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31 December 2021, Volume 33 Issue 4 Previous Issue    Next Issue

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Potential influence of Arctic shipping on passage environments and ecosystems He Jianfeng, Zhang Xia, Lu Zhibo, Wang Juan, Chen Zhiyi 2021, 33 (4):  473-481.  DOI: 10.13679/j.jdyj.20200041 Abstract ( 1267 )   PDF (624KB) ( 2297 )   Following warming and decreasing of pack ice concentrations in the Artic region, the navigability of Arctic passages is increasing. The environment and ecosystem of the Arctic Ocean are fragile, and the influence of increasing Arctic shipping on the local marine environment and ecosystem is of public concern. Fuel leakage, exhaust emission, wastewater discharge, and noise disturbance, are all factors that could affect the environments and ecosystems of these passages. We summarize the situation, discuss the Arctic marine ecosystem and navigation patterns, analyze each factor, and calculate their risk coefficients using the method of Analytical Hierarchy Process. The result shows that exhaust emission, wastewater discharge and fuel leakage are the three most important factors likely to affect the Arctic region related to shipping. Development and application of innovative monitoring technologies will be extremely useful in the future. From the perspective of sustainable Arctic passage utilization, we propose some initiatives, which include studying and developing pollution prevention and control technologies, setting up of ecologically functional zones, constructing an integrated monitoring and assessment system, and strengthening the study of the impacts of fuel leaks. References | Related Articles | Metrics

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The spatial variation of net CO2 fluxes (NEE) and their influence factors in tundra in high Arctic #br# Chen Qingqing, Bao Tao, Zhu Renbin, Xu Hua 2021, 33 (4):  482-496.  DOI: 10.13679/j.jdyj.20200073 Abstract ( 794 )   PDF (886KB) ( 733 )   The release of CO2 from summer ice-free tundra of the high Arctic plays an important role in the global carbon cycle. These net ecosystem exchanges (NEEs) and their influence factors from Seabird Sanctuary Tundra (TSB), Tundra in Non-Seabird Colony (TNS) and Tundra in Transition Zone (TTR) were measured using the closed chamber method during the Fourth Arctic Scientific Exploration (26 July–5 August 2008) in the High Arctic. The spatial variations of NEE show that TSB was a sink for CO2, with an average NEE of (−39.0±6.0) mg·m−2·h−1. Typically, absorption of CO2 in areas with high vegetation cover and strong seabird usage was greater than in areas with lower vegetation cover and seabird usage. In contrast, TNS and TTR were emission sources for CO2, with average NEEs of (12.0±6.3) mg·m−2·h−1 and (40.5±29.3) mg·m−2·h−1, respectively. Highland TTR ((106.4±23.1) mg·m−2·h−1) was the strongest emission source, while peatland TTR [(−58.3±9.5) mg·m−2·h−1] was a strong sink. Spatial variation of NEEs was linked to differences in vegetation cover and hydrological conditions related to seabird activity in all tundra types. Physical and chemical properties of tundra soils also affected NEE values, showing negative correlations with soil moisture (r=−0.44, P=0.003) in TSB and TNS, but a positive correlation with soil temperature (r=0.32, P=0.06) and negative correlations with NH4+-N (P<0.05) and NO3–-N (P<0.05) concentrations in TSB. References | Related Articles | Metrics

