteristics of Rare Earth Elements in The Sediments of Prydz Bay, Antarctica Li Guogang, Ji Youjun, Li Yunhai, Leng Qinuan, Bu Ruyuan, Li Yixin 2017, 29 (1):  23-32.  DOI: 10.13679/j.jdyj.2017.1.023 Abstract ( 769 )   PDF (2879KB) ( 978 )   Based on three short sediment cores collected in Prydz Bay (Antarctica) during the 29th Chinese National Antarctic Research Expedition, the rare earth element (REE) contents, sediment grain sizes, and biogenic proxies were determined to discuss the pattern and controlling factors of the REE distribution. The results showed that the REEs of Prydz Bay sediments vary in content but have similar shale-normalized distribution patterns, i.e., rich in light REEs, to upper continental crust and metamorphic rocks from Zhongshan Station, indicating they have the same terrigenous provenance. Based on the sediment grain size, major elements, and biosourced proxies, it is suggested that sediment provenance is the major controlling factor behind REE composition. Moreover, biological action might dilute the REE concentration, making the grain-size effect invalid. The REE proxies in the sediment profile were almost stable with depth, reflecting similar terrigenous inputs and depositional environments on the century scale. In addition, the δCe values generally decreased downward, suggesting a gradual decreasing trend in oxidability within the sediment core. Related Articles | Metrics

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Temporal Trends and Ecological Risks of Eight Typical Trace Metals and Three Platinum Group Metals in the Arctic Yan Jing, Lu Zhibo, Zhang Jie 2017, 29 (1):  33-44.  DOI: 10.13679/j.jdyj.2017.1.033 Abstract ( 723 )   PDF (3186KB) ( 788 )   The pathway for trace metals entering the Arctic region includes ocean input, atmospheric transportation, river input, land runoff, and atmospheric deposition. This study analyzed the temporal trends of several trace metals in a variety of environmental media from the Arctic region. Among these trace metals, eight typical trace metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) have been the focus of previous environmental monitoring. However, mining and smelting activities and the application of automobile catalysts have led to platinum group metals (including Pt, Pd, and Rh) potentially becoming serious pollutants. The results of this study showed that Pb and Hg, attributable to industrial development, present variation trends distinct from Cd, Zn, and Cu in the environmental media, and that Pt, Pd, and Rh concentrations evidence global pollution resulting from large-scale transportation from areas of human activity. The potential risks associated with As, Cd, Cr, Cu, Hg, Pb, and Zn are also assessed based on previously published scientific data on the levels of trace metals in surface sediments from areas within the Arctic Sea. It is concluded that concentrations of As, Cd, and Cu in the sediments across a large part of the Arctic Sea probably pose a threat to marine organisms. Concentrations of Hg, MeHg, and Zn in the organs of Arctic animals have been reported to be accumulating with trophic level, and this evidence of definite toxicity requires further study. Related Articles | Metrics

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Spatial Distribution Characteristics of SO42– and MSA in Surface Snow Along the Traverse Route from Zhongshan Station to Dome A, East Antarctica Yu Jinhai, Li Yuansheng, Ma Hongmei, Shi Guitao, Ma Tianming, An Chunlei, Jiang Su 2017, 29 (1):  45-55.  DOI: 10.13679/j.jdyj.2017.1.045 Abstract ( 864 )   PDF (3683KB) ( 1032 )   The traverse route from Zhongshan Station to Dome A in East Antarctica is one of the main expedition routes of the International Trans-Antarctic Scientific Expedition (ITASE), which has considerable global scientific significance. Following the inland ice sheet scientific expedition of the 31st CHINARE, surface snow samples collected at 10-km intervals along this route were analyzed using ion chromatography and content concentrations of sulfur compounds (SO42– and MSA) were obtained. The nssSO42– and MSA contents along the traverse route presented no obvious overall trend of decrease in spatial variation with increasing distance from the coast, but regional trends were detected. Significant correlation was found between nssSO42– and MSA in the inland plateau area of Dome A, with a linear relation of [MSA] = 0.115 8 × [nssSO42– ] – 1.149 7 (r2 = 0.75). The MSA/nssSO42– ratio along the traverse route was also calculated (range: 0.04–0.47; mean: 0.14), which revealed that the ratio in coastal areas was higher than inland areas. Different sources or the wind field streamlines of the transect might be the main reasons for the finding of inconsistently higher MSA/nssSO42– ratios at lower temperatures. Further research on the sulfur compounds along the transect in this study would be enhanced by consideration of the climatic environment based on ice core records of nssSO42– and MSA. Related Articles | Metrics

