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Discovery and application of polar yeasts Lu Fengning, Zhang Yuanxing, Cai Menghao 2021, 33 (3):  315-324.  DOI: 10.13679/j.jdyj.20200059 Abstract ( 946 )   PDF (319KB) ( 1260 )   To adapt to the extreme polar environment, polar yeasts maintain their life through unique cold-adaptive strategies including production of antifreeze proteins, unsaturated fatty acids, extracellular polysaccharides, pigments, and cold-active enzymes. These products have great potential for commercial use, including applications in the fields of food, agriculture, medicine, textiles, and health. Although research has been conducted on polar yeasts for over a century, there are still knowledge gaps relating to their geographical distribution, diversity, and ecological function which need further exploration and development. In this paper, the discovery and application of polar yeasts are reviewed to provide a reference for further research and development of polar yeast product resources. References | Related Articles | Metrics

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Modeling of the SuperDARN polar ionospheric cross polar cap electric field using deep learning Li Ke, Liu Erxiao 2021, 33 (3):  325-336.  DOI: 10.13679/j.jdyj.20200058 Abstract ( 770 )   PDF (1004KB) ( 802 )   The Cross Polar Cap electric field (i.e. the ionospheric convective electric field) was calculated using ionospheric potential data (i.e. the Cross Polar Cap potential) from the Super Dual Auroral Radar Network (SuperDARN). Then, historical data for the convective electric field were introduced and the ionospheric electric field model was constructed using a multivariate linear regression algorithm and a back propagation neural network algorithm that used ionospheric electric field data from 2014. The accuracy and stability of the two models were verified using an independent dataset. The results show that the root mean square of the error between the model values and the measured values is in the range of 2.0 mV·m–1 to 3.5 mV·m–1, the mean absolute error is in the range of 1.5 mV·m–1 to 3.0 mV·m–1, and the linear correlation coefficient is greater than 0.6 and has a maximum of 0.9. At the same time, the historical data of convection electric field in the first 20 min were introduced as the input for the multivariate linear regression model and BP neural network model. These results show that the back propagation neural network model has better prediction performance than the multivariate linear regression model. References | Related Articles | Metrics

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Analysis of BDS-3 signal quality and basic positioning service around Antarctica Zhao Jian, An Jiachun, Ai Songtao, Wang Zemin, Zhu Lizhong, Song Xiangyu 2021, 33 (3):  337-350.  DOI: 10.13679/j.jdyj.20200051 Abstract ( 1011 )   PDF (1556KB) ( 1305 )   With the complete deployment of satellites, the service of the BeiDou Navigation Satellite System (BDS) has expanded from the Asia-Pacific region to the whole world, including polar regions. In this study, GPS and BDS-3 data from 2018 to 2020 were collected at Zhongshan Station, Great Wall Station, and Xuelong icebreaker that sailed around the Antarctica. The signal quality and positioning accuracy of BDS-3 in the Antarctica was assessed with the number of visible satellites, position dilution of precision, multipath error and signal-to-noise ratio, and standard point positioning accuracy. The results show that the number of BDS satellites visible in the Antarctica is between 4 and 20, and the satellite visibility and position dilution of precision of BDS in the Antarctica are better than those of GPS. The Medium Earth Orbit (MEO) multipath errors of BDS satellites are similar to those of GPS satellites, while the Geosynchronous Earth Orbit (GEO) and Inclined Geosynchronous Satellite Orbit (IGSO) satellites of BDS have large multipath error due to their low elevations in the polar region. In terms of positioning accuracy, the standard point positioning accuracy of BDS in the Antarctica is within 7 m, which meets the design requirements of BDS. Although BDS-3 constellation is still being updated, it has solved the problem of limited number of visible satellites in high latitudes and has significantly improved the positioning performance. The positioning accuracy of BDS at Great Wall Station at the beginning of 2020 was improved by 50% compared to that at the beginning of 2019. References | Related Articles | Metrics