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Extraction of Antarctic blue ice based on Landsat-8 imagery Wei Yi, Cheng Xiao, Liu Yan, Hui Fengming, Qu Yutong 2021, 33 (4):  496-507.  DOI: 10.13679/j.jdyj.20210003 Abstract ( 923 )   PDF (17108KB) ( 471 )   Blue ice, a special surface feature of Antarctica, plays an important role in affecting the energy balance at regional to continental scales owing to its low albedo. Its surface ablation leads to the exposure of old ice, making the blue ice an ideal site for paleoclimate study. In addition, blue ice areas are the preferred landing areas for aircrafts because of its high density and hardness. In this study, we propose a rapid, effective, and automatic blue ice extraction method based on a combined index. Using Landsat-8 imagery, we combined the blue ice index and shadow index to derive the Antarctic blue ice distribution. These updated Antarctic blue ice data provide a new resource for studying the Antarctic surface energy balance, paleoclimatology, and selecting blue ice airport sites. We extracted the blue ice locations north of 82.5°S on the Antarctic from 940 scenes of Landsat-8 imagery between 2017 and 2019, while the blue ice locations south of 82.5°S on the Antarctic were extracted from MODIS snow particle size data from 2014. These data were used to map the blue ice distribution over the whole of Antarctica. Results showed that using Landsat-8 imagery, the average accuracy of the blue ice combined index method reached 0.87. The resulting blue ice distribution on the Antarctic is spatially consistent with previous results. The total area of Antarctic blue ice is about 1.7 ×105 km2, 91.4% of which occurs in East Antarctica. Blue ice areas mainly exist near exposed nunataks or mountains,as well as coastal areas. About 60.4% of the Antarctic blue ice occurs within the inland from its coastline to 200 km southward. References | Related Articles | Metrics

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Analysis of temporal and spatial changes in the extent of the Antarctic marginal ice zone from 1979 to 2018 Liu Yue, Pang Xiaoping, Zhao Xi, Huo Rui, Liu Chuang 2021, 33 (4):  508-517.  DOI: 10.13679/j.jdyj.20200071 Abstract ( 1015 )   PDF (2439KB) ( 998 )   The marginal ice zone (MIZ) around Antarctica is an important ocean–air interaction zone and a crucial habitat for marine life. Its annual, seasonal, and regional variations significantly affect the global ocean and atmospheric environments. Based on the sea ice concentration data set of the National Snow and Ice Data Center from 1979 to 2018, the MIZ is defined by a sea ice concentration threshold between 15% and 80%. In this study, we investigated the spatiotemporal variation of the extent of the MIZ, and analyzed its interannual and seasonal changes over the entire Antarctica and its five subregions. Results show that the Antarctic MIZ is not stable, and most of the sea ice in MIZ is less than 20 years. Over the past 40 years, the MIZ extent slightly decreased at a speed of 5.8 ± 2.6×103 km2·a−1 (P < 0.05), although the MIZ average latitude showed no significant trend. Both the MIZ extent and average latitude exhibited stable periodic variations. The MIZ extent is minimal in February, but increases from March to November, decreasing rapidly after reaching its peak in December. The average latitude of the MIZ is northernmost in September and southernmost in February. The MIZ extent in the Weddell Sea is largest among Antarctic sub-regions, where the fluctuations are most obvious and the average latitude is more north. The MIZ extent and average latitude in the five sub-regions are stable during 1979–2018, but the trends of those are the most obvious during 1979—1988 and 1999—2018, respectively. References | Related Articles | Metrics

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Interannual variation characteristics of sea ice in the Weddell Sea Liu Jingzhou, Zhao Liang, Wang Sheng, Bai Yu 2021, 33 (4):  518-528.  DOI: 10.13679/j.jdyj.20200075 Abstract ( 988 )   PDF (8925KB) ( 643 )   Sea ice of the Southern Ocean plays an important role in global climate change, making the Weddell Sea—the biggest bay in the Southern Ocean—a hot spot for studying sea ice change in this area. Based on GLORYS12V1 sea ice density data from 1993 to 2017, this study analyzed the sea ice distribution in the Weddell Sea and its interannual variation. A strong seasonality to the sea ice concentration distribution of the Weddell Sea was found. The distributional differences of the wind field are the main reason that sea ice piles up on one side of Antarctic Peninsula. Under wind effects, the Queen Maud Land’s broad ocean sea ice drifts into the open ocean and melts, producing a spatial distribution with “low west–high east” and “high nearshore–low offshore” sea-ice concentrations. Fluctuations in sea-ice area occur at intervals of 27 months, 35 months, 75 months and 120 months, respectively. Seasonal changes in sea-ice area are not very obvious in spring, fall and winter, but in summer, there is an outstanding increase of around 0.15×105 km2·a−1. The interannual variation of Antarctic sea ice area is mainly affected by thermodynamic factors, including sea surface temperature, as well as temperature and shortwave radiation cycles related to periods of 27 months, 35 months, and 75 months. The general sea ice area has strong negative correlations with temperature and sea surface temperature in spring, summer, and fall, and has a strong negative correlation with solar short-wave radiation over the whole year. References | Related Articles | Metrics

