30 December 2021, Volume 32 Issue 4

    

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  Contents of Vol. 32, No 4, 2021

  Editorial Office

  Advances in Polar Science. 2021, 32(4): 0-0.

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  Advances in Polar Science
  Contents Vol. 32 No. 4 December 2021
  Special issue: Sino-Finnish cooperation on cryosphere and climatology in polar and sub-polar regions
  
  Editorial
  An outstanding example of cooperation between Arctic and non-Arctic countries in cryosphere and climate research: Sino-Finnish cooperation for more than 30 years
  Matti LEPPÄRANTA, Timo VIHMA, Bin CHENG & LEI Ruibo
  
  Reviews
  The rise of sea ice research collaboration between China and Finland
  Matti LEPPÄRANTA, WU Huiding, ZHANG Zhanhai, LI Zhijun & Bin CHENG
  Early glaciological and Quaternary Geology cooperation
  Harry ZILLIACUS
  Physics of Arctic landfast sea ice and implications on the cryosphere: an overview
  ZHAI Mengxi, Matti LEPPÄRANTA, Bin CHENG, LEI Ruibo & ZHANG Fanyi
  An overview of Antarctic polynyas: sea ice production, forcing mechanisms, temporal variability and water mass formation
  WEI Zheng, ZHANG Zhaoru, Timo VIHMA, WANG Xiaoqiao & CHEN Yuanjie
  
  Articles
  Observation and modelling of snow and sea ice mass balance and its sensitivity to atmospheric forcing during spring and summer 2007 in the Central Arctic
  Bin CHENG, Timo VIHMA, Timo PALO, Marcel NICOLAUS, Sebastian GERLAND, Laura RONTU, Jari HAAPALA & Donald PEROVICH
  An observational study of precipitation types in the Alaskan Arctic
  YUE Handong, DOU Tingfeng, LI Shutong, LI Chuanjin, DING Minghu & XIAO Cunde
  Variation of Antarctic marginal ice zone extent (1989–2019)
  WANG Miaojiang, LIU Tingting, YANG Zijian, WU Bing & ZHU Xueming
  Modelling on seasonal lake ice evolution in central Asian arid climate zone: a case study
  LU Peng, Bin CHENG, Matti LEPPÄRANTA & LI Zhijun
  The role of lake heat flux in the growth and melting of ice
  Bin CHENG, XIE Fei, LU Peng, HUO Puzhen & Matti LEPPÄRANTA
  Tensile strength of sea ice using splitting tests based on the digital image correlation method
  CHEN Xiaodong, HE Shuaikang, HE Wenquan, WANG Zhaoyu & JI Shunying
  
  Cover picture: snapshots of the long term cooperation between China and Finland
  
  One special issue will be published in 2022
  
  Contents of Volume 32, 2021
  
Reviews
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  An outstanding example of cooperation between Arctic and non-Arctic countries in cryosphere and climate research: Sino-Finnish cooperation for more than 30 years

  Matti LEPPÄRANTA, Timo VIHMA, Bin CHENG, Ruibo LEI

  Advances in Polar Science. 2021, 32(4): 261-263. https://doi.org/10.13679/j.advps.2021.0088

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  The cryosphere is interconnected with other components of the climate system through global exchange of water, energy, and carbon. Long-term sustainable and pragmatic scientific and technological cooperation on the cryosphere and climatology in polar and sub-polar regions between China and Finland began in the 1980s. The fields of bilateral cooperation include joint training of young scientists, joint field observations, climatological and ecological researches of polar and sub-polar sea ice, glaciers and frozen lakes, etc. The year 2020 marked the 70th anniversary of the establishment of diplomatic relations between China and Finland. In order to celebrate the great achievements by Chinese and Finnish scientists in the fields of cryosphere and climate research, the Advances in Polar Science invited scientists from both sides to jointly organize a Special Issue entitled “Sino-Finnish cooperation on cryosphere and climatology in polar and sub-polar regions”. In this Special Issue, we have collected 10 papers, with most papers created jointly by scientists of both sides. The fruitful scientific achievement is strongly benefited from the sustainability of cooperation. Monitoring, research, prediction, mitigation, and adaptation to the climate change in the polar and sub-polar regions will definitively stay in the focus for many decades to come. A new era of Finnish-Chinese scientific collaboration on cryosphere has begun.
  
