Variation of sea ice and perspectives of the Northwest Passage in the Arctic Ocean

The continued warming of the Arctic atmosphere and ocean has led to a record retreat of sea ice in the last decades.This retreat has increased the probability of the opening of the Arctic Passages in the near future.The Northwest Passage(NWP)is the most direct shipping route between the Atlantic and Pacific Oceans,producing notable economic benefits.Decadal variations of sea ice and its influencing factors from a high-resolution unstructured-grid finite-volume community ocean model were investigated along the NWP in 1988-2016,and the accessibility of the NWP was assessed under shared socioeconomic pathways(SSP245 and 585)and two vessel classes with the Arctic transportation acces-sibility model in 2021-2050.Sea ice thickness has decreased with increasing seawater temperature and salinity,especially within the Canadian Arctic Archipelago(CAA)in 1988-2016,which has facilitated the opening of the NWP.Complete ship navigation is projected to be possible for polar class 6 ships in August-December in 2021-2025,after when it may extends to July under SSP585 in 2026-2030,while open water ships will not be able to pass through the NWP until September in mid-21st century.The navigability of the NWP is mainly affected by the ice within the CAA.For the accessibility of the Parry Channel,the west part is worse than that of the eastern part,especially in the Viscount-Melville Sound.

Changes in sea ice kinematics in the Arctic outflow region and their associations with Arctic Northeast Passage accessibility

Amplification of climate warming in the Arctic is causing a dramatic retreat of sea ice, which means the Arctic sea routes are becoming increasingly accessible. This study used a satellite-derived sea ice motion product to quantify the kinematic features of sea ice in the Arctic outflow region which specially referred to the Fram Strait and to the north of the Northeast Passage(NEP). An observed trend of increased southward sea ice displacement from the central Arctic to the Fram Strait indicated enhancement of the Transpolar Drift Stream(TDS). In the regions to the north of the NEP, the long-term trend of northward sea ice speed in the Kara sector was +0.04 cm/s per year in spring. A significant statistical relationship was found between the NEP open period and the northward speed of the sea ice to the north of the NEP. The offshore advection of sea ice could account for the opening of sea routes by 33% and 15% in the Kara and Laptev sectors, respectively. The difference in sea level pressure across the TDS,i.e., the Central Arctic Index(CAI), presented more significant correlation than for the Arctic atmospheric Dipole Anomaly index with the open period of the NEP, and the CAI could explain the southward displacement of sea ice toward the Fram Strait by more than 45%. The impact from the summer positive CAI reinforces the thinning and mechanical weakening of the sea ice in the NEP region, which improves the navigability of the NEP.

Seasonal changes in sea ice conditions along the Northeast Passage in 2007 and 2012

Remote sensing data from passive microwave and satellite-based altimeters, associated with the data measured underway, were used to characterize seasonal and spatial changes in sea ice conditions along the Arctic Northeast Passage （NEP） and the high-latitude sea route （HSR） north of the island groups in the eastern Arctic Ocean in 2007 and 2012. In both years, summer Arctic sea ice extent reached minima since satellite records began in 1979. However, there were large differences in spatial distribution of sea ice between the two years. Sea ice conditions in the eastern sections of the sea routes were relatively slight in the 2007 summer, because of the remarkable decline of sea ice in the Pacific sector. A belt of sea ice that blocked sections from the western Laptev Sea to the eastern Kara Sea resulted in both sea routes not completely opening through the 2007 summer. The combination of a great storm in early August causing sea ice to be sheared from the Arctic pack ice and the thick ice surviving the winter delayed the summer opening of the eastern parts of the sea routes in 2012. However, the average open period, defined by 50% ice concentration for the entire NEP and HSR, reached 82 d and 55 d, respectively. Thus, 2012 was the most accessible year since the satellite era began in 1979. The distinct decrease in sea ice in the western parts of the HSR in the 2012 summer can be attributed to the thinning preconditions of sea ice prior to the melt season. The HSR opening can benefit Arctic shipping of deeper-draft vessels.

Impacts of 1.5℃ global warming on hydrological conditions of navigation along the Northern Sea Route and Northwest Passage

Arctic navigability is crucial to the global economy and landscape,while there is an omission in understanding how Arctic navigability changes as a function of 1.5℃ of the Paris Agreement.This study investigated the impact of 1.5℃ global warming above the preindustrial level on sea ice conditions and accessibility of the Northern Sea Route(NSR)and Northwest Passage(NWP)with the Polar Operational Limit Assessment Risk Indexing System and new risk demarcation criteria.The Arctic is colder on the Canadian side than on the European side under 1.5℃ warming.Sea ice is mostly less than three years old,and the younger,thinner and less concentrated ice is mainly in the seas along the NSR.Ships above Polar Class(PC)6 might be unimpeded along two passages all the year.Besides,the NSR and NWP have great potential for PC6 ships in October-December,while it is only the NSR for PC7 ships.Caution is still required when navigating the western East Siberian Sea,its surrounding straits,and the Parry Channel.These changes in hydrological conditions are important for global shipping,and this work is helpful for supporting coordinated international decision-making.

