Current shipping,tourism,and resource development requirements call for more accurate predictions of the Arctic sea-ice concentration(SIC).However,due to the complex physical processes involved,predicting the spatiote...Current shipping,tourism,and resource development requirements call for more accurate predictions of the Arctic sea-ice concentration(SIC).However,due to the complex physical processes involved,predicting the spatiotemporal distribution of Arctic SIC is more challenging than predicting its total extent.In this study,spatiotemporal prediction models for monthly Arctic SIC at 1-to 3-month leads are developed based on U-Net-an effective convolutional deep-learning approach.Based on explicit Arctic sea-ice-atmosphere interactions,11 variables associated with Arctic sea-ice variations are selected as predictors,including observed Arctic SIC,atmospheric,oceanic,and heat flux variables at 1-to 3-month leads.The prediction skills for the monthly Arctic SIC of the test set(from January 2018 to December 2022)are evaluated by examining the mean absolute error(MAE)and binary accuracy(BA).Results showed that the U-Net model had lower MAE and higher BA for Arctic SIC compared to two dynamic climate prediction systems(CFSv2 and NorCPM).By analyzing the relative importance of each predictor,the prediction accuracy relies more on the SIC at the 1-month lead,but on the surface net solar radiation flux at 2-to 3-month leads.However,dynamic models show limited prediction skills for surface net solar radiation flux and other physical processes,especially in autumn.Therefore,the U-Net model can be used to capture the connections among these key physical processes associated with Arctic sea ice and thus offers a significant advantage in predicting Arctic SIC.展开更多
Satellite altimetry missions at high latitude have opened new avenues for understanding the changes occurring over the ice-covered region.By incorporating Arctic satellite remote sensing data-including sea surface tem...Satellite altimetry missions at high latitude have opened new avenues for understanding the changes occurring over the ice-covered region.By incorporating Arctic satellite remote sensing data-including sea surface temperature(SST),sea surface height anomaly(SSHA),and sea surface salinity(SSS).This study employs a variational method to reconstruct the three-dimensional thermohaline structure of the Arctic Ocean.Compared to the Regional Arctic Reanalysis(RARE),the reconstruction well captures both the horizontal and vertical temperature and salinity structures in the Arctic.It demonstrates superior skill over RARE,when compared with Argo profiles and Ice-Tethered Profiler(ITP)observations.The reconstruction is particularly effective in ice-covered regions,where it more accurately captures the transition from Pacific water to Atlantic water compared to RARE.These findings underscore the potential of applying Arctic satellite data to reconstruct vertical thermohaline structures in the Arctic,particularly in areas due to lack of the subsurface observation reanalysis data exhibit significant biases.As Arctic satellite observations continue to advance,the applications of this method are becoming increasingly promising,which is useful for monitoring the ice-covered region environment and can be applied to oceanographic research.展开更多
Under ongoing global warming,reliable projections of Arctic sea-ice conditions and future navigability are of strategic significance.Using a combination of observational and physical constraints,we systematically eval...Under ongoing global warming,reliable projections of Arctic sea-ice conditions and future navigability are of strategic significance.Using a combination of observational and physical constraints,we systematically evaluated the performance of 48 Coupled Model Intercomparison Project 6(CMIP6)models in simulating Arctic sea ice and selected 12 skillful models for detailed analysis.Navigability of the Northeast Passage(NEP),Northwest Passage(NWP),and Transpolar Sea Route(TSR)during 2015–2100 was assessed under Shared Socioeconomic Pathways(SSP)2-4.5 and SSP5-8.5 scenarios.Results indicate that for open water vessels under the SSP2-4.5,TSR is not projected to become navigable until 2029.In contrast,under the SSP5-8.5 scenario,both NWP and NEP are expected to support year-round navigation by the late 21st century,while TSR is not anticipated to become fully operational until after 2090.Polar Class 6 vessels achieve near year-round navigation by 2100 under SSP2-4.5,and full-year operation as early as 2048 under SSP5-8.5.展开更多
The year,2024,marks the 40th anniversary of Chinese research expeditions in the polar regions and the 25th anniversary of its Arctic research expeditions.China has conducted 14 national Arctic research expeditions.Wit...The year,2024,marks the 40th anniversary of Chinese research expeditions in the polar regions and the 25th anniversary of its Arctic research expeditions.China has conducted 14 national Arctic research expeditions.With the increase of understandings on the global impacts of the changes of Arctic climate system,especially on China’s weather and climate,and demands for commercial utilization of the Arctic sea routes,Chinese scientists have made great progresses on in site and remote sensing observation technologies for Arctic Ocean,interaction mechanisms between atmosphere,sea ice,and ocean,the connection mechanism between the Arctic Ocean and other regions,and have achieved a series of research results.This study summarizes the research achievements by Chinese scientists in the above-mentioned aspects or beyond,identifies knowledge gaps,and based on this,discusses prospects and provides suggestions.From a perspective of observation,improving the observation capabilities of the Arctic Ocean in winter and the ocean under the ice,as well as floe-scale processes of sea ice and mesoscale and submesoscale processes of the ocean,is an urgent task to be addressed.Strengthening international cooperation is necessary for building a monitoring network for the Arctic marine environment.From a perspective of numerical simulation,the descriptive ability and parameterization scheme of sub-grid processes based on observational evidence need to be developed.From a perspective of cross-sphere interactions,in addition to the multi-media coupling within the Arctic Ocean that this review focuses on,the interaction between the Arctic Ocean and land or ice sheet(Greenland),especially the water cycle process,is also a scientific domain that needs to be considered,in the context of Arctic warming and humidification.From a perspective of climate effects,the physical mechanisms that affect the robustness of teleconnection need to be clarified.展开更多
Arctic climate changes have profoundly influenced the polar environmental changes in recent years.The Arctic Oscillation(AO),as a key component of the Arctic climate system’s internal variability,affects the source t...Arctic climate changes have profoundly influenced the polar environmental changes in recent years.The Arctic Oscillation(AO),as a key component of the Arctic climate system’s internal variability,affects the source to sink processes and interactions across the multilayer Arctic system by regulating the land,ocean,sea ice,and atmospheric processes.The East Siberian Arctic Shelf(ESAS)has experienced significant changes in the input,transport,and burial of sedimentary organic carbon(OC)due to climate warming and shifts in the AO phase in recent decades.This study analyzes grain size,total organic carbon(TOC),total nitrogen(TN),and stable carbon isotope(δ^(13)C)in two sediment cores from the ESAS to reconstruct the burial record of OC over the past few decades and examine the response mechanism of sedimentary OC records to regional-scale climate forcing.The results show that the OC in the two sediment cores originates from mixed sources with a dominant terrestrial contribution.In the LV83-28 core from the Laptev Sea,the TOC and TN contents have increased at an accelerated rate since the 1990s,with a noticeable rise in the contribution of terrestrial OC.This trend is linked to an increase in terrigenous input caused by the positive AO phase.Core LV83-39 in the East Siberian Sea could have accumulated more terrestrial OC transported along the continental shelf during the positive AO.This implies that,under the interannual regulation of the AO regime,the input and crossshelf transport of terrigenous OC in the ESAS showed consistent sedimentary responses.This finding could enhance the understanding of the burial mechanism of sedimentary OC and its environmental response to regional climate change.展开更多