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  The rise of sea ice research collaboration between China and Finland

  Matti LEPPÄRANTA, Huiding WU, Zhanhai ZHANG, Zhijun LI​, Bin CHENG

  Advances in Polar Science. 2021, 32(4): 264-274. https://doi.org/10.13679/j.advps.2021.0037

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  Collaboration between China and Finland in marine sciences was commenced in winter 1988. The main topic was then short-term sea ice forecasting in the seasonal sea ice zone (SSIZ), particularly in the Bohai Sea in China and the Baltic Sea in Finland. The sea ice in SSIZ is thin and highly dynamic so that ice conditions may change rapidly. While the length scales of the Baltic Sea and the Bohai Sea are similar, the main difference between them is that the former is brackish and non-tidal while the latter is oceanic for the salinity and possesses a large tidal amplitude. The Bohai Sea is located at latitudes 37^°N–41^°N, and the Baltic Sea is located at latitudes 55^°N–66^°N. However, the same sea ice model is applicable for both. The main application field of sea ice forecasting was winter shipping in Finland and oil drilling in China. The collaboration was successful and in late 1990s the research was expanded to polar seas, lakes, and to climate change applications.
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  Early glaciological and Quaternary Geology cooperation

  Harry ZILLIACUS

  Advances in Polar Science. 2021, 32(4): 275-280. https://doi.org/10.13679/j.advps.2021.0032

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  The article depicts the author's experiences of Glaciology and Quaternary Geology research between Finland and the People's Republic of China. The focus is on a visit to a glaciological station in Tianshan in 1988. The climate is continental displaying warming-up and increased precipitation since the end of the 1980's. The data collected here is of utmost importance when analysing the future development of the glaciers. Some associations to the historic Silk Roads are made having implications on the Belt and Road strategy launched by the Chinese. As to problems of sea and lake ice, Finland and the P. R. China have found issues of mutual interest resulting in continuing cooperation in the Arctic and in ice-covered areas of China. New forms of bilateral collaboration such as university education and training have evolved encompassing coming generations.
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  Physics of Arctic landfast sea ice and implications on the cryosphere: an overview

  Mengxi ZHAI​, Matti LEPPÄRANTA, Bin CHENG, Ruibo LEI​, Fanyi ZHANG​

  Advances in Polar Science. 2021, 32(4): 281-294. https://doi.org/10.13679/j.advps.2021.0040

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  Landfast sea ice (LFSI) is a critical component of the Arctic sea ice cover, and is changing as a result of Arctic amplification of climate change. Located in coastal areas, LFSI is of great significance to the physical and ecological systems of the Arctic shelf and in local indigenous communities. We present an overview of the physics of Arctic LFSI and the associated implications on the cryosphere. LFSI is kept in place by four anchoring mechanisms. The evolution of LFSI is mostly determined by thermodynamic processes, and can therefore be used as an indicator of local climate change. We also present the dynamic processes that are active prior to the formation of LFSI, and those that are involved in LFSI freeze-up and breakup. Season length, thickness and extent of Arctic LFSI are decreasing and showing different trends in different seas, and therefore, causing environmental and climatic impacts. An improved coordination of Arctic LFSI observation is needed with a unified and systematic observation network supported by cooperation between scientists and indigenous communities, as well as a better application of remote sensing data to acquire detailed LFSI cryosphere physical parameters, hence revolving both its annual cycle and long-term changes. Integrated investigations combining in situ measurements, satellite remote sensing and numerical modeling are needed to improve our understanding of the physical mechanisms of LFSI seasonal changes and their impacts on the environment and climate.
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  An overview of Antarctic polynyas: sea ice production, forcing mechanisms, temporal variability and water mass formation

  Zheng WEI, Zhaoru ZHANG, Timo VIHMA, Xiaoqiao WANG, Yuanjie CHEN

  Advances in Polar Science. 2021, 32(4): 295-311. https://doi.org/10.13679/j.advps.2021.0026

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  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.
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  Observation and modelling of snow and sea ice mass balance and its sensitivity to atmospheric forcing during spring and summer 2007 in the Central Arctic

  Bin CHENG, Timo VIHMA, Timo PALO, Marcel NICOLAUS, Sebastian GERLAND, Laura RONTU, Jari HAAPALA, Donald PEROVICH