Analysis of sea ice conditions and navigability in the Arctic Northeast Passage during the summer from 2002-2021

The decreasing of Arctic sea ice is projected to continue with global warming,which makes the summer navigation conditions of the Arctic improve.Based on the multi-source remote-sensing data with inter-sensor calibration processing and the ship-based observational data from R/V Xuelong and M/V Yongsheng,the sea ice conditions of the Arctic Northeast Passage(NEP)during the 2002-2021 summer seasons were analyzed,and the navigability of the NEP between July and October from 2002 to 2021 was discussed.Inter-sensor calibration could effectively reduce the deviation from different passive microwave data.Sea ice extent and thickness in the NEP decreased annually,which resulted in the navigability of the NEP showing a potential tendency toward improvement in navigability.The navigation period was mainly concentrated in early August to early October.The middle part of the NEP was primarily affected by sea ice.This influence decreased over time,while the navigation period increased,especially in the Vilkitsky Strait,which is a key shipping area.This analysis of sea ice conditions and navigability in the past 20 years could provide a reference for future scientific investigations and aid in merchant ship navigation in the Arctic summer.

Arctic sea ice variation in the Northwest Passage in 1979-2017 and its response to surface thermodynamics factors

Sea ice conditions in the Canadian Arctic Archipelago(CAA)play a key role in the navigation of the Northwest Passage(NWP).Limited by observed sea ice thickness data,the research of temporal and spatial variation of sea ice in the NWP is insufficient.Based on the observed sea ice concentration and simulated thickness data,the temporal and spatial characteristics of sea ice concentration,extent and thickness from 1979 to 2017 in the NWP of the CAA were studied.The more specific pathways of the northern and southern routes of the NWP were evaluated.Against the background of the rapid retreat of Arctic sea ice,the 39-year observed sea ice concentration and extent of the NWP exhibited a relatively large decreasing trend in summer and fall,while heavy sea ice conditions were maintained in winter and spring,with slightly increasing trend in some subregions.The sea ice thickness in most subregions of the NWP showed a decreasing trend,with exception of Lancaster Sound.The sea ice thickness was larger along the northern route than the southern routes.The significant correlation(p<0.05)between sea ice and surface air temperature(SAT)and sea surface temperature(SST)in the NWP suggested that the surface thermodynamic factors had a greater impact on sea ice in the summer and fall,and the variations of sea ice concentration were more closely correlated with the surface thermodynamic factors than sea ice thickness.The SST had a higher correlation with sea ice concentration than SAT,while SAT exhibited a higher correlation with sea ice thickness than SST.The remaining sea ice concentration and thickness in the fall,associated with the summer and fall SAT and SST,contributed to the formation of sea ice in the following winter and spring.The heat content and mixed layer depth were also be considered as the vertical thermodynamic factors to the sea ice condition in the NWP.

Accessibility in key areas of the Arctic in the 21st mid-century

The navigation potential of the Arctic has improved with the rapid retreat of sea ice under continuous warming.The comprehensive evaluation of Arctic accessibility for low ice-breaking ships(civil use)in the mid-century is important to support coordinated international decision-making.In this study,the hydrological conditions and navigation potential in key areas and crucial straits along the Northern Sea Route(NSR)and Northwest Passage(NWP)were assessed under Shared Socioeconomic Pathways(SSPs)using the Polar Operational Limit Assessment Risk Indexing System.The results showed that the most critical areas for navigation in the mid-century(2046-2055)are the waters around the New Siberian Islands and within the Parry Channel.Arctic navigability improves from SSP1-2.6 to SSP2-4.5 to SSP5-8.5,and the accessibility for PC7 ships under SSP2-4.5 is even better for OW ships under SSP5-8.5.The route on the north side of the New Siberian Islands is a relatively good choice within the NSR,and the southern route has a better navigation potential than the Parry Channel within the NWP.In addition,the accessibility of the Dmitri Laptev Strait is better than that of the Sannikov Strait at a monthly scale,although the latter has more navigable days.However,there is little difference in accessibility between the eastern and western parts of the Parry Channel.The best nav-igation potential through the above straits is in September for ordinary ships,and the optimal time window is delayed and extended for PC7 ships.The results can serve as references for policy-making and navigation planning in the Arctic.

