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A Statistical Linkage between Extreme Cold Wave Events in Southern China and sea ice Extent in the Barents-Kara seas from 1289 to 2017

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Advances in Atmospheric Sciences 2023年第12期40卷 2154-2168页

作者： Cunde XIAO Qi ZHANG Jiao YANG Zhiheng DU Minghu DING Tingfeng DOU Binhe LUO State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

Arctic sea ice loss and the associated enhanced warming has been related to midlatitude weather and climate changes through modulate meridional temperature gradients linked to circulation. However, contrasting lines of evidence result in low confidence in the influence of Arctic warming on midlatitude climate. This study examines the additional perspectives that palaeoclimate evidence provides on the decadal relationship between autumn sea ice extent (SIE) in the Barents-Kara (B-K) seas and extreme cold wave events (ECWEs) in southern China. Reconstruction of the winter Cold Index and SIE in the B-K seas from 1289 to 2017 shows that a significant anti-phase relationship occurred during most periods of decreasing SIE, indicating that cold winters are more likely in low SIE years due to the “bridge” role of the North Atlantic Oscillation and Siberian High. It is confirmed that the recent increase in ECWEs in southern China is closely related to the sea ice decline in the B-K seas. However, our results show that the linkage is unstable, especially in high SIE periods, and it is probably modulated by atmospheric internal variability.

关键词： extreme cold wave events sea ice Barents-Kara(B-K)seas Arctic southern China

Polar sea ice Identification and Classification Based on HY-2A/SCAT Data

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Journal of Ocean University of China 2022年第2期21卷 331-346页

作者： XU Rui ZHAO Chaofang ZHAI Xiaochun ZHAO Ke SHEN Jichang CHEN Ge Department of Marine Technology Ocean University of ChinaQingdao 266100China Laboratory for Regional Oceanography and Numerical Modeling&Department of Satellite Engineering Pilot National Laboratory for Marine Science and Technology(Qingdao)Qingdao 266100China National Satellite Meteorological Center Beijing 100081China

In this paper,a Bayesian sea ice detection algorithm is first used based on the HY-2A/SCAT data,and a backpropagation(BP)neural network is used to classify the Arctic sea ice type.During the implementation of the Bayesian sea ice detection algorithm,linear sea ice model parameters and the backscatter variance suitable for HY-2A/SCAT were proposed.The sea ice extent obtained by the Bayesian sea ice detection algorithm was projected on a 12.5 km grid sea ice map and validated by the Advanced Microwave Scanning Radiometer 2(AMSR2)15%sea ice concentration data.The sea ice extent obtained by the Bayesian sea ice detection al-gorithm was found to be in good agreement with that of the AMSR2 during the ice growth season.Meanwhile,the Bayesian sea ice detection algorithm gave a wider ice edge than the AMSR2 during the ice melting season.For the sea ice type classification,the BP neural network was used to classify the Arctic sea ice type(multi-year and first-year ice)from January to May and October to De-cember in 2014.Comparison results between the HY-2A/SCAT sea ice type and Equal-Area Scalable Earth Grid(EASE-Grid)sea ice age data showed that the HY-2A/SCAT multi-year ice extent variation had the same trend as the EASE-Grid data.Classification errors,defined as the ratio of the mismatched sea ice type points between HY-2A/SCAT and EASE-Grid to the total sea ice points,were less than 12%,and the average classification error was 8.6%for the study period,which indicated that the BP neural network classification was a feasible algorithm for HY-2A/SCAT sea ice type classification.

关键词： sea ice HY-2A/SCAT sea ice identification sea ice type Bayesian sea ice detection BP neural network

Effect of compressive strength on the performance of the NEMO-LIM model in Arctic sea ice simulation

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Journal of Oceanology and Limnology 2023年第1期41卷 1-16页

作者： Chunming DONG Xiaofan LUO Hongtao NIE Wei ZHAO Hao WEI School of Marine Science and Technology Tianjin UniversityTianjin 300072China