  Advances in Polar Science. 2021, 32(4): 312-326. https://doi.org/10.13679/j.advps.2021.0047

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  Snow depth and sea ice thickness were observed applying an ice mass balance buoy (IMB) in the drifting ice station Tara during the International Polar Year in 2007. Detailed in situ observations on meteorological variables and surface fluxes were taken during May to August. For this study, the operational analyses and short-term forecasts from two numerical weather prediction (NWP) models (ECMWF and HIRLAM) were extracted for the Tara drift trajectory. We compared the IMB, meteorological and surface flux observations against the NWP products, also applying a one-dimensional thermodynamic sea ice model (HIGHTSI) to calculate the snow and ice mass balance and its sensitivity to atmospheric forcing. The modelled snow depth time series, controlled by NWP-based precipitation, was in line with the observed one. HIGHTSI reproduced well the snowmelt onset, the progress of the melt, and the first date of snow-free conditions. HIGHTSI performed well also in the late August freezing season. Challenges remain to model the “false bottom” observed during the melting season. The evolution of the vertical temperature profiles in snow and ice was better simulated when the model was forced by in situ observations instead of NWP results. During the melting period, the nonlinear ice temperature profile was successfully modelled with both forcing options. During spring and the melting season, total sea ice mass balance was most sensitive to uncertainties in NWP results for the downward longwave radiation, followed by the downward shortwave radiation, air temperature, and wind speed.
Articles
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  An observational study of precipitation types in the Alaskan Arctic

  Handong YUE, Tingfeng DOU​, Shutong LI​, Chuanjin LI​, Minghu DING​, Cunde XIAO​

  Advances in Polar Science. 2021, 32(4): 327-340. https://doi.org/10.13679/j.advps.2021.0027

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  The effects of various precipitation types, such as snow, rain, sleet, hail and freezing rain, on regional hydrology, ecology, snow and ice surfaces differ significantly. Due to limited observations, however, few studies into precipitation types have been conducted in the Arctic. Based on the high-resolution precipitation records from an OTT Parsivel² disdrometer in Utqiaġvik, Alaska, this study analysed variations in precipitation types in the Alaskan Arctic from 15 May to 16 October, 2019. Results show that rain and snow were the dominant precipitation types during the measurement period, accounting for 92% of the total precipitation. In addition, freezing rain, sleet, and hail were also observed (2, 4 and 11 times, respectively), accounting for the rest part of the total precipitation. The records from a neighbouring U.S. Climate Reference Network (USCRN) station equipped with T-200B rain gauges support the results of disdrometer. Further analysis revealed that Global Precipitation Measurement (GPM) satellite data could well characterise the observed precipitation changes in Utqiaġvik. Combined with satellite data and station observations, the spatiotemporal variations in precipitation were verified in various reanalysis datasets, and the results indicated that ECMWF Reanalysis v5 (ERA5) could better describe the observed precipitation time series in Utqiaġvik and the spatial distribution of data in the Alaskan Arctic. Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) overestimated the amount and frequency of precipitation. Japanese 55-year Reanalysis (JRA-55) could better simulate heavy precipitation events and the spatial distribution of the precipitation phase, but it overestimated summer snowfall.
  
  
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  Variation of Antarctic marginal ice zone extent (1989–2019)

  Miaojiang WANG, Tingting LIU​, Zijian YANG, Bing WU, Xueming ZHU​

  Advances in Polar Science. 2021, 32(4): 341-355. https://doi.org/10.13679/j.advps.2021.0042

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  The Antarctic marginal ice zone (MIZ) is the transition region between open water and consolidated pack ice, which is defined as an area with 15%–80% sea ice concentration. The MIZ represents the outer circle of Antarctic sea ice and the biological activity circle of Antarctic organisms, which provides a direct indication of the extent of Antarctic sea ice. In this study, the joint total variation and nonnegative constrained least square algorithm are applied to retrieve the Antarctic MIZ extent based on passive microwave data sets from 1989 to 2019. The spatial and temporal variations of the Antarctic MIZ extent and five regions are analyzed. The results show that the Antarctic MIZ extent follows a strong monthly variation pattern, decreasing from November to February and increasing from March to October. The annual MIZ extent is largest in the Weddell Sea and smallest in the Western Pacific Ocean. The edge of the sea ice begins to form a closed ring in May, which eventually closes near the Antarctic Peninsula. The ring width variation is large in summer, but generally stabilizes between 350 and 370 km in winter. The average latitude of the Antarctic MIZ is relatively stable in summer, but changes substantially in winter with a difference of approximately 3°. In October, the lowest mean latitude of the MIZ can reach 64.35°S. The sea surface pressure, 2-m temperature, and 10-m wind speed are negatively correlated with the MIZ extent variation, among which the second-order partial correlation coefficient of the sea surface pressure and MIZ extent is −0.8773 in the Western Pacific Ocean.
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  Modelling on seasonal lake ice evolution in central Asian arid climate zone: a case study