A ship navigation information service system for the Arctic Northeast Passage using 3D GIS based on big Earth data

Research on Arctic passages has mainly focused on navigation policies,sea ice extraction models,and navigation of Arctic sea routes.It is difficult to quantitatively address the specific problems encountered by ships sailing in the Arctic in real time through traditional manual approaches.Additionally,existing sea ice information service systems focus on data sharing and lack online calculation and analysis capabil-ities,making it difficult for decision-makers to derive valuable informa-tion from massive amounts of data.To improve navigation analysis through intelligent information service,we built an advanced Ship Navigation Information Service System(SNISS)using a 3D geographic information system(GIS)based on big Earth data.The SNISS includes two main features:(1)heuristic algorithms were developed to identify the optimal navigation route of the Arctic Northeast Passage(NEP)from a macroscale perspective for the past 10 years to the next 100 years,and(2)for key sea straits along the NEP,online local seaice images can be retrieved to provide a fully automatic sea ice data processing workflow,solving the problems of poor flexibility and low availability of real sea ice remote sensing data extraction.This work can potentially enhance the safety of shipping navigation along the NEP.

北极航道短波组网通信效应及极区粒子沉降对其影响的研究

北极航道是指穿过北冰洋,连接大西洋和太平洋的海上航道,北极航道的快速发展对世界政治经济格局将产生深远影响。现有极区单台站短波通信易受极区恶劣空间环境因素的影响,可通率不高,无法对北极航道船舶的安全航行提供可靠保障。本文针对北极航道短波通信保障需求,搭建基于确定性模型的短波通信覆盖区评估理论框架,探究复折射指数射线追踪功率计算方法,进而评估北极航道短波组网通信效应,同时开展了高能粒子沉降等极区电离层扰动对北极航道短波传播效应影响的研究,旨在为短波组网北极航道通信效能评估与站网规划设计提供理论基础。

北极海冰对中国西北地区东部主汛期7月降水分布型的可能影响

选取1961-2020年中国西北地区东部154个气象站7月降水、NCEP/NCAR大气再分析及北极海冰资料,利用SVD分解等统计诊断方法,分析了北极关键区海冰对西北地区东部主汛期7月降水主要模态分布型的可能影响途径。结果表明:影响西北地区东部7月降水异常分布型主要有两种海冰模态,一种是当巴伦支海、千岛群岛海域海冰密集度偏小(大),戴维斯海峡海冰密集度偏大(小)时,激发从戴维斯海峡向东南以及从鄂霍次克海向西南方向传播的波列,使得我国西北地区东部上空500 hPa位势高度场距平为“西高东低”(“西低东高”)的分布,造成区域降水异常为“一致偏少(多)”分布型;另一种当波弗特海东海域海冰密集度偏小时,激发从里海东传至鄂霍次克海的波列以及配合我国华南上空的正位势高度异常,使得冷空气路径偏东、偏南以及西太平洋副热带高压偏强,造成研究区降水异常为“北少南多”分布型,反之为“北多南少”分布型。利用“SVD投影法”建立的海冰关键区因子预测模型,其对西北地区东部主汛期7月的降水距平符号的把握及空间分布型具有一定的预测能力,尤其对“区域一致少型”和“北多南少型”的预测效果较好。

Rossby波传播特征及其对北极东北航道起始段海域天气的影响研究

北极东北航道起始段海域位于我国黄渤海,大风和强降水是可能威胁到该海域航运安全的主要灾害性天气类型。其中寒潮天气过程伴随的冷空气大风以及热带气旋、温带气旋等天气系统产生的大风、强降水等灾害性天气,对该海域航运安全造成很大影响。利用1991—2020年美国国家环境预报中心(National Centers for Environmental Prediction,NCEP)全球逐日再分析资料,分析了北极东北航道适航期(7—10月)Rossby波沿高空急流能量传播特征及其对北极东北航道起始段海域天气的影响,特别是对强降水的影响。结果表明:(1)沿北半球副热带地区250hPa高空西风急流轴经向风表现为纬向三波型准静止的Rossby波形态;(2)高空250hPa大气准静止Rossby波波源位于地中海地区,波动在此激发并沿急流向东传播,传播过程中波动能量耗散,但波源即地中海地区能量的不断注入,使其得以维持和加强;(3)波作用通量散度指数与北极东北航道起始段海域降水量、风速相关系数绝对值达0.5以上,其中位于我国东北部至鄂霍茨克海地区的波作用通量指数与降水量和风速相关系数的绝对值均接近0.9,属于强相关,说明Rossby波沿高空急流传播时能量汇集、加强,对北极东北航道起始段海域的降水量、风速影响较大,从而可触发强降水、大风等灾害性天气;(4)当Rossby波扰动偏强时,向下游传播能量偏强,则西风急流加强,垂直上升运动增强,导致北极东北航道起始段海域降水异常偏多。