Satellite records show that the extent and thickness of sea ice in the Arctic Ocean have significantly decreased since the early 1970s.The prediction of sea ice is highly important,but accurate simulation of sea ice variations remains highly challenging.For improving model performance,sensitivity experiments were conducted using the coupled ocean and sea ice model(NEMO-LIM),and the simulation results were compared against satellite observations.Moreover,the contribution ratios of dynamic and thermodynamic processes to sea ice variations were analyzed.The results show that the performance of the model in reconstructing the spatial distribution of Arctic sea ice is highly sensitive to ice strength decay constant(C^(rhg)).By reducing the C^(rhg) constant,the sea ice compressive strength increases,leading to improved simulated sea ice states.The contribution of thermodynamic processes to sea ice melting was reduced due to less deformation and fracture of sea ice with increased compressive strength.Meanwhile,dynamic processes constrained more sea ice to the central Arctic Ocean and contributed to the increases in ice concentration,reducing the simulation bias in the central Arctic Ocean in summer.The root mean square error(RMSE)between modeled and the CryoSat-2/SMOS satellite observed ice thickness was reduced in the compressive strength-enhanced model solution.The ice thickness,especially of multiyear thick ice,was also reduced and matched with the satellite observation better in the freezing season.These provide an essential foundation on exploring the response of the marine ecosystem and biogeochemical cycling to sea ice changes.

关键词： sea ice compressive strength sensitivity experiment ocean-sea ice model Arctic Ocean

Variability of sea ice from 2008 to 2019 in the Bohai and Northern Huanghai sea, China and the Relationship with Climatic Factors

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Journal of Ocean University of China 2022年第5期21卷 1189-1197页

作者： GONG Shaoqi CHEN Wenqian ZHANG Cunjie YAN Qingyun YANG Hong School of Remote Sensing and Geomatics Engineering Nanjing University of Information Science and TechnologyNanjing 210044China National Climate Center China Meteorological AdministrationBeijing 100081China Department of Geography and Environment Science University of ReadingReading RG66ABUK

sea ice has important effect on the marine ecosystem and people living in the surrounding regions in winter.However,the understanding on changes of sea ice in the Bohai and northern Huanghai sea(BNHS),China is still limited.Based on the images from Visible and InfraRed Radiometer(VIRR)onboard Chinese second generation polar-orbit meteorological series satellites FY-3A/B/C,the sea ice areas in the BNHS were extracted from December 2008 to March 2019,the spatio-temporal distribution charac-teristics of sea ice and the relationship between sea ice area and climatic factors were analyzed,then a preliminary sea ice forecast model based on the climatic factors was developed.The results showed that sea ice area in the BNHS in each December was relatively small and rather high sea ice occurrence probability appeared in the offshore areas in Liaodong Bay and northern Huanghai sea.The sea ice area in January or February each year was the largest,and sea ice occurred in most of areas in Liaodong Bay and northern Huanghai sea with rather high probability and in some areas in Bohai Bay and Laizhou Bay with relatively high probability.How-ever,the sea ice area in each March was the smallest,and sea ice was even melted completely occasionally,hence with relatively low occurrence probability in Liaodong Bay.As for the inter-annual variability of sea ice in the BNHS during the research period,the sea ice area was largest in winter 2010/11 and smallest in winter 2014/15,and annual sea ice area presented a decreasing trend.The at-mospheric temperature,western Pacific subtropical high(WPSH),Asia polar vortex(APV),Asian monsoon circulation(AMC)and Eurasian monsoon circulation(EMC)were very important climatic factors for sea ice formation and they had significant correlations with sea ice area.Therefore,a preliminary sea ice forecast model was constructed by using eight climatic factors including western Pacific subtropical high area index(WPSHAI),western Pacific subtropical high intensity index(WPSHII),western Pacific subtro-pical hi

关键词： sea ice polar-orbit meteorological series satellites FY-3/VIRR Bohai sea climatic factors

Impact of the Shrinkage of Arctic sea ice on Eurasian Snow Cover Changes in 1979-2021

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Advances in Atmospheric Sciences 2023年第12期40卷 2183-2194,I0007,I0008页

作者： Qian YANG Shichang KANG Haipeng YU Yaoxian YANG State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