  Peng LU, Bin CHENG, Matti LEPPÄRANTA, Zhijun LI

  Advances in Polar Science. 2021, 32(4): 356-363. https://doi.org/10.13679/j.advps.2021.0025

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  The seasonal cycle of ice thickness and temperature in Lake Wuliangsuhai, a typical shallow lake in the central Asian arid climate zone, was simulated using the HIGHTSI model and the MERRA-2 data as the meteorological forcing. The average ice growth rate was 0.64 cm•d⁻¹ and −1.65 cm•d⁻¹ for the growth and melting stage of the ice cover, respectively. The ice thickness agreed well with the field observations conducted in winter 2017, with a correlation coefficient of 0.97. The ice temperature field also agreed with observations in both daily variations and the vertical profile, and a better agreement in the daily amplitude and profile shape of ice temperature could be achieved if field data on physical properties of snow cover and melting ice were available. This study proved the feasibility of both the HIGHTSI model and the MERRA-2 data for modeling the ice cover evolution in Lake Wuliangsuhai, providing a basis for a deep insight into the difference of lake ice evolution between central Asian arid climate zone and polar/sub-polar regions.
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  The role of lake heat flux in the growth and melting of ice

  Bin CHENG, Fei XIE, Peng LU, Puzhen HUO, Matti LEPPÄRANTA

  Advances in Polar Science. 2021, 32(4): 364-373. https://doi.org/10.13679/j.advps.2021.0051

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  For shallow lakes, ice mass balance is largely dominated by thermodynamic processes. The heat flux from lake water plays a critical role for ice growth and melting. In this study, we applied a numerical thermodynamic lake model to investigate the sensitivity of the lake ice mass balance to the lake heat flux during the growth and melting periods. Several groups of modelling experiments forced by simplified climatological weather data have been carried out. Two sites, Lake Wuliangsuhai in Inner Mongolia, China’s arid region and Lake Orajärvi in snowy Finnish Lapland, were investigated. Lake heat flux affects inversely proportional maximum ice thickness followed by ice break-up date. The solar radiation and surface albedo complicate the effect of lake heat flux on lake ice mass balance during melting season. With heavy snowfall, the increase of lake heat flux adds on the formation of granular ice but reduces the formation of columnar ice. Under climatological weather conditions, the ice cover winter seasonal mean lake heat flux were 14 W•m⁻² and 4 W•m⁻² in Lake Wuliangsuhai and Lake Orajärvi, respectively.
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  Tensile strength of sea ice using splitting tests based on the digital image correlation method

  ​Xiaodong CHEN, Shuaikang HE, Wenquan HE, Zhaoyu WANG, Shunying JI

  Advances in Polar Science. 2021, 32(4): 374-381. https://doi.org/10.13679/j.advps.2021.0043

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  The splitting test is a competitive alternative method to study the tensile strength of sea ice owing to its suitability for sampling. However, the approach was questioned to the neglect of local plastic deformation during the tests. In this study, splitting tests were performed on sea ice, with 32 samples subjected to the regular procedure and 8 samples subjected to the digital image correlation method. The salinity, density, and temperature were measured to determine the total porosity. With the advantage of the digital image correlation method, the full-field deformation of the ice samples could be determined. In the loading direction, the samples mainly deformed at the ice–platen contact area. In the direction vertical to the loading, deformation appears along the central line where the splitting crack occurs. Based on the distribution of the sample deformation, a modified solution was derived to calculate the tensile strength with the maximum load. Based on the modified solution, the tensile strength was further calculated together with the splitting test results. The results show that the tensile strength has a negative correlation with the total porosity, which agrees with previous studies based on uniaxial tension tests.
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  Cover picture: snapshots of the long term cooperation between China and Finland

  Bin CHENG, Ruibo LEI

  Advances in Polar Science. 2021, 32(4): 382-382. https://doi.org/10.13679/j.advps.2021.0089

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  The four historic pictures see the story of the long term cooperation between China and Finland. Some representative results are presented in this special issue.
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  One special issue will be published in 2022

  Editorial Office

  Advances in Polar Science. 2021, 32(4): 383-383.