中国商船通行北极东北航道现状及其经济效益分析

随着“北极放大”效应的扩大,北极东北航道的通航窗口期逐渐拉长,其夏季常态化运营实现了现实可能性。文章从中国商船航行北极东北航道的实际航行数据出发,分析船只数和航次数、冰级和船型分布、货运量和货物种类、运输航线分布,以及通航窗口期及破冰引航情况,并基于航行数据计算商船航行北极东北航道的航运利润,进行航运经济效益分析。结果表明,中国商船通行北极东北航道的航次数和货运量都处于相对较低的水平,但从总趋势上来看,中国商船通行北极东北航道的航次数在逐年增加,货运量也在不断提高;随着北极海冰的加速消融,中国商船通行北极东北航道的通航窗口期在不断延长,从而使北极东北航道实现常态化商业运营的可能性大大提高;当前中国商船通航北极东北航道的航次数以及运输的货运量较少且通航的窗口期也较短。

基于Sentinel-1卫星数据的北极西北航道通航适宜性分析

北极西北航道对北极资源开发与世界贸易格局有重要影响。针对当前西北航道通航适宜性时空变化分析研究中时空分辨率低、时效性差等问题,利用2015—2019年每年9月及2019年8月1日至9月20日的Sentinel-1 SAR数据,基于k均值非监督分类方法反演了十米级高空间分辨率海冰密集度。通过长时序宏观跟踪和短时序精细分析西北航道全线通航窗口,并以70%的海冰密集度作为阈值,测算了西北航道经过重要海湾及海峡累计不可通航的次数。结果表明:西北航道的航情随冰情而变,通航能力尚不稳定。具体来说,西北航道的冰情呈现东轻西重、南轻北重的格局,不可通航节点个数东少西多、南少北多。2018年9月西北航道通航情况最差,高于可通航阈值的海冰覆盖面积占总航道面积的35.24%,共有10个不可通航节点。2016年和2019年9月的通航情况较好,阿蒙森湾—科罗内申湾—毛德皇后湾—维多利亚海峡—富兰克林海峡—皮尔海峡—巴罗海峡—兰开斯特海峡段航道(航道C)可实现全线通航。进一步通过小尺度时间窗口研究发现,西北航道的最佳通航窗口为8月下旬至9月上旬,期间共出现3条全线通航的航道;最佳通航路线为航道C,其连续通航时间长达30天。

Sea ice conditions and navigability through the Northeast Passage in the past 40 years based on remote-sensing data

Sea ice conditions and navigability along four typical routes of the Northeast Passage(NEP)are analysed using remote-sensing data from 1979 to 2019.The influence of air temperature(T_(air))and surface wind on the sea ice concentration(SIC)and the navigability of routes is determined.It is found that the annually averaged SICs of the different routes have decreased over the past 41 years.The fastest rate of decrease occurred in the Kara Sea(∼−1%per year),while the slowest rates of decrease occurred in the Laptev/East Siberian Sea(∼−0.42%per year).The number of navigable days for the Kara Sea has become∼1–2 months longer than the Laptev/East Siberian Sea route as a result.The effect of T_(air) on SIC,quantified byΔSIC/ΔT_(air) in the routes through the eastern Kara Sea and Laptev/East Siberian Sea in 2010s was∼−0.04/℃,two to three times that seen during the 1980s.Air temperature is becoming a significant driving force of melting ice in these routes.Surface winds are also a crucial factor for the navigability of the Vilkitsky Strait and Long Strait,as they drive ice drift,and affect the navigability of the Kara Strait by introducing warm air.

西北航道夏季气旋登陆期间海冰对波浪的影响

西北航道是指从北大西洋经加拿大北极群岛进入北冰洋,再进入太平洋的航道,是连接大西洋和太平洋的捷径。为了探讨西北航道通航期极端天气条件下强风及海冰对波浪场的影响机制,建立并验证了考虑海冰影响下的西北航道风浪演化模型,并以2012年8月北极气旋登陆期间为例探讨西北航道通航期波浪特性及波能流密度的时空演化及其对风和海冰的响应。研究结果表明,北极夏季海冰大多分布于西北航道以北海域,而风向大部分集中在SSW(南偏西22.5°)至SW(南偏西45°),西北航道海冰的存在并不会引起有效风区的明显减少,也不会引起无冰海域波能流的明显减小(不超过5%)。但是,当风向变为北向风时,无冰海域波能流减小幅度最多高达62%。最后,综合海冰和波浪要素的时空分布,提出了极端天气条件下西北航道通航期的最佳适航路线,为西北航道的夏季安全通航提供了科学依据。