Freely available data of sulfur dioxide (SO2), ammonia (NH3), nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM) observed in Arctic cities (north of 59.99 N) between 1972 and 2016 were compiled into an ai...Freely available data of sulfur dioxide (SO2), ammonia (NH3), nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM) observed in Arctic cities (north of 59.99 N) between 1972 and 2016 were compiled into an air-quality inventory of samples taken for limited periods. For cities with multiple years of data, air-quality climatology was determined in terms of daily means in the annual course. Mean urban air-quality climatology was calculated for regions of similar insolation, emission standards, topography, Köppen-Geiger classification, and city size. Urban concentrations of PM precursors (SO2, NH3, NO2), PM2.5 and PM10 (PM with diameter less than 2.5 and 10 μm) were assessed in the sense of climatology with evidence from current knowledge. Typically, annual SO2 and NO2 means were lower for small than large Arctic cities, but can vary more than an order of magnitude over short distance. Cities seeing seasonal sea-ice had W-shaped mean annual courses of daily O3, while other cities had a spring maximum. Typically, annual means of urban pollutants in North America exceeded those in Scandinavia except for O3, where the opposite was true. Annual mean urban PM2.5 and PM10 concentrations varied from 1.6 to 21.2 μg·m-3 and 2 to 18.2 μg·m-3, respectively. Since PM10 encompasses PM2.5, annual PM10 means must be at least 21.2 μg·m-3. According to rural-to-urban ratios of species, seasonal transport of pollutants from wildfires, shipping, and the Kola Peninsula mining area occurred at some sites in Interior Alaska, western and northern Norway, respectively. Concurrent SO2 and PM or NO2 and PM measurements revealed combustion or traffic as major contributors to urban concentrations. Recommendations for potential future measurements of Arctic urban air quality were given based on the assessments of climatology and inventory.展开更多
The accelerated decline of Arctic sea ice since the 1980s has paradoxically amplified greenhouse gas(GHG)emissions through increased shipping activities in this ecologically vulnerable region.This study investigates h...The accelerated decline of Arctic sea ice since the 1980s has paradoxically amplified greenhouse gas(GHG)emissions through increased shipping activities in this ecologically vulnerable region.This study investigates how to reconcile the decarbonization of Arctic shipping with conflicting environmental,economic,and geopolitical interests.Through systematic literature review and interest-balancing analysis,our findings identify three systemic barriers:(1)inadequate adaptation of International Maritime Organization(IMO)regulations to Arctic-specific environmental risks,(2)fragmented enforcement mechanisms among Arctic and non-Arctic States,and(3)technological limitations in clean fuel adoption for ice-class vessels.To address these challenges,a tripartite governance framework is proposed.First,legally binding amendments to International Convention for the Prevention of Pollution from Ships(MARPOL)Annex VI introducing Arctic-specific Energy Efficiency eXisting ship Index(EEXI)standards and extending energy efficiency regulations to fishing vessels.Second,a phased fuel transition prioritizing liquefied natural gas(LNG)and methanol,followed by hydrogen-ammonia synthetics.Third,enhanced multilateral cooperation through an Arctic Climate Shipping Alliance to coordinate joint research and development in cold-adapted technologies and ice-route optimization.By integrating United Nations Convention on the Law of the Sea(UNCLOS)obligations with IMO Polar Code implementation,this study advances a dynamic interest-balancing framework for policymakers,offering actionable pathways to achieve Paris Agreement targets while safeguarding Arctic ecosystems.展开更多
Arctic sea-ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers(mill.km^(2)). This was not a record low, which occurred in 2012, when the minimum ...Arctic sea-ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers(mill.km^(2)). This was not a record low, which occurred in 2012, when the minimum was 4.175 mill.km^(2), 0.794 mill.km^(2) less than the minimum in 2023. However, the ice extent had decreased by 0.432 mill.km^(2) compared with 2022. Nevertheless, the summer melting in 2023 was remarkably less than expected when considering the strong heat waves in the atmosphere and ocean, with record temperatures set around the world. In general, there is a high correlation between the long-term decrease in sea-ice extent and the increasing CO_(2) in the atmosphere, where the increase of CO_(2) in recent decades explains about 80% of the decrease in sea ice in September, while the remainder is caused by natural variability.展开更多
The Atmospheric Infrared Sounder(AIRS)on the Aqua satellite,along with the MWTS/MWHS Synergy(TSHS)sounding system and Atmospheric Vertical Sounder System(VASS)on the Fengyun-3D(FY-3D)satellite,provide highquality data...The Atmospheric Infrared Sounder(AIRS)on the Aqua satellite,along with the MWTS/MWHS Synergy(TSHS)sounding system and Atmospheric Vertical Sounder System(VASS)on the Fengyun-3D(FY-3D)satellite,provide highquality data for studying Arctic temperature change.The generalized cold bias of AIRS is confirmed through horizontal comparisons with Arctic land radiosonde stations.VASS corrects the warm bias of TSHS by incorporating the Hyperspectral Infrared Atmospheric Sounder-I(HIRAS-I).Vertical comparisons demonstrate that AIRS,TSHS,and VASS offer excellent temperature detection from the top of the boundary layer to the lower stratosphere(800–100 h Pa).However,the overestimation and errors of stratospheric temperatures by TSHS and VASS increase with altitude(pressures below60 h Pa).Specifically,the warm bias trends at 0.06 K hPa^(-1),reaching 2.87 K and 2.92 K at 10 h Pa.Similarly,RMSE values trend at 0.05?K h Pa^(-1),reaching 3.62?K and 3.69?K at 10 h Pa.The low correlation(R≥0.65)of TSHS near 250 h Pa in summer is significantly improved in VASS(R≥0.78)after adding HIRAS-I.The high vertical resolution due to infrared hyperspectral resolution facilitates the detection of complex temperature junctions.The retrieval error of AIRS in the boundary layer increases with cloudiness,while VASS combines microwave and infrared channel data to reduce the impact of cloud cover.Assessing the Arctic applicability of these three satellite temperature profile products will facilitate their widespread use in the Arctic region,enhance accurate climate change monitoring,and further reveal the mechanisms of Arctic warming.展开更多
In the Arctic Ocean,turbulent mixing drives vertical heat flux,thereby affecting the sea ice variability.Internal wave is regarded as one of the important energy sources of mixing in this region.The high latitude and ...In the Arctic Ocean,turbulent mixing drives vertical heat flux,thereby affecting the sea ice variability.Internal wave is regarded as one of the important energy sources of mixing in this region.The high latitude and sea ice cover make internal wave in the Arctic Ocean apparently differs from that in mid-and low-latitude oceans.However,the internal wave and its underlying mechanism are less understood due to the lack of observations.This paper briefly reviews the recent studies and unresolved questions on the internal wave in the Arctic Ocean,including wind-driven near-inertial wave,internal tide,and high-frequency internal wave.The aim is to provide new insights for in-depth research in the future,with a focus on the mechanisms responsible for the evolution of internal wave under the rapidly changing Arctic climate.展开更多