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  The special issue entitled “Emerging Technologies and Their Application in the Polar Regions” will be published in December 2022 as general issue (Vol. 33, No. 4), the theme of which focuses on autonomous profiling floats; under-ice gliders (AUV and ROV); deep-ocean rovers; automatic weather stations; unmanned aerial vehicles; robotic camera systems; in situ sensors and methods for collecting autonomous observations. We are so honored to invite Prof. Pavel G. Talalay from Institute of Polar Science and Engineering, Jilin University, China, as lead Guest Editor to organize this special issue. We sincerely invite you to contribute to this special issue or other general issues in 2022 and beyond. Submissions deadline for this issue is May 31, 2022. Submission website: https://mc03.manuscriptcentral.com/apsci
Contents
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  Contents of Volume 32, 2021

  Editorial Office

  Advances in Polar Science. 2021, 32(4): 384-386.

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  CONTENTS (Volume 32, 2021) Advances in Polar Science
  
  Issue 32 No 1
  Multi-sensor data merging of sea ice concentration and thickness
  Keguang WANG, Thomas LAVERGNE & Frode DINESSEN
  Editorial Note
  Spatial variability in carbon dioxide exchange processes within wet sedge meadows in the Canadian High Arctic
  Claire M. WRIGHT, Amy C. BLASER, Paul M. TREITZ & Neal A. SCOTT
  Complete genome analysis of bacteriochlorophyll a-containing Roseicitreum antarcticum ZS2-28T reveals its adaptation to Antarctic intertidal environment
  ZENG Yinxin, YU Yong, LI Huirong, LUO Wei & DING Haitao
  Biomarker records of D5-6 columns in the eastern Antarctic Peninsula waters: responses of planktonic communities and bio-pump structures to sea ice global warming in the past centenary
  YANG Dan, ZHANG Haisheng, HAN Zhengbing, HAN Xibin, ZHANG Yicheng, CHEN Wensheng, LIU Qian, PAN Jianming, FAN Gaojing, LE Fengfeng, LU Bing & HUANG Jing
  Seabird and marine mammal at-sea distribution in the western Bering Sea and along the eastern Kamtchatka Peninsula
  Claude R. JOIRIS
  Assessment on India’s involvement and capacity-building in Arctic Science
  Nikhil PAREEK
  Leveraging the UAV to support Chinese Antarctic expeditions: a new perspective
  LI Teng, ZHANG Baogang, CHENG Xiao, HUI Fengming & LI Yuansheng
  
  Issue 32 No 2
  Editorial
  Towards an integrated study of subglacial conditions in Princess Elizabeth Land, East Antarctica
  TANG Xueyuan & SUN Bo
  Characteristics and spatial distribution of strong warming events in the central Arctic (2000–2019)
  ZHANG Zelu, ZHAO Jinping & BIAN Lingen
  Factors contributing to rapid decline of Arctic sea ice in autumn
  LI Shuyao, CUI Hongyan, XU Junli, GONG Xiang, QIAO Fangli, YANG Yanzhao, WANG Ping, HAN Yuqun & SHAN Feng
  Retrievals of Arctic sea ice melt pond depth and underlying ice thickness using optical data
  ZHANG hang, YU Miao, LU Peng, ZHOU Jiaru & LI Zhijun
  Ocean stratification and sea-ice cover in Barents and Kara seas modulate sea-air methane flux: satellite data
  Leonid YURGANOV, Dustin CARROLL, Andrey PNYUSHKOV, Igor POLYAKOV & Hong ZHANG
  A case study based on ground observations of the conjugate ionospheric response to interplanetary shock in polar regions
  HE Fang, HU Zejun, HU Hongqiao, HUANG Dehong & YU Yao
  Traditional Arctic native fish storage methods and their role in the sustainable development of the Arctic
  LUO Ying, Andrew Alexandrovich LOBANOV, HUI Fengming, Sergei Vasilevich ANDRONOV, Lidiya Petrovna LOBANOVA, Elena Nikolaevna BOGDANOVA, Irina Alexandrovna GRISHECHKINA, Andrei Ivanovich POPOV & Roman Yurievich FEDOROV
  
