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Microscopic analysis on eukaryotic algae and cyanobacteria in nine seasonal lakes and ponds in Vestfjella,Dronning Maud Land,Antarctica

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Advances in Polar Science 2024年第2期35卷 206-218页

作者： Lauri ARVOLA matti leppäranta LI Zhijun Lammi Biological Station University of HelsinkiLammi FI-16900Finland Department of Physics University of HelsinkiHelsinki FI-00014Finland State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116023China

Antarctic continental lakes and ponds are among the most impoverished aquatic environments on earth but many of them support flourishing populations of cyanobacteria,eukaryotic algae,protozoans,and some multicellular *** this study,we present results of a microscopic analysis of cyanobacteria and eukaryotic algae from nine diverse types of Antarctic continental water bodies during one austral *** results supplement and enlarge our previous studies on the limnological characteristics of the epiglacial and supraglacial lakes and ponds in Dronning Maud Land,an area that has received little attention from *** taxon with highest frequency among the samples(n=79)was Mesotaenium ***,a eukaryotic Zygnematophyceae,which occurred in 82%of the samples with a maximum cell density of 68 cells·mL^(-1).The taxa with second and third highest frequency were the prokaryotes Gloeocapsopsis(60%)and Leptolyngbya(41%),followed by Chlamydomonas(34%)and Cyanothece(29%).The number of taxa varied between 7-21 among the lakes and ponds,being highest in a supraglacial lake,and lowest in an epiglacial *** results did not reveal any obvious correlation between the abundance of any taxa and the water chemistry,but water bodies with inorganic sediments had higher cell densities and biomasses than those without *** suggests the importance of sediment in supporting biological diversity in these ultraoligotrophic lakes and ponds.

关键词： Antarctic continental lakes Antarctic continental ponds cyanobacteria algae protozoa rotifers tardigrada

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A lake ice phenology dataset for the Northern Hemisphere based on passive microwave remote sensing

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Big Earth Data 2022年第4期6卷 401-419页

作者： Xingxing Wang Yubao Qiu Yixiao Zhang Juha Lemmetyinen Bin Cheng Wenshan Liang matti leppäranta College of Urban and Environment Sciences Northwest UniversityXi’anChina Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijingChina International Research Center of Big Data for Sustainable Development Goals BeijingChina FMI-AIR Joint Research Center for Arctic Observations Finnish Meteorological Institute and Aerospace Information Research InstituteChinese Academy of SciencesSodankyläFinland Arctic Space Center Finnish Meteorological InstituteHelsinkiFinland Finnish Meteorological Institute HelsinkiFinland Institute of Atmospheric and Earth Sciences University of HelsinkiHelsinkiFinland

Lake ice phenology(LIP)is an essential indicator of climate change and helps with understanding of the regional characteristics of climate change *** observation records and remote sensing retrieval products of lake ice phenology are abundant for Europe,North America,and the Tibetan Plateau,but there is a lack of data for inner *** this work,enhanced-resolution passive microwave satellite data(PMW)were used to investigate the Northern Hemisphere Lake Ice Phenology(PMW LIP).The Freeze Onset(FO),Complete Ice Cover(CIC),Melt Onset(MO),and Complete Ice Free(CIF)dates were derived for 753 lakes,including 409 lakes for which ice phenology retrievals were available for the period 1978 to 2020 and 344 lakes for which these were available for 2002 to *** of the PMW LIP using ground records gave correlation coefficients of 0.93 and 0.84 for CIC and CIF,respectively,and the corresponding values of the RMSE were 11.84 and 10.07 *** lake ice phenology in this dataset was significantly correlated(P<0.001)with that obtained from Moderate Resolution Imaging Spectroradiometer(MODIS)data-the average correlation coefficient was 0.90 and the average RMSE was 7.87 *** minimum RMSE was 4.39 days for *** PMW is not affected by the weather or the amount of sunlight and thus provides more reliable data about the freezing and thawing process information than MODIS *** PMW LIP dataset pro-vides the basic freeze-thaw data that is required for research into lake ice and the impact of climate change in the cold regions of the Northern *** dataset is available at http://***/10.11922/sciencedb.j00076.00081.