Regarding the rapid shrinkage of the Arctic cryosphere, sea ice plays a significant role in the temporal storage,transport, and release of microplastics(an emergent pollutant) among atmospheric, aquatic, and terrestri...Regarding the rapid shrinkage of the Arctic cryosphere, sea ice plays a significant role in the temporal storage,transport, and release of microplastics(an emergent pollutant) among atmospheric, aquatic, and terrestrial environments. However, there are sparse studies on microplastics in the landfast sea ice and lagoon lake ice in the Alaskan Arctic region. Therefore, this study investigated characteristics and potential sources of microplastics in the landfast sea ice and lagoon lake ice in the Alaskan Arctic(Point Barrow). The results found that the average abundance of microplastics in the landfast sea ice(220.6±140.1 items/L) was comparable to that in lagoon lake ice near Point Barrow(148.9±141.8 items/L). For different layers of sea ice cores, the maximum abundance of microplastics generally occurred in the bottom layer. The overall particle sizes for the detected microplastics revealed that the abundance of microplastics decreased with increasing size for both landfast sea ice and lagoon lake ice samples. Small-sized microplastics(≤50 μm) accounted for more than 80% of the detected microplastics,with the dominant shape being fragments. The predominant polymers in sea ice were polyamide(PA), polyethylene(PE), and polyethylene terephthalate(PET). Meanwhile, PE and rubber dominated the polymers detected in lagoon lake ice. These differences between microplastics in Arctic sea ice and lagoon lake ice further indicated the discrepancies in microplastic transport pathways and deposition. Microplastics in landfast sea ice were mainly affected by seawater transported from the Pacific Ocean into the Chukchi Sea. In contrast, microplastics in lagoon lake ice were mostly influenced by the seawater of the Beaufort Sea and local vehicle emissions(e.g., rubber). This study further highlighted that a large abundance of microplastics was widely distributed in the sea ice of the Alaska Arctic region and may pose potential risks to the local ecosystems.展开更多
With the accelerating effects of global warming,changes in Arctic sea ice extent(SIE)have become a focal point of research.However,due to its spatial heterogeneity and the complexity of its evolution,understanding the...With the accelerating effects of global warming,changes in Arctic sea ice extent(SIE)have become a focal point of research.However,due to its spatial heterogeneity and the complexity of its evolution,understanding the mechanisms driving sea ice remains a significant challenge.This study systematically examines the spatiotemporal variability of Arctic SIE and its coupling mechanisms with atmospheric-oceanic dynamic processes based on passive microwave satellite observations and atmospheric reanalysis datasets.The findings show that during the period from 1979 to 2022(44 a),the SIE exhibited an annual change rate of(−4.36±0.30)×10^(4)km^(2).The most significant decline was observed in summer[(−7.39±0.48)×10^(4)km^(2)/a].In contrast,the decrease in winter sea ice concentration(SIC)was primarily observed in the Barents Sea and Kara Sea.Meanwhile,persistent SIC retreat was observed across most of the Arctic during spring,summer and autumn.To quantify the contributions of environmental factors,the study employs multiple approaches,which reveal that sea surface temperature is the most influential factor.Furthermore,meteorological statistical methods are used to investigate how climate patterns regulate SIC by influencing Arctic atmospheric circulation.These findings highlight the intricate interactions among Arctic atmosphere,ocean,SIE and climate patterns,providing a theoretical framework and scientific basis for understanding the evolution of SIE.展开更多
The Arctic is one of Earth’s regions highly susceptible to climate change.However,in situ long-term observations used for climate research are relatively sparse in the Arctic Ocean,and current climate models exhibit ...The Arctic is one of Earth’s regions highly susceptible to climate change.However,in situ long-term observations used for climate research are relatively sparse in the Arctic Ocean,and current climate models exhibit notable biases in Arctic Ocean simulations.Here,we present an Arctic Ocean dynamical downscaling dataset,obtained from the global ocean-sea ice model FESOM2 with a regionally refined horizonal resolution of 4.5 km in the Arctic region,which is driven by bias-corrected surface forcings derived from a climate model.The dataset includes 115 years(1900-2014)of historical simulations and two 86-year future projection simulations(2015-2100)for the SSP2-4.5 and SSP5-8.5 scenarios.The historical simulations demonstrate substantially reduced biases in temperature,salinity and sea-ice thickness compared to CMIP6 climate models.Common biases in the representation of the Atlantic Water layer found in climate model simulations are also markedly reduced in the dataset.Serving as a crucial long-term data source for climate change assessments and scientific research for the Arctic Ocean,this dataset provides valuable information for the scientific community.展开更多
Scientists from the UK recently visited the Arctic to test out a method of“refreezing”its ice.The Arctic is in the northernmost part of Earth,and is extremely cold,but the ice is melting due to global warming.Over t...Scientists from the UK recently visited the Arctic to test out a method of“refreezing”its ice.The Arctic is in the northernmost part of Earth,and is extremely cold,but the ice is melting due to global warming.Over the past 30 years,the oldest and thickest parts have shrunk by as much as 95%.The melting ice causes sea levels to rise.It also makes the planet warmer.Because the dark water takes in the Sun’s heat,while the white ice reflects it back into space.展开更多
A halocline in the Arctic Ocean significantly slows the upward heat flux from deep warm water,thereby inhibiting the melting of surface sea ice.The western Arctic Ocean exhibits a double-halocline(DH)structure due to ...A halocline in the Arctic Ocean significantly slows the upward heat flux from deep warm water,thereby inhibiting the melting of surface sea ice.The western Arctic Ocean exhibits a double-halocline(DH)structure due to the complexity of the water mass.Using in situ measurements,we analyzed the vertical structural characteristics of DH and its interannual variation.The results indicated that the DH primarily occurs at the Northwind Ridge and the southern Canada Basin,extending westward to the Chukchi Abyssal Plain and northward to the northern boundary of the Canada Basin.From 2002 to 2022,there were changes in water masses that determined the structure of the DH.The significant increase in Pacific Water has resulted in 42%and 65%increases in freshwater and the heat content of the DH,respectively,along with a 14%reduction in stratification.Pacific Winter Water characterized by salinity of 33 has exhibited a gradually decreasing trend,suggesting that the lower halocline may be difficult to ventilate.The combined effects of Ekman pumping,mesoscale eddies,and positive buoyancy forcing(heat and freshwater input)from Pacific Water have altered the thickness and stratification of the DH.This study has enhanced our understanding of the evolution of vertical heat flux in the upper western Arctic Ocean.展开更多