  Issue 32 No 3
  Application of unmanned underwater vehicles in polar research
  ZENG Junbao, LI Shuo & LIU Ya
  Utilization of clean energy and future trend of Antarctic research stations
  LI Zhao, LÜ Dongxiang, SUN Zilu & LI Chuan
  Marine biogenic aerosols and their effects on aerosol-cloud interactions over the Southern Ocean: a review
  XU Yifan, XU Guojie, CHEN Liqi & ZHANG Miming
  The marine environmental evolution in the northern Norwegian Sea revealed by foraminifera during the last 60 ka
  WANG Weiguo, ZHAO Mengwei, YANG Jichao, XIAO Wenshen, WANG Haoyin & LIU Yang
  Characteristics of hydrogen/oxygen isotopes in water masses and implications for spatial distribution of freshwater in the Amundsen Sea, Southern Ocean
  SHAO Hebin, HE Jianfeng, LUO Guangfu, LAN Musheng, YU Lejiang, GUO Guijun & LIAN Ergang
  Different physiopsychological changes between AMS-susceptible and AMS-resistant pre-selected Antarctic expeditioners in Tibet
  WU Xiaopei, LIU Shiying, WANG Xi, WANG Jianan, QIN Pengrui & XU Chengli
  An introduction to the riometer system deployed at China-Iceland joint Arctic observatory and its beam-forming correction method based on the preliminary data
  HE Fang, HU Zejun, HU Hongqiao, HUANG Dehong & YU Yao
  
  Issue 32 No 4
  Editorial — An outstanding example of cooperation between Arctic and non-Arctic countries in cryosphere and climate research: Sino-Finnish cooperation for more than 30 years
  Matti LEPPÄRANTA, Timo VIHMA, Bin CHENG & LEI Ruibo
  The rise of sea ice research collaboration between China and Finland
  Matti LEPPÄRANTA, WU Huiding, ZHANG Zhanhai, LI Zhijun & Bin CHENG
  Early glaciological and Quaternary Geology cooperation
  Harry ZILLIACUS
  Physics of Arctic landfast sea ice and implications on the cryosphere: an overview
  ZHAI Mengxi, Matti LEPPÄRANTA, Bin CHENG, LEI Ruibo & ZHANG Fanyi
  An overview of Antarctic polynyas: sea ice production, forcing mechanisms, temporal variability and water mass formation
  WEI Zheng, ZHANG Zhaoru, Timo VIHMA, WANG Xiaoqiao & CHEN Yuanjie
  Observation and modelling of snow and sea ice mass balance and its sensitivity to atmospheric forcing during spring and summer 2007 in the Central Arctic
  Bin CHENG, Timo VIHMA, Timo PALO, Marcel NICOLAUS, Sebastian GERLAND, Laura RONTU, Jari HAAPALA & Donald PEROVICH
  An observational study of precipitation types in the Alaskan Arctic
  YUE Handong, DOU Tingfeng, LI Shutong, LI Chuanjin, DING Minghu & XIAO Cunde
  Variation of Antarctic marginal ice zone extent (1989–2019)
  WANG Miaojiang, LIU Tingting, YANG Zijian, WU Bing & ZHU Xueming
  Modelling on seasonal lake ice evolution in central Asian arid climate zone: a case study
  LU Peng, Bin CHENG, Matti LEPPÄRANTA & LI Zhijun
  The role of lake heat flux in the growth and melting of ice
  Bin CHENG, XIE Fei, LU Peng, HUO Puzhen & Matti LEPPÄRANTA
  Tensile strength of sea ice using splitting tests based on the digital image correlation method
  CHEN Xiaodong, HE Shuaikang, HE Wenquan, WANG Zhaoyu & JI Shunying
  Cover picture: snapshots of the long term cooperation between China and Finland
  One special issue will be published in 2022
  
  Contents of Volume 32, 2021