Recent research has shown that snow cover induces extreme wintertime cooling and has detrimental impacts.Although the dramatic loss of Arctic sea ice certainly has contributed to a more extreme climate,the mechanism connecting sea-ice loss to extensive snow cover is still up for debate.In this study,a significant relationship between sea ice concentration(SIC)in the Barents-Kara(B-K)seas in November and snow cover extent over Eurasia in winter(November-January)has been found based in observational datasets and through numerical experiments.The reduction in B-K sea ice gives rise to a negative phase of Arctic Oscillation(AO),a deepened East Asia trough,and a shallow trough over Europe.These circulation anomalies lead to colder-than-normal Eurasian mid-latitude temperatures,providing favorable conditions for snowfall.In addition,two prominent cyclonic anomalies near Europe and Lake Baikal affect moisture transport and its divergence,which results in increased precipitation due to moisture advection and wind convergence.Furthermore,anomalous E-P flux shows that amplified upward propagating waves associated with the low SIC could contribute to the weakening of the polar vortex and southward breakouts of cold air.This work may be helpful for further understanding and predicting the snowfall conditions in the middle latitudes.

关键词： Arctic Barents-Kara seas sea ice snow cover Eurasia

Characteristics of sea ice kinematics from the marginal ice zone to the packed ice zone observed by buoys deployed during the 9th Chinese Arctic Expedition

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Acta Oceanologica Sinica 2022年第7期41卷 113-127页

作者： Xiaomin Chang Longchun Ye Guangyu Zuo Jingyue Li Keyu Wei Yinke Dou College of Water Resources Science and Engineering Taiyuan University of TechnologyTaiyuan030024China College of Electrical and Power Engineering Taiyuan University of TechnologyTaiyuan030024China

sea ice growth and consolidation play a significant role in heat and momentum exchange between the atmosphere and the ocean.However,few in situ observations of sea ice kinematics have been reported owing to difficulties of deployment of buoys in the marginal ice zone(MIZ).To investigate the characteristics of sea ice kinematics from MIZ to packed ice zone(PIZ),eight drifting buoys designed by Taiyuan University of Technology were deployed in the open water at the ice edge of the Canadian Basin.sea ice near the buoy constantly increased as the buoy drifted,and the kinematics of the buoy changed as the buoy was frozen into the ice.This process can be determined using sea ice concentration,sea skin temperature,and drift speed of buoy together.sea ice concentration data showed that buoys entered the PIZ in mid-October as the ice grew and consolidated around the buoys,with high amplitude,high frequency buoy motions almost ceasing.Our results confirmed that good correlation coefficient in monthly scale between buoy drift and the wind only happened in the ice zone.The correlation coefficient between buoys and wind was below 0.3 while the buoys were in open water.As buoys entered the ice zone,the buoy speed was normally distributed at wind speeds above 6 m/s.The buoy drifted mainly to the right of the wind within 45°at wind speeds above 8 m/s.During further consolidation of the ice in MIZ,the direct forcing on the ice through winds will be lessened.The correlation coefficient value increased to 0.9 in November,and gradually decreased to 0.7 in April.

关键词： sea ice kinematics buoy observations remote sensing marginal ice zone

Numerical Analyses of ice Jamming in Jacket Platform Conductor Array in Bohai sea

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China Ocean Engineering 2023年第6期37卷 885-896页

作者： ZHAI Bi-yao YANG Fan PAN Jun-ning XIE Dong-mei River and Harbour Engineering Department Nanjing Hydraulic Research InstituteNanjing 210029China The National Key Laboratory of Water Disaster Prevention Nanjing 210098China

Serious ice accumulating,pile-up and ice jamming occur around the conductor array of offshore jacket platforms during the winter every year in Bohai sea,which could cause grave threats to the stability of platform structure,the safety of people and equipment,and even severer calamity.Therefore,the process of ice accumulation and ice jamming in the jacket platform area needs more concern.This study focuses on ice accumulation and jamming behaviors in the jacket platform conductor area by using a coupled two-dimensional hydro-ice dynamics model.A series of cases are conducted with different flow conditions,such as flow velocity,drifting direction and oscillatory flow.Through the simulation,the ice pile-up process is described and changes in ice-jamming thickness,ice pile-up location and ice pile-up volume are investigated.The differences in ice pile-up in the steady flow and oscillatory flow are analyzed.This study proposes a new approach to simulate the ice jamming process in the jacket platform conductor area,providing a reference for ice management on the platform.

关键词： sea ice ice jamming conductor array numerical modeling hydro-ice dynamics

Will the summer sea ice in the Arctic reach a tipping point?