关键词： Lake ice phenology dataset Northern Hemisphere passive microwave remote sensing

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Modelling on seasonal lake ice evolution in central Asian arid climate zone: a case study

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Advances in Polar Science 2021年第4期32卷 356-363页

作者： LU Peng Bin CHENG matti leppäranta LI Zhijun State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116081China Finnish Meteorological Institute Helsinki Fi-00101Finland University of Helsinki Helsinki Fi-00014Finland

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 *** 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,*** ice thickness agreed well with the field observations conducted in winter 2017,with a correlation coefficient of *** 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 andmelting ice were *** 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.

关键词： lake ice HIGHTSI model ice thickness ice temperature

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Comparisons of passive microwave remote sensing sea ice concentrations with ship-based visual observations during the CHINARE Arctic summer cruises of 2010–2018

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Acta Oceanologica Sinica 2020年第9期39卷 38-49页

作者： Yuanren Xiu Zhijun Li Ruibo Lei Qingkai Wang Peng Lu matti leppäranta State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China MNR Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China Institute of Atmospheric and Earth Sciences University of HelsinkiHelsinki 00014Finland

In order to apply satellite data to guiding navigation in the Arctic more effectively,the sea ice concentrations(SIC)derived from passive microwave(PM)products were compared with ship-based visual observations(OBS)collected during the Chinese National Arctic Research Expeditions(CHINARE).A total of 3667 observations were collected in the Arctic summers of 2010,2012,2014,2016,and *** SIC were derived from the NASA-Team(NT),Bootstrap(BT)and Climate Data Record(CDR)algorithms based on the SSMIS sensor,as well as the BT,enhanced NASA-Team(NT2)and ARTIST Sea Ice(ASI)algorithms based on AMSR-E/AMSR-2 *** daily arithmetic average of PM SIC values and the daily weighted average of OBS SIC values were used for the *** correlation coefficients(CC),biases and root mean square deviations(RMSD)between PM SIC and OBS SIC were compared in terms of the overall trend,and under mild/normal/severe ice *** the OBS data,the influences of floe size and ice thickness on the SIC retrieval of different PM products were evaluated by calculating the daily weighted average of floe size code and ice *** results show that CC values range from 0.89(AMSR-E/AMSR-2 NT2)to 0.95(SSMIS NT),biases range from−3.96%(SSMIS NT)to 12.05%(AMSR-E/AMSR-2 NT2),and RMSD values range from 10.81%(SSMIS NT)to 20.15%(AMSR-E/AMSR-2 NT2).Floe size has a significant influence on the SIC retrievals of the PM products,and most of the PM products tend to underestimate SIC under smaller floe size conditions and overestimate SIC under larger floe size *** thickness thicker than 30 cm does not have a significant influence on the SIC retrieval of PM ***,the best(worst)agreement occurs between OBS SIC and SSMIS NT(AMSR-E/AMSR-2 NT2)SIC in the Arctic summer.

关键词： sea ice concentration passive microwave remote sensing ship-based visual observations Arctic navigation summer

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Physics of Arctic landfast sea ice and implications on the cryosphere: an overview

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Advances in Polar Science 2021年第4期32卷 281-294页

作者： ZHAI Mengxi matti leppäranta Bin CHENG LEI Ruibo ZHANG Fanyi Key Laboratory of Polar Science MNRPolar Research Institute of ChinaShanghai 200136China University of Helsinki Helsinki Fi-00014Finland Finnish Meteorological Institute Helsinki Fi-00101Finland

Landfast sea ice(LFSI)is a criticalcomponent of the Arctic sea ice cover,and is changing as a result of Arctic amplification of climate *** in coastal areas,LFSI is of great significance to the physical and ecological systems of the Arctic shelf and in local indigenous *** present an overview of the physics of Arctic LFSI and the associated implications on the *** is kept in place by four *** evolution of LFSI is mostly determined by thermodynamic processes,and can therefore be usedas an indicator of local climate *** also present the dynamic processes that are active prior to the formation of LFSI,and those that are involved in LFSI freeze-up and *** length,thickness and extent of Arctic LFSI are decreasing andshowing different trends in different seas,and therefore,causing environmental and climatic *** 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 *** 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.