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Modeling supraglacial river networks on the Greenland ice sheet using the topographic index Mao Wei, Lu Xin, Lu Yao, Yang Kang 2021, 33 (3):  351-362.  DOI: 10.13679/j.jdyj.20200048 Abstract ( 989 )   PDF (15973KB) ( 507 )   During the annual ablation period, a large amount of meltwater is transported to the margin of the Greenland ice sheet through supraglacial river networks, causing mass loss from the Greenland ice sheet. The dynamics of supraglacial river networks determine the flowpath and efficiency of meltwater routing, and significantly affect the mass balance of the Greenland ice sheet. As one of the key factors that determines the dynamics of supraglacial river networks, the control of the ice surface topography on the supraglacial river network’s dynamics remain unknown. In this study, we modeled the distribution of supraglacial river networks on a typical melting region of the southwest Greenland ice sheet (approximately 1800 km2) using the Topographic Wetness Index and the Height Above the Nearest Drainage method derived from the 32 m Arctic DEM. The modeling results were validated and compared with the frequency observations compiled from 29 scenes acquired from Sentinel-2 imagery at 10-m resolution and Landsat-8 imagery at 30-m resolution. The results show that the Topographic Wetness Index (TWI) and Height Above the Nearest Drainage (HAND) method can be used to model the spatial distribution of the Greenland ice sheet supraglacial river network with an overall accuracy greater than 72%; therefore, the spatial distribution of the supraglacial river network is mainly controlled by the ice surface topography. As shown here, applying topographic indices in the study of supraglacial hydrology can help to improve the understanding of supraglacial hydrological processes. References | Related Articles | Metrics

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Numerical simulation of ice sheets in the western region of Marie Byrd Land using Elmer/Ice Yang Shuhu, Xu Jiaxin, Xu Derui, Han Yanling, Zhang Yun, Hong Zhonghua 2021, 33 (3):  363-373.  DOI: 10.13679/j.jdyj.20200052 Abstract ( 928 )   PDF (10629KB) ( 654 )   The West Antarctic ice sheet has an important impact on global climate change and sea level rise and its dynamics and thermodynamics are among the focuses of polar research. Simulation of the ice sheet using numerical modeling constrains a study area’s dynamics and thermodynamics in the absence of observation data and it has become an important means of studying Antarctica. The Marie Byrd Land in West Amtarctica is near the Ford Mountain Range and the Ross Ice Shelf. In this paper, Elmer/Ice is used to simulate Marie Byrd Land’s western region’s ice velocity field, temperature field and pressure field. The study showed that the temperature field at the bottom of the ice sheet in this area was almost uniform, most of the ice bottom reached the pressure melting point, and only a small part of the ice bottom was still below the pressure melting point. There was no obvious difference in the bottom temperature fields among three simulations respectively using different geothermal fluxes (80 mW×m−2, 100 mW×m−2, 120 mW×m−2). The surface ice velocity was also simulated in the x, y, and z directions. The ice sheet’s simulated surface velocities were 0.012 – 744.7 m×a–1. Model results indicate that the vertical direction has the greatest impact on the surface ice velocity; the stress field at the bottom of the ice sheet is roughly inversely proportional to the ice thickness. The z-direction profile from Bedmap 2 was used to analyze the causes of changes in ice flow velocities and ice sheet stress fields, and it is inferred that the existence of deep valleys under the ice may have a strong influence on the ice sheet velocity fields and stress fields. References | Related Articles | Metrics

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Spatial and temporal dynamics of snow pit chemistry in East Antarctica along the Zhongshan Station to Dome A transect Deng Jiayuan, Li Yuansheng, Ma Hongmei, Shi Guitao, Ma Tianming, Lu Siyu 2021, 33 (3):  374-387.  DOI: 10.13679/j.jdyj.20200063 Abstract ( 820 )   PDF (11103KB) ( 453 )   Following completion of the inland survey 35th Chinese National Antarctic Research Expedition, samples from four snow pits along the route from the Zhongshan Station to Dome A section in East Antarctica were analyzed using ion chromatography and major anions and cations concentrations were obtained. Stratigraphic dating (1962–2018) was attempted for a snow pit in Dome A based on seasonal variations of volcanic markers. Temporal and spatial analysis of snow pit ion concentrations show that Cl– and Na+ concentrations in coastal areas were higher because they were affected by marine sources. A gradual increase of the Cl–/Na+ ratio from the coast to inland areas indicates that Cl– had other sources or was affected by volatile HCl deposition. The high concentrations of  SO42– inland may be associated with the low accumulation of snow or the long-distance input of SO42– from mid-and low-latitude regions. Non-sea salt sulfate (nssSO42–) accounted for over 90% of SO42– in snow pits above 2000 m, which indicates that long-distance input of nssSO42– was the main source of SO42– in high altitude areas. NO3– concentrations were complex and showed a large spatial heterogeneity because of accumulation rate, downwind and post-deposition effects. The high NO3– concentration in a snow pit 800 km away from the coast was presumed to be caused by landforms, solar radiation area and 800 km from the coast showed different seasonal characteristics, but there were no obvious seasonal trends in samples from the 520 km or the inland area, which is considered the result of a combination of source, downwind, and post-deposition effects and the accumulation rate. The formation of high salinity “frost flower” and blowing salty snow on sea ice may be a plausible mechanism behind the increase of sea salt ion content in the coastal area. References | Related Articles | Metrics