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Atmospheric and Oceanic Science Letters 2023年第3期16卷 58-62页

作者： Ola M.Johannessen Elena V.Shalina Nansen Scientific Society BergenNorway Nansen International Environmental and Remote Sensing Centre St PetersburgRussia

The Arctic sea-ice cover has decreased in extent,area,and thickness over the last six decades.Most global climate models project that the summer sea-ice extent(SIE)will decline to less than 1 million(mill.)km^(2) in this century,ranging from 2030 to the end of the century,indicating large uncertainty.However,some models,using the same emission scenarios as required by the Paris Agreement to keep the global temperature below 2°C,indicate that the SIE could be about 2 mill.km^(2) in 2100 but with a large uncertainty of±1.5 mill.km^(2).Here,the authors take another approach by exploring the direct relationship between the SIE and atmospheric CO_(2) concentration for the summer-fall months.The authors correlate the SIE and In(CO_(2)/CO_(2)r)during the period 1979-2022,where CO_(2)r is the reference value in 1979.Using these transient regression equations with an R2 between 0.78 and 0.87,the authors calculate the value that the CO_(2) concentration needs to reach for zero SIE.The results are that,for July,the CO_(2) concentration needs to reach 691±16.5 ppm,for August 604±16.5 ppm,for September 563±17.5 ppm,and for October 620±21 ppm.These values of CO_(2)for an ice-free Arctic are much higher than the targets of the Paris Agreement,which are 450 ppm in 2060 and 425 ppm in 2100,under the IPCC SSP1-2.6 scenario.If these targets can be reached or even almost reached,the "no tipping point"hypothesis for the summer SIE may be valid.

关键词： sea ice Arctic Climate change Tipping point

Productivity in the Southern Ocean Antarctic Zone during the Northern Hemisphere Glaciation(NHG)and its link to atmospheric pCO_(2)

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Science China Earth Sciences 2024年第7期67卷 2242-2252页

作者： Yiming WU Jingteng GUO Xiangyu ZHAO Wenshen XIAO Heng LIU Zhifang XIONG Tiegang LI Key Laboratory of Marine Geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China Laboratory for Marine Geology Laoshan LaboratoryQingdao 266237China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China Key Laboratoryof Polar Eosystem and Climate Change Shanghai Jiao Tong UniversiyMinistryof EducationShanghai 200030China State Key Laboratory of Marine Geology Tongji UniversityShanghai 200092China

A decrease in atmospheric CO_(2)partial pressure(pCO_(2))is considered an important prerequisite for the onset and intensification of Northern Hemisphere Glaciation(NHG).However,how the ocean sequestered missing CO_(2)during the NHG is still uncertain.Changes in surface productivity and deep ventilation in the Southern Ocean(SO)have been proposed to explain the variations in atmospheric pCO_(2)over the last eight glacial cycles,but it is unclear whether these mechanisms contributed to the decrease in atmospheric pCO_(2)during the NHG.Using titanium-normalized contents and mass accumulation rates of biogenic opal and total organic carbon from the International Ocean Discovery Program(IODP)Expedition 374 Site U1524A,we reconstruct the productivity in the Ross sea,Antarctica,from 3.3 Ma to 2.4 Ma.The productivity records exhibit a long-term decreasing trend and several distinct phased evolutionary features.Specifically,the local productivity fluctuated dramatically during 3.3-3.0 Ma,decreased gradually during 3.0-2.6 Ma,and remained relatively constant during 2.6-2.4 Ma.By comparing productivity with its potential influences,we infer that the phased and long-term evolutions of productivity were mainly controlled by changes in deep ocean ventilation.sea ice expansion might have decreased productivity during 3.3-3.0 Ma by light attenuation.Changes in eolian dust input have little effect on productivity.Further analysis revealed no coupling linkage between productivity and atmospheric pCO_(2),indicating that the productivity in the SO Antarctic Zone(AZ)was not the main factor controlling the atmospheric CO_(2)decrease during the NHG.To improve our understanding of the role of SO processes in the NHG,further studies should focus on the potential influences of deep ocean ventilation on atmospheric pCO_(2)in the AZ,and similar studies should also be extended to the sea area in the Subantarctic Zone.

关键词： Ross sea Biogenic opal Total organic carbon Deep ocean ventilation sea ice Ocean carbon cycle