The thaw-freezing transition period is crucial to determine the initial sea ice status prior to the freezing season.The heat and mass balance at ice-ocean interface is the major driving process.In this study,we analyz...The thaw-freezing transition period is crucial to determine the initial sea ice status prior to the freezing season.The heat and mass balance at ice-ocean interface is the major driving process.In this study,we analyze heat fluxes profile through the ice from ice surface down to basal ice-ocean interface using the data measured by 11 thermistor stringbased ice mass balance buoys(IMBs)between September and December 2018 in the Pacific sector of Arctic Ocean.The conductive heat fluxes gradually decreased from surface downward through the lower ice layers due to the thermal inertia and energy storage in the brine pockets.At the ice bottom,the oceanic heat flux decreased from(5.9±1.3)W/m^(2)in mid-September to(1.8±0.8)W/m^(2)by the end of December in response to the decreasing of available absorbed solar radiation regulated by the latitude and sea ice concentration.The initial ice thicknesses can explain the onset of ice basal growth by 44.8%(R^(2)).From 15 September to the average onset of ice basal growth by 13 November,the accumulated heat fluxes released from the ice surface to the atmosphere,caused by the cooling of the ice layer,and from the ocean to the ice bottom were estimated as 25.73 MJ/m^(2),6.49 MJ/m^(2),and 20.30 MJ/m^(2),respectively.The latter two components mainly play the roles in buffering the onset of ice basal growth.展开更多
This paper explores the archaeology of whaling in Arctic prehistory,focusing on the emergence and development of whaling as a central component of cultural ecology among prehistoric Inuit and related societies.Drawing...This paper explores the archaeology of whaling in Arctic prehistory,focusing on the emergence and development of whaling as a central component of cultural ecology among prehistoric Inuit and related societies.Drawing on archaeological evidence from key sites across Alaska,the Chukchi Peninsula,and the Bering Strait region,the study examines how whaling technologies and practices evolved alongside climatic fluctuations,ecological shifts,and social transformations.Integrating ethnographic insights and paleoclimatic data,the study argues that Inuit engagement with whales was not only a subsistence strategy but a long-term,historically contingent relationship that shaped and was shaped by broader cultural systems.展开更多
In August 2019,accompanied by an Arctic warming event,elevated thunderstorms crossed over the North Pole(NP)and produced lightning.The northernmost stroke occurred less than 50 km from the NP,marking the closest strok...In August 2019,accompanied by an Arctic warming event,elevated thunderstorms crossed over the North Pole(NP)and produced lightning.The northernmost stroke occurred less than 50 km from the NP,marking the closest stroke to the NP ever recorded.Using ERA5 reanalysis data and satellite observations,we investigated the background and development mechanism of this event.Warm and moist air from low latitudes was transported northward to the vicinity of the North Pole by the 850-h Pa jet,resulting in convergence.Through the combined effects of frontal lifting and the presence of underlying cold air,the warm and moist air was lifted to heights above the melting layer,triggering elevated thunderstorms above the frontal boundary.These findings describe a strong link between warming events and thunderstorms,revealing the formation mechanisms of elevated thunderstorms in the Arctic.In the context of rapid Arctic warming,this study provides preliminary insights into the meteorological conditions conducive to thunderstorm formation in the region.展开更多
Using nine ice-tethered buoys deployed across the marginal ice zone(MIZ)and pack ice zone(PIZ)north of the Laptev Sea during the expedition of the Multidisciplinary drifting Observatory for the Study of Arctic Climate...Using nine ice-tethered buoys deployed across the marginal ice zone(MIZ)and pack ice zone(PIZ)north of the Laptev Sea during the expedition of the Multidisciplinary drifting Observatory for the Study of Arctic Climate(MOSAiC)in 2019-2020,we characterized the spatiotemporal variations in sea ice kinematics and deformation between October 2019 and July 2020 in the Transpolar Drift(TPD).From October to November,the buoys were in the upstream area of the TPD;spatial variations of deformation rates were significantly correlated with initial ice thickness(R=−0.84,P<0.05).From December 2019 to March 2020,the buoys were in the high Arctic and the ice cover was consolidated;heterogeneity in ice kinematics as measured across the buoys reduced by 65%.From April to May 2020,the buoys were in the downstream TPD;amplified spatial variations in ice kinematics were observed.This is because two buoys had drifted over the shallow waters north of Svalbard earlier;trajectory-stretching exponents derived from the data from these two buoys indicate deformation rates(10.6 d^(−1))that were about twice those in the deep basin(4.2 d^(−1)).By June 2020,a less consolidated ice pack and enhanced tidal forcing in the Fram Strait MIZ resulted in ice deformation with a semi-diurnal power spectral density of>0.25 d^(−1),which is about 1.5 times that in PIZ.Therefore,in both the upstream and downstream regions of the TPD,the transition between the MIZ and the PIZ contributes to the spatial and seasonal variations of sea ice motion and deformation.The results from this study can be used to support the characterization of the momentum balance and influencing factors during the ice advection along the TPD,which is a crucial corridor for Arctic sea ice outflow to the north Atlantic Ocean.展开更多
The Arctic plays a pivotal role in the Earth’s climate system,with its rapid transformation exerting profound impacts on global climate dynamics,ecosystems,and human societies.In recent decades,Arctic warming has sig...The Arctic plays a pivotal role in the Earth’s climate system,with its rapid transformation exerting profound impacts on global climate dynamics,ecosystems,and human societies.In recent decades,Arctic warming has significantly outpaced the global mean temperature increase,driving the enhanced sea ice decline,the accelerated mass loss of the Greenland Ice Sheet,permafrost degradation,and glacier retreat.These changes modulate atmospheric and oceanic circulation patterns,establishing teleconnections with mid-and low-latitude climate systems.Investigating the historical evolution,current state,and projected future trends of the Arctic climate system,as well as its global impacts,is crucial for elucidating the mechanisms underlying Arctic amplification,refining climate change projections,attributing extreme weather and climate events,and informing sustainable development strategies.展开更多
基金supported by the National Key Research and Development Program of China[grant number 2022YFE0106800]an Innovation Group Project of the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number 311024001]+3 种基金a project supported by the Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)[grant number SML2023SP209]a Research Council of Norway funded project(MAPARC)[grant number 328943]a Nansen Center´s basic institutional funding[grant number 342624]the high-performance computing support from the School of Atmospheric Science at Sun Yat-sen University。
文摘Current shipping,tourism,and resource development requirements call for more accurate predictions of the Arctic sea-ice concentration(SIC).However,due to the complex physical processes involved,predicting the spatiotemporal distribution of Arctic SIC is more challenging than predicting its total extent.In this study,spatiotemporal prediction models for monthly Arctic SIC at 1-to 3-month leads are developed based on U-Net-an effective convolutional deep-learning approach.Based on explicit Arctic sea-ice-atmosphere interactions,11 variables associated with Arctic sea-ice variations are selected as predictors,including observed Arctic SIC,atmospheric,oceanic,and heat flux variables at 1-to 3-month leads.The prediction skills for the monthly Arctic SIC of the test set(from January 2018 to December 2022)are evaluated by examining the mean absolute error(MAE)and binary accuracy(BA).Results showed that the U-Net model had lower MAE and higher BA for Arctic SIC compared to two dynamic climate prediction systems(CFSv2 and NorCPM).By analyzing the relative importance of each predictor,the prediction accuracy relies more on the SIC at the 1-month lead,but on the surface net solar radiation flux at 2-to 3-month leads.However,dynamic models show limited prediction skills for surface net solar radiation flux and other physical processes,especially in autumn.Therefore,the U-Net model can be used to capture the connections among these key physical processes associated with Arctic sea ice and thus offers a significant advantage in predicting Arctic SIC.