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Baseline trends of atmospheric CO2, CH4, and N2O concentrations in Antarctica Sun Shumeng, Zheng Xiangdong, Bian Lingen 2017, 29 (1):  56-65.  DOI: 10.13679/j.jdyj.2017.1.056 Abstract ( 726 )   PDF (1211KB) ( 825 )   The long-term baseline trends of the atmospheric greenhouse gases (GHGs) CO2 (including δ13C-CO2and δ18O-CO2 abundances), CH4, and N2O in Antarctica were compared with those from other latitudinal bands. The results suggest that global concentrations of GHGs increase with latitude from south to north, with the lowest (highest) abundance in Antarctica. The overall long-term trends and annual growth rates of GHGs in Antarctica are consistent with the global values, although the trends or growth rates of a concrete gas in Antarctica may quantitatively differentiate from the global values.  During 1958–2014, the average growth rate of CO2 concentration in Antarctica (1.43 ± 0.59) mg·L–1·a–1 was lower than that in the tropics (1.51 ± 0.72) mg·L–1·a–1. Conversely, the average growth rate of CO2 concentration in Antarctica during the periods 1980–2014 and 2000–2014 were higher than that in the Southern Hemisphere Middle (SHM) latitudinal band but lower than that in the Northern Hemisphere (NH). The trends of δ13C-CO2 and δ18O-CO2 abundance reflect the effects of fossil fuel combustion and global-scale processes on global CO2  variations. During 1983–2014, the overall growth rate of CH4 concentration in Antarctica (1.43 ± 0.59) µg·L–1·a–1 was lower than that in the NH (6.5 ± 5.6) µg·L–1·a–1, but higher than that in the tropics (5.6 ± 5.3) µg·L–1·a–1 and the SHM (6.1 ± 4.9) µg·L–1·a–1. This confirmed the NH as the largest source of CH4, and the tropics and SHM as substantial CH4 sinks via OH oxidation. The overall average growth rate of atmospheric N2O in Antarctica was (0.87 ± 0.15) µg·L–1·a–1 during 2005–2013; lower (higher) than that in the NH (tropics) and very close to that in the SHM. The difference in the growth rate reflects anthropogenic emissions and the latitude-dependence of the vertical structure of the surface boundary layer, which has obvious influence on surface-level behavior of N2O. Related Articles | Metrics

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Microzooplankton grazing impact in Southern Ocean and temperate sea area around during austral summer Zhang Ye, Li Chaolun, Yang Guang, Wang Yanqing, Tao Zhencheng 2017, 29 (1):  66-73.  DOI: 10.13679/j.jdyj.2017.1.066 Abstract ( 744 )   PDF (1575KB) ( 789 )   Microzooplankton play an important role in marine food web. In order to clarify grazing impact of microzooplankton on phytoplankton, dilution incubations were carried out in Southern Ocean and temperate sea area during austral summer, 2012-2013. Results showed that microzooplankton grazing rates were in the range of 0.07d-1–1.29d-1, while phytoplankton growth rate were 0.04d-1–0.89d-1. Accordingly, 6.4%–72.5% of the phytoplankton stock and a high range of 14%–776.9% primary production were grazed by microzooplankton. Although the microzooplantkon grazing rates might be overestimated, microzooplankton have a significant role in controlling phytoplankton in Southern Ocean and temperate sea area in austral summer. Related Articles | Metrics

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Influence of irradiation on the paralytic shellfish toxin content and profiles of Alexandrium tamarense isolated #br# from the Arctic waters Lv Yihua, Xiong Xiaofei, Wu Jiaxin, Yang Zhenxiong, Yang Xi, Dong Yanhong 2017, 29 (1):  74-81.  DOI: 10.13679/j.jdyj.2017.1.074 Abstract ( 714 )   PDF (3260KB) ( 750 )   A comparative analysis of the physiology and toxin composition was performed on a suite of clonal cultures of the potentially toxic dinoflagellate Alexandrium tamarense. These were established from resting cysts or vegetative cells isolated from sediment or the water taken from the coasts of Greenland, Iceland, Chukchi Sea and Gulf of Maine. Maximum growths were observed between 38 µmol·m–2·s–1 and 91 µmol·m–2·s–1. No dcGTX2 was detected in all 12 isolates, toxin content significant variation was observed. In general, toxin contents and toxicity were generally highest at higher irradiation. This may indicate that the genetically determined toxin profiles in A. tamarense species are more complex than previously appreciated. Related Articles | Metrics