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Analysis of the variation in intensity and source region of the Arctic Transpolar Drift Tian Yin, Bai Xuezhi, Huang Yingqi 2021, 33 (4):  529-544.  DOI: 10.13679/j.jdyj.20210034 Abstract ( 1569 )   PDF (33167KB) ( 819 )   Rapid decline in Arctic sea-ice coverage suggests that the pathway and intensity of the Arctic Transpolar Drift (TPD) have changed evidently. In this study, we calculate sea surface stress in the Arctic by including the effects of both sea ice and surface ocean geostrophic currents to investigate variation in intensity and source region of the TPD. The TPD is stronger in winter than in summer and strongest (weakest) in December (September). During 2003–2014, the annual mean velocity of the TPD increased, and the source area shifted westward from the East Siberian Sea to the Laptev Sea. The main factor affecting interannual variation of the TPD intensity is sea ice coverage; the higher the sea ice coverage, the weaker the TPD. The main factor affecting seasonal variation of the TPD intensity is the seasonal variation of surface winds. In winter (summer), the surface winds and sea surface stresses are strong (weak), as is the TPD intensity. Changes in surface winds and sea ice coverage jointly affect the source region of the TPD. During 2003–2014, the dominant factor controlling the westward movement of the TPD source was the Beaufort High, which moved southwestward from the Beaufort Sea toward the Russian coast,causing the TPD source to move westward. Rapid decline of sea ice coverage also caused westward movement of the TPD source. As sea ice melts, sea surface stresses increase, and the Beaufort Gyre expands from the Canada Basin to the East Siberia Sea, triggering the TPD source to move westward. References | Related Articles | Metrics

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Pathways and properties of Circumpolar Deep Water intrusion on the Amundsen Sea shelf 2021, 33 (4):  545-559.  DOI: 10.13679/j.jdyj.20210004 Abstract ( 967 )   PDF (12586KB) ( 540 )   The relatively warm Circumpolar Deep Water (CDW) has been intruding on the Amundsen Sea continental shelf in recent decades and melting the ice shelves from below, resulting in a continuous ice mass loss in the Amundsen Sea sector of the West Antarctic Ice Shelf. Analysis of the pathways and variations of the CDW intrusion onto the shelf is of great importance to understanding the phenomena of rapid ice shelf thinning and grounding line retreat in this sector. Based on GLORYS12V1 [Global Ocean (1/12)° Physical Reanalysis] data, we calculated the volume and heat transport in the western, central, and eastern channels. We analyzed the relationship between the variations in temperature and salinity of the CDW on the shelf and its flow field. Results showed that the CDW invaded the Dotson–Getz Trough from the western channel, while it invaded the Pine Island Trough from the central and eastern channels. The volume and heat transport of the CDW intruding on the shelf through the western channel showed a weak upward trend over time. The volume and heat transport of the CDW to the Pine Island Trough through the central channel was about twice as much as that through the eastern channel. The temperature of the CDW intrusion into these troughs was controlled by the temperature of the CDW, when it invaded the shelf, and by subsequent processes on the continental shelf. References | Related Articles | Metrics