基金The National Key R&D Program of China under contract No.2022YFE0106400the China Scholarship Council under contract No.202206710071+2 种基金the Postgraduate Research&Practice Innovation Program of Jiangsu Province under contract No.KYCX23_0657the Special Founds for Creative Research under contract No.2022C61540the Opening Project of the Key Laboratory of Marine Environmental Information Technology under contract No.521037412.
文摘Satellite altimetry missions at high latitude have opened new avenues for understanding the changes occurring over the ice-covered region.By incorporating Arctic satellite remote sensing data-including sea surface temperature(SST),sea surface height anomaly(SSHA),and sea surface salinity(SSS).This study employs a variational method to reconstruct the three-dimensional thermohaline structure of the Arctic Ocean.Compared to the Regional Arctic Reanalysis(RARE),the reconstruction well captures both the horizontal and vertical temperature and salinity structures in the Arctic.It demonstrates superior skill over RARE,when compared with Argo profiles and Ice-Tethered Profiler(ITP)observations.The reconstruction is particularly effective in ice-covered regions,where it more accurately captures the transition from Pacific water to Atlantic water compared to RARE.These findings underscore the potential of applying Arctic satellite data to reconstruct vertical thermohaline structures in the Arctic,particularly in areas due to lack of the subsurface observation reanalysis data exhibit significant biases.As Arctic satellite observations continue to advance,the applications of this method are becoming increasingly promising,which is useful for monitoring the ice-covered region environment and can be applied to oceanographic research.
基金supported by the National Natural Science Foundation of China(Grant no.42430411)the National Key Research and Development Program of China(Grant no.2019YFA0607004)+1 种基金the National Natural Science Foundation of China(Grant no.42075024)the Innovation and Development Program of China Meteorological Administration(Grant no.CXFZ2024J033).
文摘Under ongoing global warming,reliable projections of Arctic sea-ice conditions and future navigability are of strategic significance.Using a combination of observational and physical constraints,we systematically evaluated the performance of 48 Coupled Model Intercomparison Project 6(CMIP6)models in simulating Arctic sea ice and selected 12 skillful models for detailed analysis.Navigability of the Northeast Passage(NEP),Northwest Passage(NWP),and Transpolar Sea Route(TSR)during 2015–2100 was assessed under Shared Socioeconomic Pathways(SSP)2-4.5 and SSP5-8.5 scenarios.Results indicate that for open water vessels under the SSP2-4.5,TSR is not projected to become navigable until 2029.In contrast,under the SSP5-8.5 scenario,both NWP and NEP are expected to support year-round navigation by the late 21st century,while TSR is not anticipated to become fully operational until after 2090.Polar Class 6 vessels achieve near year-round navigation by 2100 under SSP2-4.5,and full-year operation as early as 2048 under SSP5-8.5.
基金The National Natural Science Foundation of China under contract Nos 42325604 and 42276253the Program of Shanghai Academic/Technology Research Leader under contract No.22XD1403600the Fund of the Ministry of Industry and Information Technology of China under contract No.CBG2N21-2-1.
文摘The year,2024,marks the 40th anniversary of Chinese research expeditions in the polar regions and the 25th anniversary of its Arctic research expeditions.China has conducted 14 national Arctic research expeditions.With the increase of understandings on the global impacts of the changes of Arctic climate system,especially on China’s weather and climate,and demands for commercial utilization of the Arctic sea routes,Chinese scientists have made great progresses on in site and remote sensing observation technologies for Arctic Ocean,interaction mechanisms between atmosphere,sea ice,and ocean,the connection mechanism between the Arctic Ocean and other regions,and have achieved a series of research results.This study summarizes the research achievements by Chinese scientists in the above-mentioned aspects or beyond,identifies knowledge gaps,and based on this,discusses prospects and provides suggestions.From a perspective of observation,improving the observation capabilities of the Arctic Ocean in winter and the ocean under the ice,as well as floe-scale processes of sea ice and mesoscale and submesoscale processes of the ocean,is an urgent task to be addressed.Strengthening international cooperation is necessary for building a monitoring network for the Arctic marine environment.From a perspective of numerical simulation,the descriptive ability and parameterization scheme of sub-grid processes based on observational evidence need to be developed.From a perspective of cross-sphere interactions,in addition to the multi-media coupling within the Arctic Ocean that this review focuses on,the interaction between the Arctic Ocean and land or ice sheet(Greenland),especially the water cycle process,is also a scientific domain that needs to be considered,in the context of Arctic warming and humidification.From a perspective of climate effects,the physical mechanisms that affect the robustness of teleconnection need to be clarified.
基金The National Natural Science Foundation of China under contract Nos 42130412 and 42376068the Fundamental Research Funds for the Central Universities under contract No.202241001+2 种基金the Ocean Negative Carbon Emissions Program and the Taishan Scholar Program under contract No.TSQN20182117the Russian Scientific Foundation under contract No.21-77-30001the Ministry of Science and Higher Education of the Russian Federation under contract Nos 124022100083-1 and 124022100084-8.