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A preliminary study on the population amount and functional activity of soil nitrogen cycle microbes in Fildes#br# Peninsula of Antarctica Liu Jie, Zhang Dandan, Dong Longlong, Wang Nengfei 2017, 29 (1):  82-89.  DOI: 10.13679/j.jdyj.2017.1.082 Abstract ( 726 )   PDF (579KB) ( 878 )   Fildes Peninsula is located at the southern end of King George Island in Antarctica. It is an ideal place to study Antarctic ecology and biological resources because of its unique geographical location and ecological environment. In this study, three different soil sample types were collected from the peninsula. The population sizes of soil nitrogen cycle microbes and their functional activities were determined using the Most Probable Number (MPN) and conventional Griess and Nessler’s active color test methods. The experimental results were also comprehensively analyzed regarding the ecology and physicochemical properties of the soil. The objectives were to develop a preliminary understanding of the soil nitrogen cycle microbes of Fildes Peninsula, and to prepare a scientific foundation for further study within this area. The results showed that the population sizes of nitrogen cycle microbes in the 13 collected soil samples in descending order were ammonification bacteria > denitrifying bacteria > nitrobacteria or nitrogen-fixing bacteria. Except for a few samples, most exhibited differing degrees of nitrification, denitrification, and ammonification activity. Furthermore, all soil samples had relatively high levels of ammonification bacteria and ammonification activity. The population sizes of denitrifying bacteria and the denitrifying activity of hillslope soils were higher than soils occupied by animals and plants. Although lower levels of nitrobacteria existed in soils occupied by animals and plants, they showed higher nitrifying activity, which might indicate the existence of strains with efficient function. Furthermore, the population sizes of nitrobacteria and the nitrifying activity of hillslope soils varied. This study provides a preliminary reference for further research of the characteristics of nitrogen cycling microbes in Antarctica. Related Articles | Metrics

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Estimation of sea ice freeboard from CryoSat-2 data in the Arctic Greenland Sea Wei Xin, Li Fei, Zhang Shengkai, Yuan Lexian, Zuo Yaowen, Zhu Tingting, Xiao Feng 2017, 29 (1):  90-100.  DOI: 10.13679/j.jdyj.2017.1.090 Abstract ( 722 )   PDF (7323KB) ( 574 )   The Arctic region has an important role in global climate, and changes in Arctic sea ice represent one of the most visible consequences of climate change. The Greenland Sea is one of the areas of the Arctic that have undergone drastic changes. In this study, CryoSat-2 radar altimeter data were used to retrieve the distribution of sea ice freeboard in the Greenland Sea. The sea ice thicknesses converted from the freeboard were validated using the Beaufort Gyre Experiment Program upward-looking sonar data. The results showed that both the freeboard and the extent of sea ice in the Greenland Sea have remarkable seasonal variations. It was found that the freeboard and extent of the sea ice kept increasing after the Greenland Sea had entered the frozen season in October. The average sea ice freeboard reached a maximum of 0.2 m by February. Then, the sea ice began to melt, and as the sea ice extent continued to decrease, the sea ice freeboard reached a minimum of 0.13 m by September. Related Articles | Metrics

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Characteristics of ELDI varying with solar activity in polar region from observations of EISCAT/ESR radars Huang Dingjuan, Cai Hongtao, Li Fei, Hu Kun, Li Ying, Yu Yao, Ma Shuying 2017, 29 (1):  101-110.  DOI: 10.13679/j.jdyj.2017.1.101 Abstract ( 855 )   PDF (1012KB) ( 880 )   This study investigated the characteristics of polar E-Layer Dominated Ionosphere (ELDI) events under various solar activities, based on field-aligned measurements from the EISCAT (EISCAT Tromsø UHF) and ESR (EISCAT Svalbard Radar) instruments during 1999–2011. It was found that ELDI occurrences exhibit clear reliance on solar activity. During solar maximum, ELDI events appear more frequently at the EISCAT site (at the auroral latitude) than at the ESR site (at cusp latitude), and vice versa during solar minimum. ELDI events are rarely observed by both radars in summer, which illustrates few effects of solar activity. Seasonal variations of ELDI occurrences at both sites during solar maximum are in accordance with those during solar minimum., i.e., ELDI occurrences are higher in winter and early spring than in other seasons, especially summer. On the occurrence of ELDI events, the duration of the event and the thickness of the ionospheric E-layer show remarkable variations under different solar activity conditions: the duration is shorter and the thickness is greater during solar maximum, while NmE/NmF2 and HmE appear less variable. Related Articles | Metrics