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Interannual variation of fast ice on Inexpressible Island and analysis of its driving force Sun Xiaoyu, Shen Hui, Li Chunhua, Yu Xupeng, Wang Dali 2021, 33 (3):  388-394.  DOI: 10.13679/j.jdyj.20200055 Abstract ( 743 )   PDF (2240KB) ( 817 )   Long-sequence Landsat remote sensing images were used to extract the fast ice information on Inexpressible Island. Changes in summer fast ice extent were determined for 2008 to 2018. Meteorological data for the same period from Manuela automatic weather station were used to analyze the driving forces of the fast ice changes. The results show that the amount of fast ice reaches its peak in November every year. The fast ice along the coast completely disappears from the end of December to early January and it begins to regenerate at the end of February. The increase in temperature is the main driving force for the reduction of fast ice. A daily average temperature of −10 ±2 ℃ is the critical value for the generation and dissipation of fast ice. When the average daily temperature is stable above −10 ℃, fast ice begins to decrease. Katabatic winds help sea ice drift away but during the period of fast ice reducing katabatic winds are at their weakest for the year, so katabatic winds are only a secondary driving force for the reduction of fast ice. Mastering the causes of interannual variations of fast ice is of great significance for Antarctic scientific research. References | Related Articles | Metrics

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Effects of soluble inorganic nitrogen salts on diversity of rhizosphere soil bacterial community in Ny-Ålesund, Arctic Wang Yu, Han Wenbing, Zhu Qian, Lin Lidong, Wang Nengfei, Zhang Botao 2021, 33 (3):  395-413.  DOI: 10.13679/j.jdyj.20210012 Abstract ( 735 )   PDF (9921KB) ( 332 )   In recent years, global climate change has become increasingly serious, with a wide range of impacts. The polar regions are the earliest to respond to the impacts of climate change. Global climate change has led to the rapid growth of dominant plants such as vascular plants and graminoids in the Arctic. Salix arctica, Bistorta vivipara and Luzula confuse are the three most common dominant species in Ny-Ålesund (Arctic), which are potentially important for the composition and distribution of bacterial communities in the Arctic soil ecosystem. Microorganisms are highly sensitive to environmental changes, but also play a crucial role in the global carbon and nitrogen cycles and polar ecosystems balance. Nitrogen is one of the main nutrient limiting factors for plant growth. In order to study the effect of nitrogen on bacterial community diversity in plant rhizosphere soil in Arctic coastal area, 16S rDNA amplicon sequencing was used to analyze the diversity of bacterial community in three typical types of plant rhizosphere soil and background soil in Ny-Ålesund (Arctic) from 2014 to 2016. The results showed that the soluble inorganic nitrogen (NO2– -N, NO3– -N, NH4+-N) was significantly correlated with the bacterial community in the rhizosphere soil of the three plants (P < 0.05). Nitrosomonadaceae_uncultured and Subgroup 6_norank are the dominant core groups of Salix arctica rhizosphere soil, which have a significant correlation with NO2– -N (P < 0.05). Subgroup 6_norank and JG34-KF-361_norank (Rhizobiales) show a significant correlation with NO3– -N (P < 0.05) in rhizosphere soil of Bistorta vivipara. Acidimicrobiales_norank and Anaerolineaceae_uncultured have a significant correlation with NH4+-N (P < 0.05) in rhizosphere soil of Luzula confuse. Furthermore, concentration of three soluble inorganic nitrogen salts and relative abundance of these core groups show consistent interannual variability. It can be seen that soluble inorganic nitrogen plays an important role in the diversity of bacterial community, especially the change of core bacterial community in the rhizosphere soil of Arctic plants. References | Related Articles | Metrics