文摘Arctic climate changes have profoundly influenced the polar environmental changes in recent years.The Arctic Oscillation(AO),as a key component of the Arctic climate system’s internal variability,affects the source to sink processes and interactions across the multilayer Arctic system by regulating the land,ocean,sea ice,and atmospheric processes.The East Siberian Arctic Shelf(ESAS)has experienced significant changes in the input,transport,and burial of sedimentary organic carbon(OC)due to climate warming and shifts in the AO phase in recent decades.This study analyzes grain size,total organic carbon(TOC),total nitrogen(TN),and stable carbon isotope(δ^(13)C)in two sediment cores from the ESAS to reconstruct the burial record of OC over the past few decades and examine the response mechanism of sedimentary OC records to regional-scale climate forcing.The results show that the OC in the two sediment cores originates from mixed sources with a dominant terrestrial contribution.In the LV83-28 core from the Laptev Sea,the TOC and TN contents have increased at an accelerated rate since the 1990s,with a noticeable rise in the contribution of terrestrial OC.This trend is linked to an increase in terrigenous input caused by the positive AO phase.Core LV83-39 in the East Siberian Sea could have accumulated more terrestrial OC transported along the continental shelf during the positive AO.This implies that,under the interannual regulation of the AO regime,the input and crossshelf transport of terrigenous OC in the ESAS showed consistent sedimentary responses.This finding could enhance the understanding of the burial mechanism of sedimentary OC and its environmental response to regional climate change.
文摘Freely available data of sulfur dioxide (SO2), ammonia (NH3), nitrogen dioxide (NO2), ozone (O3), and particulate matter (PM) observed in Arctic cities (north of 59.99 N) between 1972 and 2016 were compiled into an air-quality inventory of samples taken for limited periods. For cities with multiple years of data, air-quality climatology was determined in terms of daily means in the annual course. Mean urban air-quality climatology was calculated for regions of similar insolation, emission standards, topography, Köppen-Geiger classification, and city size. Urban concentrations of PM precursors (SO2, NH3, NO2), PM2.5 and PM10 (PM with diameter less than 2.5 and 10 μm) were assessed in the sense of climatology with evidence from current knowledge. Typically, annual SO2 and NO2 means were lower for small than large Arctic cities, but can vary more than an order of magnitude over short distance. Cities seeing seasonal sea-ice had W-shaped mean annual courses of daily O3, while other cities had a spring maximum. Typically, annual means of urban pollutants in North America exceeded those in Scandinavia except for O3, where the opposite was true. Annual mean urban PM2.5 and PM10 concentrations varied from 1.6 to 21.2 μg·m-3 and 2 to 18.2 μg·m-3, respectively. Since PM10 encompasses PM2.5, annual PM10 means must be at least 21.2 μg·m-3. According to rural-to-urban ratios of species, seasonal transport of pollutants from wildfires, shipping, and the Kola Peninsula mining area occurred at some sites in Interior Alaska, western and northern Norway, respectively. Concurrent SO2 and PM or NO2 and PM measurements revealed combustion or traffic as major contributors to urban concentrations. Recommendations for potential future measurements of Arctic urban air quality were given based on the assessments of climatology and inventory.
基金supported by the Major Research Projects of the National Social Science Fund of China(NSFC,Grant no.23VHQ015).
文摘The accelerated decline of Arctic sea ice since the 1980s has paradoxically amplified greenhouse gas(GHG)emissions through increased shipping activities in this ecologically vulnerable region.This study investigates how to reconcile the decarbonization of Arctic shipping with conflicting environmental,economic,and geopolitical interests.Through systematic literature review and interest-balancing analysis,our findings identify three systemic barriers:(1)inadequate adaptation of International Maritime Organization(IMO)regulations to Arctic-specific environmental risks,(2)fragmented enforcement mechanisms among Arctic and non-Arctic States,and(3)technological limitations in clean fuel adoption for ice-class vessels.To address these challenges,a tripartite governance framework is proposed.First,legally binding amendments to International Convention for the Prevention of Pollution from Ships(MARPOL)Annex VI introducing Arctic-specific Energy Efficiency eXisting ship Index(EEXI)standards and extending energy efficiency regulations to fishing vessels.Second,a phased fuel transition prioritizing liquefied natural gas(LNG)and methanol,followed by hydrogen-ammonia synthetics.Third,enhanced multilateral cooperation through an Arctic Climate Shipping Alliance to coordinate joint research and development in cold-adapted technologies and ice-route optimization.By integrating United Nations Convention on the Law of the Sea(UNCLOS)obligations with IMO Polar Code implementation,this study advances a dynamic interest-balancing framework for policymakers,offering actionable pathways to achieve Paris Agreement targets while safeguarding Arctic ecosystems.
文摘Arctic sea-ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers(mill.km^(2)). This was not a record low, which occurred in 2012, when the minimum was 4.175 mill.km^(2), 0.794 mill.km^(2) less than the minimum in 2023. However, the ice extent had decreased by 0.432 mill.km^(2) compared with 2022. Nevertheless, the summer melting in 2023 was remarkably less than expected when considering the strong heat waves in the atmosphere and ocean, with record temperatures set around the world. In general, there is a high correlation between the long-term decrease in sea-ice extent and the increasing CO_(2) in the atmosphere, where the increase of CO_(2) in recent decades explains about 80% of the decrease in sea ice in September, while the remainder is caused by natural variability.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFC2807204 and 2022YFE0106700)the Basic Research Fund of the Chinese Academy of Meteorological Sciences(Grant Nos.2023Z004,2023Z015,and 2023Y012)。
文摘The Atmospheric Infrared Sounder(AIRS)on the Aqua satellite,along with the MWTS/MWHS Synergy(TSHS)sounding system and Atmospheric Vertical Sounder System(VASS)on the Fengyun-3D(FY-3D)satellite,provide highquality data for studying Arctic temperature change.The generalized cold bias of AIRS is confirmed through horizontal comparisons with Arctic land radiosonde stations.VASS corrects the warm bias of TSHS by incorporating the Hyperspectral Infrared Atmospheric Sounder-I(HIRAS-I).Vertical comparisons demonstrate that AIRS,TSHS,and VASS offer excellent temperature detection from the top of the boundary layer to the lower stratosphere(800–100 h Pa).However,the overestimation and errors of stratospheric temperatures by TSHS and VASS increase with altitude(pressures below60 h Pa).Specifically,the warm bias trends at 0.06 K hPa^(-1),reaching 2.87 K and 2.92 K at 10 h Pa.Similarly,RMSE values trend at 0.05?K h Pa^(-1),reaching 3.62?K and 3.69?K at 10 h Pa.The low correlation(R≥0.65)of TSHS near 250 h Pa in summer is significantly improved in VASS(R≥0.78)after adding HIRAS-I.The high vertical resolution due to infrared hyperspectral resolution facilitates the detection of complex temperature junctions.The retrieval error of AIRS in the boundary layer increases with cloudiness,while VASS combines microwave and infrared channel data to reduce the impact of cloud cover.Assessing the Arctic applicability of these three satellite temperature profile products will facilitate their widespread use in the Arctic region,enhance accurate climate change monitoring,and further reveal the mechanisms of Arctic warming.