关键词： landfast sea ice Arctic Ocean remote sensing mass balance

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The role of lake heat flux in the growth and melting of ice

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Advances in Polar Science 2021年第4期32卷 364-373页

作者： Bin CHENG XIE Fei LU Peng HUO Puzhen matti leppäranta Finnish Meteorological Institute Helsinki Fi-00101Finland State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116081China University of Helsinki Helsinki Fi-00014Finland

For shallow lakes,ice mass balance is largely dominated by thermodynamic *** heat flux from lake water plays a critical role for ice growth and *** 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 *** groups of modelling experiments forced by simplified climatological weather data have been carried *** sites,Lake Wuliangsuhai inInner Mongolia,China’s arid region and Lake Orajärvi in snowy Finnish Lapland,were *** heat flux affects inversely proportional maximum ice thickness followed by ice break-up *** solar radiation and surface albedo complicate the effect of lake heat flux on lake ice mass balance during melting *** heavy snowfall,the increase of lake heat flux adds on the formation of granular ice but reduces the formation of columnar *** climatological weather conditions,theice cover winter seasonal mean lake heat flux were 14 W·m^(−2) and 4 W·m^(−2) in Lake Wuliangsuhai and Lake Orajärvi,respectively.

关键词： shallow lakes lake ice heat flux numerical modelling

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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

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Advances in Polar Science 2021年第4期32卷 261-263页

作者： matti leppäranta Timo VIHMA Bin CHENG LEI Ruibo University of Helsinki Helsinki Fi-00014Finland Finnish Meteorological Institute Helsinki Fi-00101Finland Key Laboratory of Polar Science MNRPolar Research Institute of ChinaShanghai 200136China

The cryosphere is interconnected with other components of the climate system through global exchange of water,energy,and ***-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 *** 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,*** year 2020 marked the 70th anniversary of the establishment of diplomatic relations between China and *** order to celebrate the great achievements by Chinese and Finnish scientists in the fieldsof 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 *** fruitful scientific achievement is strongly benefited from the sustainability of ***,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.

关键词： China Finland international cooperation cryosphere climate polar region sub-polar region

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The rise of sea ice research collaboration between China and Finland

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Advances in Polar Science 2021年第4期32卷 264-274页

作者： matti leppäranta WU Huiding ZHANG Zhanhai LI Zhijun Bin CHENG University of Helsinki Helsinki Fi-00014Finland National Marine Environmental Forecasting Center Beijing 100081China Ministry of Natural Resources(MNR) Beijing 100812China State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116081China Finnish Meteorological Institute Helsinki Fi-00101Finland

Collaboration between China and Finland in marine sciences was commenced in winter *** 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 *** sea ice in SSIZ is thin and highly dynamic so that ice conditions may change *** 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 *** Bohai Sea is located at latitudes 37°N-41°N,and the Baltic Sea is located at latitudes 55°N-66°***,the same sea ice model is applicable for *** main application field of sea ice forecasting was winter shipping in Finland and oil drilling in *** collaboration was successful and in late 1990s the research was expanded to polar seas,lakes,and to climate change applications.

关键词： sea ice Baltic Sea Bohai Sea dynamics thermodynamics ice engineering

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TanDEM-X multiparametric data features in sea ice classification over the Baltic sea

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Geo-Spatial Information Science 2021年第2期24卷 313-332,I0009页

作者： Marjan Marbouti Oleg Antropov Jaan Praks Patrick B.Eriksson Vahid Arabzadeh Eero Rinne matti leppärant Institute for Atmospheric and Earth System Research/Physics Faculty of ScienceUniversity of HelsinkiHelsinkiFinland VTT Technical Research Centre of Finland EspooFinland Aalto University Department of Electronics and NanoengineeringEspooFinland Finnish Meteorological Institute HelsinkiFinland Aalto University Department of Applied PhysicsNew Energy Technologies GroupEspooFinland