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Hydrographic structure and inter-annual variations of Bering Sea in summer Zuo Fei, Li Bingrui, Wu Chengxiang, Jia Wang, Li Yuansheng 2017, 29 (1):  111-123.  DOI: 10.13679/j.jdyj.2017.1.111 Abstract ( 910 )   PDF (12794KB) ( 653 )   Based on conductivity–temperature–depth (CTD) data obtained by the Chinese National Arctic Research Expeditions (2008, 2010, 2012, and 2014), in combination with shared historical data, the water mass, upper-ocean heat content, net heat flux change, wind field, and sea level pressure were analyzed to investigate the interannual variability of the hydrologic structural characteristics of the Bering Sea. It was found that the waters of the Bering Sea could be divided into four masses: Bering Upper Water (BUW), Bering Middle Water (BIW), Bering Deep Water (BDW), and Bering Shelf Water (BSW). Variations of temperature and salinity were concentrated mainly in the upper water. In July 2012, the sea surface temperature (SST) was below normal, whereas in July 2014, strong positive SST anomalies developed. These abnormal phenomena resulted because of lower or higher heat content. We investigated the reasons for the SST anomaly in July 2014 and found that the mechanism was completely different from basin to shelf. The higher SST of shelf waters was mainly caused by higher cumulative net heat flux, whereas in the basin, it was due to unusually strong and persistent high pressure. This meant that the sea surface wind stress curl was enhanced, which caused continuous warm advection, and strong Ekman pumping, function that led to warming of the upper water. Related Articles | Metrics

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Management strategy of the observer coverage under the scheme of international scientific observation for Antarctic krill fishery and performance review of observation program in Chinese krill fishery Zuo Tao, Zhu Jiancheng, Wang Xinliang, Shi Yongqiang 2017, 29 (1):  124-132.  DOI: 10.13679/j.jdyj.2017.1.124 Abstract ( 921 )   PDF (1218KB) ( 989 )   This paper outlines the main elements of observer coverage in the Scheme of International Scientific Observation (SISO) of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), and reviews the performance outcomes of the scientific observation program for the Chinese krill fishery during the past six fishing seasons. The objective is to help members of the Chinese krill fishing fleet better understand and properly implement CCAMLR policies in the convention area. The SISO is one of the most important parts of the monitoring, control, and surveillance system of CCAMLR. It has a series management procedure including observer designation, observation task and function definition, assessment, and operational review. It is mandatory for all fisheries in the CCAMLR convention area to carry an observer. The observer coverage in the SISO is designed and operated at three levels: sampling of vessels, sampling of hauls among vessels, and sampling within hauls. Since commencing a krill fishery program in the 2009/10 fishing season, China has made every effort to ensure both maximum possible coverage and high-quality scientific observation. During the past six fishing seasons of 2009—2015, nearly 30 scientific observers have been deployed onboard 19 of the 23 operating vessels. The annual observed coverage of fishing days varied from 81%–100% (mean: 94%), and the annual vessel coverage ranged from 66%–100% (six year mean: 82%), greater than the minimum 50% requirement. To improve the quality and capability of Chinese observers in response to possible future adjustments of the management strategy regarding observer coverage, we suggest organizing an open and transparent observer training program using national and international experts. In addition, the recruitment of international observers would be a flexible and alternative way to overcome temporary shortages of qualified observer personnel. Related Articles | Metrics

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Study of polar science and technology system of major polar countries——Take the U. S., Russia and Australia as examples Zhang Lulu, Zang Jingjing 2017, 29 (1):  133-141.  DOI: 10.13679/j.jdyj.2017.1.133 Abstract ( 774 )   PDF (529KB) ( 1391 )   The polar science and technology system which leads the country polar scientific research has aroused wide attention in many countries around the world. Polar science and technology systems constitute the structural system and organization of polar science and technology research with the management and organizational setup, scope of responsibility, and ownership. Scientific and reasonable polar science and technology system is the premise and foundation to promote the development of polar science and technology. This article mainly analyses the representative polar power of the polar science and technology systems developed by countries such as the U.S., Russia, and Australia. It also summarizes the polar system of each country. Lastly, it focuses on the current status of the polar science and technology system of China, and it explores the direction of future reform of our polar cause in “Thirteenth Five-Year Plan” period to deepen the comprehensive reform which will gradually form a relatively perfect polar science and technology system which is suitable for our national condition. Related Articles | Metrics