基金supported by the National Natural Science Foundation of China(Grant no.42176244)CAS Key Deployment Project of Centre for Ocean Mega-Research of Science(Grant no.COMS2020Q07)。
文摘In the Arctic Ocean,turbulent mixing drives vertical heat flux,thereby affecting the sea ice variability.Internal wave is regarded as one of the important energy sources of mixing in this region.The high latitude and sea ice cover make internal wave in the Arctic Ocean apparently differs from that in mid-and low-latitude oceans.However,the internal wave and its underlying mechanism are less understood due to the lack of observations.This paper briefly reviews the recent studies and unresolved questions on the internal wave in the Arctic Ocean,including wind-driven near-inertial wave,internal tide,and high-frequency internal wave.The aim is to provide new insights for in-depth research in the future,with a focus on the mechanisms responsible for the evolution of internal wave under the rapidly changing Arctic climate.
基金supported by the National Key Research and Development Program of China(2020YFA0608503)the Science and Technology Program of Gansu Province(23ZDFA017).
文摘Regarding the rapid shrinkage of the Arctic cryosphere, sea ice plays a significant role in the temporal storage,transport, and release of microplastics(an emergent pollutant) among atmospheric, aquatic, and terrestrial environments. However, there are sparse studies on microplastics in the landfast sea ice and lagoon lake ice in the Alaskan Arctic region. Therefore, this study investigated characteristics and potential sources of microplastics in the landfast sea ice and lagoon lake ice in the Alaskan Arctic(Point Barrow). The results found that the average abundance of microplastics in the landfast sea ice(220.6±140.1 items/L) was comparable to that in lagoon lake ice near Point Barrow(148.9±141.8 items/L). For different layers of sea ice cores, the maximum abundance of microplastics generally occurred in the bottom layer. The overall particle sizes for the detected microplastics revealed that the abundance of microplastics decreased with increasing size for both landfast sea ice and lagoon lake ice samples. Small-sized microplastics(≤50 μm) accounted for more than 80% of the detected microplastics,with the dominant shape being fragments. The predominant polymers in sea ice were polyamide(PA), polyethylene(PE), and polyethylene terephthalate(PET). Meanwhile, PE and rubber dominated the polymers detected in lagoon lake ice. These differences between microplastics in Arctic sea ice and lagoon lake ice further indicated the discrepancies in microplastic transport pathways and deposition. Microplastics in landfast sea ice were mainly affected by seawater transported from the Pacific Ocean into the Chukchi Sea. In contrast, microplastics in lagoon lake ice were mostly influenced by the seawater of the Beaufort Sea and local vehicle emissions(e.g., rubber). This study further highlighted that a large abundance of microplastics was widely distributed in the sea ice of the Alaska Arctic region and may pose potential risks to the local ecosystems.
基金The National Natural Science Foundation of China under contract Nos 42430101,42274006,42192535 and 42104084.
文摘With the accelerating effects of global warming,changes in Arctic sea ice extent(SIE)have become a focal point of research.However,due to its spatial heterogeneity and the complexity of its evolution,understanding the mechanisms driving sea ice remains a significant challenge.This study systematically examines the spatiotemporal variability of Arctic SIE and its coupling mechanisms with atmospheric-oceanic dynamic processes based on passive microwave satellite observations and atmospheric reanalysis datasets.The findings show that during the period from 1979 to 2022(44 a),the SIE exhibited an annual change rate of(−4.36±0.30)×10^(4)km^(2).The most significant decline was observed in summer[(−7.39±0.48)×10^(4)km^(2)/a].In contrast,the decrease in winter sea ice concentration(SIC)was primarily observed in the Barents Sea and Kara Sea.Meanwhile,persistent SIC retreat was observed across most of the Arctic during spring,summer and autumn.To quantify the contributions of environmental factors,the study employs multiple approaches,which reveal that sea surface temperature is the most influential factor.Furthermore,meteorological statistical methods are used to investigate how climate patterns regulate SIC by influencing Arctic atmospheric circulation.These findings highlight the intricate interactions among Arctic atmosphere,ocean,SIE and climate patterns,providing a theoretical framework and scientific basis for understanding the evolution of SIE.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFF0804600)the National Natural Science Foundation of China(Grant Nos.42276253 and 41821004)+1 种基金the Shandong Provincial Natural Science Foundation(Grant No.ZR2022JQ17)the Taishan Scholar Foundation of Shandong Province(Grant No.tsqn202211264).
文摘The Arctic is one of Earth’s regions highly susceptible to climate change.However,in situ long-term observations used for climate research are relatively sparse in the Arctic Ocean,and current climate models exhibit notable biases in Arctic Ocean simulations.Here,we present an Arctic Ocean dynamical downscaling dataset,obtained from the global ocean-sea ice model FESOM2 with a regionally refined horizonal resolution of 4.5 km in the Arctic region,which is driven by bias-corrected surface forcings derived from a climate model.The dataset includes 115 years(1900-2014)of historical simulations and two 86-year future projection simulations(2015-2100)for the SSP2-4.5 and SSP5-8.5 scenarios.The historical simulations demonstrate substantially reduced biases in temperature,salinity and sea-ice thickness compared to CMIP6 climate models.Common biases in the representation of the Atlantic Water layer found in climate model simulations are also markedly reduced in the dataset.Serving as a crucial long-term data source for climate change assessments and scientific research for the Arctic Ocean,this dataset provides valuable information for the scientific community.
文摘Scientists from the UK recently visited the Arctic to test out a method of“refreezing”its ice.The Arctic is in the northernmost part of Earth,and is extremely cold,but the ice is melting due to global warming.Over the past 30 years,the oldest and thickest parts have shrunk by as much as 95%.The melting ice causes sea levels to rise.It also makes the planet warmer.Because the dark water takes in the Sun’s heat,while the white ice reflects it back into space.
基金The National Key Research and Development Program of China under contract No.2023YFC2809101the National Natural Science Foundation of China under contract No.42276239.