In this study,we assess the potential of X-band Interferometric Synthetic Aperture Radar imagery for automated classification of sea ice over the Baltic Sea.A bistatic SAR scene acquired by the TanDEM-X mission over the Bothnian Bay in March of 2012 was used in the *** intensity,interferometric coherence magnitude,and interferometric phase have been used as informative features in several classification *** combinations of classification features were evaluated using Maximum likelihood(ML),Random Forests(RF)and Support Vector Machine(SVM)classifiers to achieve the best possible discrimination between open water and several sea ice types(undeformed ice,ridged ice,moderately deformed ice,brash ice,thick level ice,and new ice).Adding interferometric phase and coherence-magnitude to backscatter-intensity resulted in improved overall classification per-formance compared to using only *** RF algorithm appeared to be slightly superior to SVM and ML due to higher overall accuracies,however,at the expense of somewhat longer processing *** best overall accuracy(OA)for three methodologies were achieved using combination of all tested features were 71.56,72.93,and 72.91%for ML,RF and SVM classifiers,*** to OAs of 62.28,66.51,and 63.05%using only backscatter intensity,this indicates strong benefit of SAR interferometry in discriminating different types of sea *** contrast to several earlier studies,we were particularly able to successfully discriminate open water and new ice classes.

关键词： Sea ice classification Random Forests(RF) Maximum Likelihood(ML) Support Vector Machine(SVM) backscatter coherence sar interferometry Synthetic Aperture Radar(SAR)

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Spatial and temporal evolution of landfast ice near Zhongshan Station, East Antarctica, over an annual cycle in 2011/2012

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Acta Oceanologica Sinica 2019年第5期38卷 51-61页

作者： Jiechen Zhao Qinghua Yang Bin Cheng matti lepp?ranta Fengming Hui Surui Xie Meng Chen Yining Yu Zhongxiang Tian Ming Li Lin Zhang College of Oceanic and Atmospheric Sciences Ocean University of China National Marine Environmental Forecasting Center First Institute of Oceanography Ministry of Natural Resources Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies School of Atmospheric Sciences Sun Yat-sen University Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai) Finnish Meteorological Institute Institute of Atmospheric and Earth Sciences University of Helsinki College of Global Change and Earth System Sciences (GCESS) Beijing Normal University School of Geosciences University of South Florida Meteorological Service of Youyang Tujia and Miao Autonomous County College of Global Change and Earth System Sciences Beijing Normal University

Annual observations of first-year ice(FYI) and second-year ice(SYI) near Zhongshan Station, East Antarctica,were conducted for the first time from December 2011 to December 2012. Melt ponds appeared from early December 2011. Landfast ice partly broke in late January, 2012 after a strong cyclone. Open water was refrozen to form new ice cover in mid-February, and then FYI and SYI co-existed in March with a growth rate of 0.8 cm/d for FYI and a melting rate of 2.7 cm/d for SYI. This difference was due to the oceanic heat flux and the thickness of ice,with weaker heat flux through thicker ice. From May onward, FYI and SYI showed a similar growth by 0.5 cm/*** maximum thickness reached 160.5 cm and 167.0 cm, respectively, in late October. Drillings showed variations of FYI thickness to be generally less than 1.0 cm, but variations were up to 33.0 cm for SYI in March,suggesting that the SYI bottom was particularly uneven. Snow distribution was strongly affected by wind and surface roughness, leading to large thickness differences in the different sites. Snow and ice thickness in Nella Fjord had a similar "east thicker, west thinner" spatial distribution. Easterly prevailing wind and local topography led to this snow pattern. Superimposed ice induced by snow cover melting in summer thickened multi-year ice,causing it to be thicker than the snow-free SYI. The estimated monthly oceanic heat flux was ～30.0 W/m2 in March–May, reducing to ～10.0 W/m2 during July–October, and increasing to ～15.0 W/m2 in November. The seasonal change and mean value of 15.6 W/m2 was similar to the findings of previous research. The results can be used to further our understanding of landfast ice for climate change study and Chinese Antarctic Expedition services.

关键词： landfast ice thickness oceanic heat flux Prydz Bay East Antarctica

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