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Overview of the WAN construction and service at the Chinese polar research stations Shan Xuewu, Jiang Tianle, Wang Dali, Lv Yuan, Lu Dahai, Li Yingxu 2017, 29 (1):  142-150.  DOI: 10.13679/j.jdyj.2017.1.142 Abstract ( 715 )   PDF (2560KB) ( 982 )   Through the construction of a satellite communication network system during the Chinese polar expedition of the “Tenth Five-Year Plan,” the capacity of the wide area network (WAN) communications at Chinese Antarctic research stations has been greatly improved. This article systematically addresses the status of the WAN communications at two Chinese Antarctic stations, describing the construction of the satellite communication links, computer network systems building, and the service provided by the system. Furthermore, it also elucidates the satellite communications, local area network, and VOIP technology that constitute part of the system. Finally, the plan for the future construction of additional communication technologies for use with polar expeditions is outlined. Related Articles | Metrics

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Progress of geological and geophysical scientific investigations of Arctic Ocean Zhang Huatian, Li Jianghai, Wang Luo, Liu Zhonglan 2017, 29 (1):  151-162.  DOI: 10.13679/j.jdyj.2017.1.151 Abstract ( 788 )   PDF (9600KB) ( 596 )   Perennial coverage of sea ice has meant that the Arctic Ocean is much less well explored than other oceans. Systematic Arctic Ocean exploration began during the 1990s, and the commissioning of new investigative equipment and methods such as icebreakers and submarines has meant that researchers have been able to select research targets. This has led to the success of several geological and geophysical scientific investigation of the Arctic Ocean, including the Scientific Ice Expeditions, Arctic Mid-Ocean Ridge Expedition, Arctic Gakkel Vents Expedition, and IODP 302. This paper reviews several important systematic geological and geophysical expeditions of the Arctic Ocean, and it summarizes the leading scientific problems, i.e., the properties and evolution of major Arctic tectonic units, structural and metallogenetic characteristics of an ultraslow spreading ridge, and Cenozoic evolution of the paleo-Arctic Ocean. Based on our review, three primary conclusions were drawn: (1) investigation methods are the key element constraining the development of Arctic Ocean exploration, (2) icebreakers combined with regular investigating methods constitute the major trend of development in Arctic Ocean exploration, (3) near-bottom investigation helps solve the geological problems of the Arctic Ocean. Related Articles | Metrics

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Analysis on spatiotemporal variations of Antarctic sea ice during 2002—2011 Shen Xiaoyi, Ke Changqing, Zhang Jie 2017, 29 (1):  163-171.  DOI: 10.13679/j.jdyj.2017.1.163 Abstract ( 813 )   PDF (3602KB) ( 1347 )   Based on daily Antarctic sea ice concentration data acquired by AMSR-E during 2002—2011, this study calculated the extent and area of sea ice and analyzed the spatiotemporal characteristics of its variability over different timescales. The results revealed increases of 3.64% decade–1 in sea ice extent and 3.8% decade–1 in sea ice area. The derived 10-year trend of sea ice for the entire Antarctic sea ice area was significantly positive, and the year of 2008 experienced the maximum sea ice area. Regionally, increases were found in the Ross Sea, Weddell Sea, and Western Pacific sectors, and small decreases were detected in the Indian Ocean and the Bellingshausen Sea and Amundsen Sea sectors. Seasonally, both sea ice extent and sea ice area in the Antarctic are at a minimum in summer and a maximum in winter. In the same season, the various regions have different ranges of variation in sea ice area. First-year ice is mainly distributed around the Antarctic mainland, except for the Weddell Sea sector, and the trend of sea ice area is generally positive (0.1×106 km2·a–1), which is in marked contrast to the decrease in the multiyear ice area of –0.05×106 km2·a–1; most multiyear ice is distributed within the Weddell Sea sector. The change of sea ice extent is correlated negatively with temperature. Related Articles | Metrics

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Analysis of research hotspots in oceanography of the United States based on science citation index expanded from 2010 to 2014 Liu Yanhua, Hua Weina, Chang Liyan 2017, 29 (1):  172-181.  DOI: 10.13679/j.jdyj.2017.1.172 Abstract ( 687 )   PDF (1790KB) ( 912 )   Based on SCI-E, we collated details of almost all documents regarding oceanography published in the United States from 2010 to 2014. By analyzing the co-occurrence frequency of 54 high-frequency keywords using SPSS software and a cluster analysis method, this study revealed the six oceanographic research hotspots of the United States from 2010 to 2014: ocean circulation dynamics, ocean disasters, application of science and technology methods in oceanography, ocean primary productivity, ocean pollution, and ocean biodiversity. Furthermore, a visualization map was constructed of the co-occurrence matrix of research hotpots and high-frequency author names, based on social network analysis, to identify the groups of authors associated with these research topics. Related Articles | Metrics