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The design and realization of a new type of shipborne intelligent atmospheric sampling device Yuan Dongfang, Wang Shuoren, Chen Qingman, Xia Yinyue 2021, 33 (4):  560-567.  DOI: 10.13679/j.jdyj.20200070 Abstract ( 863 )   PDF (1347KB) ( 1494 )   An atmospheric sampling device is the primary equipment required for studying atmospheric pollutants; it collects various types of atmospheric particles, including organic and inorganic pollutants. However, at present, atmospheric samplers are mainly self-developed and modified for land use. Given the particularity of ship environmental conditions, there are certain risks involved in the application of such equipment on board. Therefore, researchers of the Xuelong 2 independently designed and made a new type of marine dual-channel large-flow sampling device. This sampler not only collects large-volume solid phase extraction columns, but also is compatible with other gas particle collections and historical data. It was successfully used during the 36th Chinese National Antarctic Research Expedition and the 11th Chinese National Arctic Research Expedition. References | Related Articles | Metrics

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Analysis on the influence of convective heat transfer of polar ocean engineering equipment plate components Cao Taichun, Wu Gang, Kong Xiangyi, Yu Dongwei, Wu Lin, Zhang Dayong 2021, 33 (4):  568-576.  DOI: 10.13679/j.jdyj.20200080 Abstract ( 858 )   PDF (654KB) ( 772 )   The electric-heat method is the main cold-proof measure for polar ocean engineering equipment, with thermal balance being key to convective heat transfer. Taking an electric heading plate component as a research object, numerical simulations and model tests were carried out to analyze the influence of complex polar environmental factors on the thermal balance of electric heating of marine engineering equipment. Wind speed and temperature were considered as the main environmental parameters in this analysis; wind speed was varied over the range 0–40 m·s–1 and temperature over the range −40–0 °C. Based on FLUENT software simulations and model tests, the convective heat transfer coefficients of the electrical heating plate component under different wind speeds and temperatures were obtained. The results showed that increasing wind speed and decreasing temperature could increase the convective heat transfer coefficient of the plate component. Temperature had little effect on the heat transfer of the plate when the wind speed was stable. In contrast, the convective heat transfer coefficient of the plate increased significantly with increasing wind speed at a given temperature. A mathematical prediction model for the convective heat transfer coefficient of the electrical heating plate component was established based on these experimental data, and the validity of the model was verified by numerical simulation. References | Related Articles | Metrics

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Economic evaluation of various shipping modes via the Northeast Passage Jiang Miaomiao, Hu Maixiu 2021, 33 (4):  577-590.  DOI: 10.13679/j.jdyj.20210016 Abstract ( 851 )   PDF (793KB) ( 1297 )   Based on the monitoring data of sea ice thickness and sea ice concentration of the Northeast Passage from 1991 to 2019, this paper evaluates the economics of shipping through the Northeast Passage under four shipping modes using two evaluation indicators—the shipping cost of a single voyage and annual profit. The results show that not only do different shipping modes have different effects on the shipping economics of the Northeast Passage, but the retreat of the sea ice also has obvious effects. Without taking into account the inter-annual variation of sea ice, the economic benefits of the direct mode are generally higher than that of the transshipment mode, while those of low-ice-class ships are generally better than those of high-ice-class ships. Considering the inter-annual variation of sea ice, and the decline of sea ice, the economics of shipping through the Northeast Passage has significantly improved, especially for low-ice-class ships. References | Related Articles | Metrics