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Paths for non-Arctic countries to participate in Arctic scientific cooperation: Taking the Arctic Science Ministerial Conference mechanism as an example Chen Liulin, Liu Jiayue, Wang Wentao, Yu Yong 2021, 33 (3):  414-420.  DOI: 10.13679/j.jdyj.20200049 Abstract ( 815 )   PDF (312KB) ( 896 )   The Arctic Science Ministerial Conference (ASM) is a high-level intergovernmental cooperation and ex-change platform initiated by Arctic countries that comprises major Arctic affairs-related countries and international organizations. Its main goal is to enhance international Arctic scientific cooperation and collaboration. This article combines the latest situation of international Arctic research, analyzes its internal development mechanism and development direction from the perspective of the background and characteristics of development initiated by the ASM Conference, and believes that ASM reflects the United States’ promotion of Arctic scientific research and global leadership. Although the ASM provides equal opportunities for Arctic countries to participate in scientific cooperation and to express their standpoints on the Arctic, its main framework is still deeply influenced and dominated by the Arctic Council. The ASM’s information exchange and supervision mechanism has served as a soft power tool for shaping Arctic research and cooperation among countries. Non-Arctic Countries need to show a more active attitude and measures in scientific and technological strategic integration, scientific and technological project cooperation, and deep involvement in the Arctic observing network and data sharing to enhance the in-fluence of Arctic governance. References | Related Articles | Metrics

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The historical process and experience of China's participation in Antarctic governance: Examples from ATCM and CCAMLR Wang Wanlu 2021, 33 (3):  421-431.  DOI: 10.13679/j.jdyj.20200074 Abstract ( 859 )   PDF (294KB) ( 943 )   Since becoming an Antarctic Treaty Consultative Party in 1985, China has been formally involved in Antarctic governance for 36 years. The Antarctic Treaty Consultative Meeting (ATCM) and the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) are the two most important mechanisms in Antarctic governance, and they are also the main platforms for China to participate in Antarctic governance. Looking back on China's participation in Antarctic governance shows that, after learning and using the rules, China is now trying to create new rules of Antarctic governance. At present, China is faced with challenges such as negative comments and weak institutional discourse power. China should try its best to weaken the influence of the negative comments and reverse containment in the Antarctic in a comprehensive way. China also should pay close attention to small and medium issues, cultivate relevant diplomatic talents and experts, widely participate in various Intersessional Contact Groups and gradually gain institutional discourse power. References | Related Articles | Metrics

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Atlas analysis of 30 years of Arctic environmental research trends using CiteSpace Gu Yue, Lu Zhibo, Yao Junlan 2021, 33 (3):  432-450.  DOI: 10.13679/j.jdyj.20200057 Abstract ( 861 )   PDF (11391KB) ( 563 )   To identify the Arctic environmental research gap between China and other countries, we built an advanced Arctic scientific research framework based on the CiteSpace tool, a bibliometric tool, to conduct a literature review for nearly 30 years of Chinese and international Arctic environmental research from 1990 to 2020. Through co-occurrence, clustering, and co-citation analysis, we found that the development of Arctic environmental research can be divided into slow development, rapid development and stable development stages, and the eight Arctic countries and Germany, Britain and France are the leaders in Arctic environmental research. We also found that Arctic environmental studies are closely related to the disciplines of geology and atmospheric sciences. Sea ice, tundra, permafrost, and snow cover are the most commonly researched environmental media in the Arctic. There is a recent research trend toward examining pollutants such as chlorinated hydrocarbons, ozone, heavy metals, black carbon, as well as persistent organic pollutants. Comparative analysis of the evolution of Chinese and international research found that international Arctic environmental research over 2010—2020 has focused on polar bears, black carbon, perfluorooctane sulfonate, mercury and microplastics. Chinese research on black carbon, microplastics and perfluorooctane sulfonate closely follows the international trend and takes advantage of the height of the Tibetan Plateau to conduct large-scale climate change research; however, Chinese research has obvious deficiencies regarding ecotoxicology. We conclude by proposing that Chinese researchers place greater emphasis on the pollution of environmental media such as sea ice, tundra, permafrost and snow cover to study the occurrence, form, concentration levels and spatial distributions of pollutants. Such research could use techniques from geology, biology, remote sensing and numerical modeling to identify pollution sources, to obtain particle size distribution information and Arctic biological data, and to analyze the biological amplification effect, cumulative effects and potential ecological toxicity of pollutants. This would open up diversified channels for international cooperation and establish active scientific research cooperation in the Arctic environment. It would also further enhance China's long-term monitoring capability in the Arctic region for observing and predicting the temporal trend of Arctic climate change. References | Related Articles | Metrics