文摘A halocline in the Arctic Ocean significantly slows the upward heat flux from deep warm water,thereby inhibiting the melting of surface sea ice.The western Arctic Ocean exhibits a double-halocline(DH)structure due to the complexity of the water mass.Using in situ measurements,we analyzed the vertical structural characteristics of DH and its interannual variation.The results indicated that the DH primarily occurs at the Northwind Ridge and the southern Canada Basin,extending westward to the Chukchi Abyssal Plain and northward to the northern boundary of the Canada Basin.From 2002 to 2022,there were changes in water masses that determined the structure of the DH.The significant increase in Pacific Water has resulted in 42%and 65%increases in freshwater and the heat content of the DH,respectively,along with a 14%reduction in stratification.Pacific Winter Water characterized by salinity of 33 has exhibited a gradually decreasing trend,suggesting that the lower halocline may be difficult to ventilate.The combined effects of Ekman pumping,mesoscale eddies,and positive buoyancy forcing(heat and freshwater input)from Pacific Water have altered the thickness and stratification of the DH.This study has enhanced our understanding of the evolution of vertical heat flux in the upper western Arctic Ocean.
基金The National Key Research and Development Program of China under contract No.2021YFC2803300the National Natural Science Foundation of China under contract No.42325604+1 种基金the Ministry of Industry and Information Technology of China under contract No.CBG2N21-2-1Program of Shanghai Academic/Technology Research Leader under contract No.22XD1403600.
文摘The thaw-freezing transition period is crucial to determine the initial sea ice status prior to the freezing season.The heat and mass balance at ice-ocean interface is the major driving process.In this study,we analyze heat fluxes profile through the ice from ice surface down to basal ice-ocean interface using the data measured by 11 thermistor stringbased ice mass balance buoys(IMBs)between September and December 2018 in the Pacific sector of Arctic Ocean.The conductive heat fluxes gradually decreased from surface downward through the lower ice layers due to the thermal inertia and energy storage in the brine pockets.At the ice bottom,the oceanic heat flux decreased from(5.9±1.3)W/m^(2)in mid-September to(1.8±0.8)W/m^(2)by the end of December in response to the decreasing of available absorbed solar radiation regulated by the latitude and sea ice concentration.The initial ice thicknesses can explain the onset of ice basal growth by 44.8%(R^(2)).From 15 September to the average onset of ice basal growth by 13 November,the accumulated heat fluxes released from the ice surface to the atmosphere,caused by the cooling of the ice layer,and from the ocean to the ice bottom were estimated as 25.73 MJ/m^(2),6.49 MJ/m^(2),and 20.30 MJ/m^(2),respectively.The latter two components mainly play the roles in buffering the onset of ice basal growth.
文摘This paper explores the archaeology of whaling in Arctic prehistory,focusing on the emergence and development of whaling as a central component of cultural ecology among prehistoric Inuit and related societies.Drawing on archaeological evidence from key sites across Alaska,the Chukchi Peninsula,and the Bering Strait region,the study examines how whaling technologies and practices evolved alongside climatic fluctuations,ecological shifts,and social transformations.Integrating ethnographic insights and paleoclimatic data,the study argues that Inuit engagement with whales was not only a subsistence strategy but a long-term,historically contingent relationship that shaped and was shaped by broader cultural systems.
基金supported by the National Key Research and Development Program of China(2023YFC3007703)National Natural Science Foundation of China(Grant Nos.41675066,42394122)+1 种基金CAS Project of Stable Support for Youth Team in Basic Research Field(YSRR-018)the Chinese Meridian Project。
文摘In August 2019,accompanied by an Arctic warming event,elevated thunderstorms crossed over the North Pole(NP)and produced lightning.The northernmost stroke occurred less than 50 km from the NP,marking the closest stroke to the NP ever recorded.Using ERA5 reanalysis data and satellite observations,we investigated the background and development mechanism of this event.Warm and moist air from low latitudes was transported northward to the vicinity of the North Pole by the 850-h Pa jet,resulting in convergence.Through the combined effects of frontal lifting and the presence of underlying cold air,the warm and moist air was lifted to heights above the melting layer,triggering elevated thunderstorms above the frontal boundary.These findings describe a strong link between warming events and thunderstorms,revealing the formation mechanisms of elevated thunderstorms in the Arctic.In the context of rapid Arctic warming,this study provides preliminary insights into the meteorological conditions conducive to thunderstorm formation in the region.
基金supported by the National Key Research and Development Program of China(Grant no.2021YFC2803304)the National Natural Science Foundation of China(Grant nos.52192691 and 52192690)the Program of Shanghai Academic/Technology Research Leader(Grant no.22XD1403600).
文摘Using nine ice-tethered buoys deployed across the marginal ice zone(MIZ)and pack ice zone(PIZ)north of the Laptev Sea during the expedition of the Multidisciplinary drifting Observatory for the Study of Arctic Climate(MOSAiC)in 2019-2020,we characterized the spatiotemporal variations in sea ice kinematics and deformation between October 2019 and July 2020 in the Transpolar Drift(TPD).From October to November,the buoys were in the upstream area of the TPD;spatial variations of deformation rates were significantly correlated with initial ice thickness(R=−0.84,P<0.05).From December 2019 to March 2020,the buoys were in the high Arctic and the ice cover was consolidated;heterogeneity in ice kinematics as measured across the buoys reduced by 65%.From April to May 2020,the buoys were in the downstream TPD;amplified spatial variations in ice kinematics were observed.This is because two buoys had drifted over the shallow waters north of Svalbard earlier;trajectory-stretching exponents derived from the data from these two buoys indicate deformation rates(10.6 d^(−1))that were about twice those in the deep basin(4.2 d^(−1)).By June 2020,a less consolidated ice pack and enhanced tidal forcing in the Fram Strait MIZ resulted in ice deformation with a semi-diurnal power spectral density of>0.25 d^(−1),which is about 1.5 times that in PIZ.Therefore,in both the upstream and downstream regions of the TPD,the transition between the MIZ and the PIZ contributes to the spatial and seasonal variations of sea ice motion and deformation.The results from this study can be used to support the characterization of the momentum balance and influencing factors during the ice advection along the TPD,which is a crucial corridor for Arctic sea ice outflow to the north Atlantic Ocean.
文摘The Arctic plays a pivotal role in the Earth’s climate system,with its rapid transformation exerting profound impacts on global climate dynamics,ecosystems,and human societies.In recent decades,Arctic warming has significantly outpaced the global mean temperature increase,driving the enhanced sea ice decline,the accelerated mass loss of the Greenland Ice Sheet,permafrost degradation,and glacier retreat.These changes modulate atmospheric and oceanic circulation patterns,establishing teleconnections with mid-and low-latitude climate systems.Investigating the historical evolution,current state,and projected future trends of the Arctic climate system,as well as its global impacts,is crucial for elucidating the mechanisms underlying Arctic amplification,refining climate change projections,attributing extreme weather and climate events,and informing sustainable development strategies.