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Advances in subglacial hydrology of Antarctica Zhou Yan, Cui Xiangbin, Dai Zhenxue, Sun Bo, Li Lin 2021, 33 (4):  591-603.  DOI: 10.13679/j.jdyj.20200066 Abstract ( 990 )   PDF (6228KB) ( 1445 )   The extensive development of subglacial lakes and subglacial water systems in Antarctica have potential effect to not only change the basal environment of the ice sheet and affect the bottom sliding process, but also to desalinate the sea water and reduce the deep temperature of the adjacent ocean currents, contributing to one of the uncertainty factors affecting the stability of the ice sheet and its contribution to global sea level and climate change. Therefore, it is of great significance to study the subglacial hydrology and its influence on the dynamics of the Antarctic ice sheet, the evolution of the Antarctic subglacial landforms, and the interaction between the Antarctic ice sheet and the ocean. The subglacial hydrological system involves a complex set of interactions among various components, including ice sheet, subglacial water, subglacial lake, sediment, bedrock, groundwater, flow channel and ocean components. Scientists can use satellite altimeter and other advanced geophysical methods (such as radio echo sounding detection technology, seismic technology, magnetic exploration technology) to observe and study the Antarctic subglacial water system. In addition, numerical simulation supports modeling of the formation, activity and discharge of the subglacial water and the complex processes of land–water–ocean interaction. This paper summarizes the research progress of Antarctic subglacial lake, Antarctic subglacial hydrological system and simulation, and analyzes the interaction among subglacial hydrology, ice shelf and ocean system, and gives the key research direction of Antarctic subglacial hydrological system in the future. References | Related Articles | Metrics

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The deep structure and subglacial processes of the Antarctic ice sheet, and its influence on the ice sheet instability and sea level Tang Xueyuan, Sun Bo, Ma Hongmei, Zhao Liyun, Qiao Gang, Tian Yixiang, Guo Jingxue, Cui Xiangbin, Li Lin 2021, 33 (4):  604-611.  DOI: 10.13679/j.jdyj.20210002 Abstract ( 991 )   PDF (2767KB) ( 1288 )   The effects of ice sheet structure and subglacial processes on ice sheet stability, climate change and global sea-level rise are becoming the frontiers of Antarctic scientific research. However, systematic research remains insufficient on the key physical processes and their effects on the stability of the Antarctic ice sheet at different time-space scales, which has led to wide controversy on the impacts of subglacial processes on global climate change in the international polar scientific community for many years. Based on the aerogeophysical exploration of the Princess Elizabeth Land of the East Antarctica ice sheet, carried out by Chinese National Antarctic Research Expedition since 2015/2016, we summarize the recent research, and clarify the key scientific issues involved in understanding the deep structure and subglacial processes of the Antarctic ice sheet. We expound the obstacles and solutions encountered in the study of the physical mechanisms of the deep structure and processes of the Antarctic ice sheet, by combining intensive observations of the typical areas with the numerical simulations to explore ice sheet stability and its impact on sea level rise. This study contributes to the quantitative estimation of the mass balance of the Antarctic ice sheet and its impact on the future sea level rise. References | Related Articles | Metrics

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Progress of metagenomic analysis of marine viromes in polar regions Zhou Xinhao, Liang Yantao, Andrew McMinn, Wang Min 2021, 33 (4):  612-620.  DOI: 10.13679/j.jdyj.20200077 Abstract ( 1075 )   PDF (320KB) ( 1474 )   The two poles occupy 14% of the surface area of the Earth’s biosphere, and together form the unique frozen cryosphere on Earth. Antarctica is an extremely large continent surrounded by the Southern Ocean, affected by the Antarctic Circumpolar Current. In contrast, the Arctic is composed of the Arctic Ocean surrounded by continents of Europe, Asia, and North America, and many scattered islands. The polar marine biosphere mainly includes two ecosystems: sea water and sea ice; sea ice is a unique ecosystem that exists in the polar regions. The polar oceans, sea ice, subglacial lakes and other environments contain many unknown viruses and their host microbial communities, which are an important driving force of global biogeochemical cycles. This article reviews the progress of viral diversity in the marine environments of the Arctic and Antarctica over the past two decades, which has been mainly unveiled by metagenomic technology. To date, our knowledge of dsDNA viromes has been significantly improved, however, our knowledge of ssDNA and RNA viromes is still very limited in polar marine environments. In general, our understanding of polar marine viruses is still in its infancy, and many novel scientific issues related to polar marine viruses need to be studied in more detail. References | Related Articles | Metrics

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2021 China Polar Science Conference held in Shanghai Shan Yanyan, Jiang Peng 2021, 33 (4):  621-622.  Abstract ( 587 )   PDF (195KB) ( 910 )   References | Related Articles | Metrics