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Performance analysis of the first set Sea III gravimeter on Xuelong 2 Chen Qingman, Wang Shuoren, Yuan Dongfang 2021, 33 (3):  451-458.  DOI: 10. 3679/j.jdyj.20200062 Abstract ( 719 )   PDF (1794KB) ( 963 )   The Sea III gravimeter is a new type of pendulum-sliding zero-length spring sea gravity-measuring instrument developed by Micro-g LaCoste manufacturer based on the principles of the LaCoste & Romberg SII gravimeter. In this paper, we have done a performance test of the Sea III gravimeter on Xuelong 2. Firstly, we gave a comprehensive introduction of its working principles, calculate formula and structural characteristics in order to describe the advantage of the Sea III gravimeter. Then the performance of the instrument had been tested both in a static and dynamic way. Xuelong 2 has been designed to sail in a repetitive lane to evaluate its dynamical accuracy. The tests show that the static linear drift rate of the Sea III is about 3.28 × 10−12 m·s2 while the gravimeter records present a clearly characteristic of local earth tide. The dynamic internal compliance accuracy is about 0.23 ×10−5 m·s2, which is far better than the relevant marine survey specification standards. Besides that, the type of Xuelong 2 icebreaker, its equipment layout, gravimetric data processing flow and instrumental performance evaluation are all documented in order to provide a meaningful reference for future users. References | Related Articles | Metrics

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Polar application of the giant piston corer on Xuelong 2 Yuan Dongfang, Wang Shuoren, Chen Qingman, Shen Yue, Liao Zhouxin 2021, 33 (3):  459-468.  DOI: 10.13679/j.jdyj.20200069 Abstract ( 865 )   PDF (2409KB) ( 1009 )   Polar expedition had supplied abundant database for ecology and climatology research, while marine sediment sample is one of the main subject over the Antarctic and Arctic scientific expeditions. Internationally, box-core, grab, and multi-core samplers are widely used to collect pelagic sediments.  However, it should be noted that there is a large gap in the long core sediment sampling equipment around the domestic and foreign countries. The previous Chinese ice-breaker R/V Xuelong does not have the capability to carry a long piston corer and instead has been using a rather short (< 8 m) gravity sampler to collect core sediment. The length of the collected cores is limited to about 4 to 6 m because of the lower recovery rates of gravity corers. On July 11, 2019, R/V Xuelong 2 was officially delivered to the Ministry of Natural Resources and joined the polar expedition sequence of China, which was equipped with a 22-m-long giant piston corer, and start her virgin Antarctic and Arctic voyages later. Two high-quality sediment cores over 18 m long were recovered and sediment recovery was more than 80%. This instrument greatly increases our ability to collect long high-quality sediment cores during polar scientific expeditions. References | Related Articles | Metrics

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Briefing of the 37th Chinese National Antarctic Research Expedition Zhao Jun 2021, 33 (3):  469-471.  Abstract ( 662 )   PDF (223KB) ( 917 )   Related Articles | Metrics

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Chinese Journal of Polar Research indexed in World Journal Clout Index Report (2020 STM) 2021, 33 (3):  472-472.  Abstract ( 496 )   PDF (287KB) ( 274 )   Related Articles | Metrics