北极地区核动力船舶航行的法律问题研究

依据《联合国海洋法公约》,外国核动力船舶应享有非歧视性的航行权,但因核事故巨大的生态破坏性,许多沿海国对于外国核动力船舶的通过持保守态度,核动力船舶航行权的实现存在着现实困境。随着核动力船舶航行实践不断发展,核动力船舶航行权边界的不确定性问题逐渐凸显,鉴于对航行权的体系化思考,通过分析沿海国管辖权、相关国际协定与标准,有助于弥补《联合国海洋法公约》的缺陷。相比于其他传统国际航道,北极航道有着特殊的航行秩序,《联合国海洋法公约》第234条赋予了沿海国额外管辖权以监管冰封区域的航行活动,这加剧了北极沿海国对外国核动力船舶的限制。而特别敏感海域、海洋保护区、无核区等制度的发展使得北极核动力船舶的航行面临着尤为复杂的制度形势,关于外国核动力船舶在北极过境的诸多法律问题尚待厘清。

开发“冰上丝绸之路”面临的机遇与挑战

“冰上丝绸之路”是“一带一路”倡议在北极地区的延伸,它连接亚欧北美三大洲,构造了一条比传统航线距离更短、运输更经济的海上航线。“冰上丝绸之路”的建设将会给北极地区的资源开发、环境治理以及北极沿线国家的经济发展带来更多的合作机遇。全球气候变暖、技术进步、沿线国家的合作意愿都为北极航道的开发建设提供了重要机遇。但是,“冰上丝绸之路”的建设也面临诸如主权争端、地缘矛盾、环境制约、传统航道的压力等众多的挑战。中国作为“一带一路”的倡议者和参与者应该团结更多的国家积极参与合作,抓住当下的机遇,采取恰当的方式应对挑战。

当前国际形势下北极航道利用前景及对我国影响

2022年爆发的俄乌冲突是长期以来俄罗斯与以美国领导下的北约之间矛盾激化的结果,对全球大国关系和国际政治格局产生持续重大影响。位于俄北冰洋专属经济区管辖范围内的北方海航道构成现阶段北极航运活动的主体,亦受到当前俄乌局势的严峻冲击。该文在总结地缘政治事件对北极航运普遍性影响的基础上,评估当前国际形势对北极航道经济前景的影响,并提出我国应充分考虑西方制裁和全球经济波动等多方因素,从维护我国能源安全、经济安全和通道安全的角度出发,科学和客观地评估当前北极航运发展面临的风险和挑战。

北极西北航道船舶通航风险分析

北极海冰的融化使得北极西北航道通航成为可能,有必要探讨北极西北航道的安全通航风险控制问题。针对北极西北航道冰情和复杂通航环境下的船舶通航窗口期,本研究采用时间维度上的过程风险评估方法,构建了基于系统动力学的北极西北航道通航风险评估模型,结合北极西北航道6条航线的场景条件,通过2015—2021年7年间风、雾、浪、海冰的月平均变化的数据分析,进行北极西北航道船舶通航过程风险仿真,提出了北极西北航道船舶通航窗口期。仿真结果表明:北极西北航道全年可通航的时间窗口为8月下旬至9月上旬,而选择阿蒙森湾—威尔士亲王海峡—巴罗海峡—巴芬湾和阿蒙森湾—维多利亚海峡—皮尔海峡—巴芬湾两条航线的船舶通航风险相对较低,从发展上看,随着海冰快速融化北极西北航道具有较高的通航潜力。

北极航道贸易潜力的时空分布分析

考虑海冰年际变化对北极航道贸易潜力的影响,用航运时间替代航运距离对贸易引力模型进行拓展,采用“多国模型”量化评估了16个北极航道贸易利益相关国贸易潜力的时空分布趋势。结果表明:(1)航行时间每缩短1%,各国之间进出口贸易总额将提升0.512%,冰况越恶劣,贸易潜力提升越低;(2)时间分布趋势上,1991-2019年各国平均贸易潜力因冰情波动呈现先小幅上升,后小幅下降,再不断上升的趋势,并预计到2050年北极航道完全开通时达到最大;(3)空间分布上,东亚近北极国与西欧近北极国、北极航道沿线国的双边贸易潜力提升较大,最高可提升27.06%,传统航道沿线国贸易潜力提升不明显。