Some recent advances in remote sensing-based monitoring of changes in the Greenland Ice Sheet

The mass balance of the Greenland Ice Sheet(GrIS)plays a crucial role in global sea level change.Since the 1960s,remote sensing missions have been providing extensive and continuous observation data for change monitoring of the GrIS.In this paper,we present our recent research results from remote sensing-based GrIS change monitoring.First,historical satellite data are processed and used to fill data gaps and are combined with existing partial maps,completing an ice velocity map of the GrIS from the 1960s to 1980s.This map provides valuable data for estimating the historical mass balance of Greenland.Second,the monthly gravimetry-based mass balance of the GrIS from 2002 to 2020 is estimated by combining Gravity Recovery and Climate Experiment(GRACE)and GRACE Follow On(GRACE-FO)data.It is found that the GrIS has lost a total mass of approximately 4443±75 Gt during this period.Third,based on Global Land Ice Measurements from Space(GLIMS),an updated Greenland glacier inventory is achieved utilizing data collected between 2006 and 2020.This inventory provides more detailed and up-to-data glacier boundaries of Greenland.Overall,these advances provide essential data support for estimating the mass balance of the GrIS,contributing to the advancement of research on global sea level change.

Sources of Income and Financial Autonomy of Local Self-government

An important feature of local self-government which differs from other public authorities should be the independence of its organs from the government system of administration. The empowerment of local communities, which takes place in all democratic states, has been achieved by giving the guarantee of autonomy to local self-government, including financial autonomy. These are fundamental assumptions of local self-government functioning. The subject of this paper is to present self-government, in the field of shaping the basic sources of public tasks. issues relating to the financial autonomy of loca of its financial supply in cash, enabling the performance

Equality and Self-government For Ethnic Minorities

The Chinese Government has always been keen to promote human rights in the interest of the country's 55 ethnic minority groups, regarding this as vital to promote the country's human rights cause as a whole. Following is an interview with Li Dek Su, an ethnic Korean who serves as minister in charge of the State Ethnic Affairs Commission. We hope that the interview will help give a better idea of the country's policies toward ethnic minorities and the achievements made under such policies.

Analysis of the record-breaking August 2021 rainfall over the Greenland Ice Sheet

Rainfall was witnessed for the first time at the highest area of the Greenland Ice Sheet on 14 August,2021.The thermodynamic mechanisms supporting the rainfall are revealed by ERA5 reanalysis,in-situ and satellite data.We find that a strong southward intrusion of the polar vortex favored the maintenance of a deep cyclone over Baffin Island and an amplification of anticyclonic circulation over the southeastern ice sheet,which pumped warm and moist air toward Greenland from anomalously warm waters south of Greenland.Across a wide swath of the ice sheet,atmospheric uplift maintained above-melting and rainfall conditions via condensation and enhanced downward infrared irradiance.Without the low-level liquid clouds,the spatial extent and duration of the rainfall would have been smaller.Over the ice sheet topographic summit,the air temperature from the ground to 250 hPa level was~2℃higher than the previous record set on 12 July,2012.Such events may occur more frequently with the decreased temperature contrast between the Arctic and the mid-latitude regions that drives highly amplified jet streams.Thus,this extreme event serves as a harbinger of a more likely wet surface condition across all elevations of the ice sheet.

Assessment of Greenland surface melt algorithms based on DMSP and SMOS data

Satellite-borne microwave radiometers provide essential measurements to study the surface melt state of ice sheets. Therefore, selecting suitable microwave radiometer data is critical to characterize the spatial distribution of surface melt. In this study, we investigated the Greenland Ice Sheet and evaluated the usefulness, as climate indicators, of data acquired by microwave radiometers onboard the F17 satellite of the United States of America Defense Meteorological Satellite Program(DMSP) and the Soil Moisture and Ocean Salinity(SMOS) satellite of the European Space Agency. First, surface melt was simulated using the DMSP dataset as input for a brightness temperature threshold algorithm, the Microwave Emission Model of Layered Snowpacks(MEMLS2), and the SMOS dataset as input for the L-band Specific MEMLS(LS-MEMLS). For accuracy evaluation, the simulation results were then compared with surface melt estimates derived from air temperature measurements at Automatic Weather Stations and from ice surface temperature measurements from the Moderate Resolution Imaging Spectroradiometer(MODIS) satellite-borne instrument. Our results show that global(over Greenland) MEMLS2 simulation performance(overall accuracy 83%) was higher than that of LS-MEMLS(overall accuracy 78%). However, in southeastern Greenland, MEMLS2 omission error was markedly higher than that of LS-MEMLS, whereas LS-MEMLS could detect longer-lasting surface melt than MEMLS2. This analysis showed that DMSP-based surface melt simulations are more accurate than SMOS-based simulations, thereby providing a data selection reference for surface melt studies of the Greenland Ice Sheet.

Vibrocorer for undisturbed sampling of firn aquifer layers in Greenland: general concept

The firn aquifer beneath the Greenland Ice Sheet may play a significant role in rising sea level. Both traditional mechanical drilling and electric thermal drilling are poorly adapted for effective, low-disturbance sampling in firn aquifers. We propose using a vibrocoring technique for the undisturbed sampling of dry firn and firn aquifer layers. A remote-controlled vibrocorer is designed to obtain 1-m-long cores with a diameter of 100 mm. The depth capacity of the system is approximately 50 m. The total weight of the vibrocoring system with the surface auxiliary equipment is approximately 110 kg, and corer assembly itself weighs ~60 kg.

Persistently explore new understandings of Greenland Ice Sheet ablation

Greenland and Antarctic ice sheets are the largest potential contributors to global sea level rise(GSLR),amounting to more than 64 m of sea level equivalence(SLE).Between the two,Greenland Ice Sheet(GrIS)alone comprises about 7 mSLE,with a much faster speed of ablation than the Antarctic Ice Sheet.

Performance of surface radiation products of Greenland Ice Sheet using in-situ measurements

Radiation is the direct energy source of the surface natural environment and the main driving force of climate change.It has increasingly become an important meteorological factor affecting the surface heat exchange and glacier mass balance,especially in the glacier changes of the Greenland Ice Sheet(Gr IS).Due to the harsh climatic conditions of Gr IS and sparse observed data,it has become an important way to obtain radiation data from reanalysis datasets.However,the applicability of these radiation data on Gr IS is uncertain and worth exploring.In this work,we evaluate five reanalysis datasets(the fifth generation of European Centre for Medium-Range Weather Forecasts(ERA5),European Centre for Medium-Range Weather Forecasts Interim Reanalysis(ERA-Interim),Japanese 55-year Reanalysis(JRA55),National Centers for Environmental Prediction Reanalysis II(NCEP2)and Modern-Era Retrospective analysis for Research and Applications,Version 2(MERRA-2))during 1997-2022 using observations from 26 Program for Monitoring the Greenland Ice Sheet(PROMICE)automatic weather stations(AWSs)and 3 K-transect AWSs on Gr IS.The conclusions are as follows:ERA5 has the best performances in downward shortwave radiation(SWD)as well as downward and upward longwave radiation(LWD and LWU),but the performance is not the best in upward shortwave radiation(SWU).Based on the radiation budget analysis with ERA5 during 1979-2022,the fluctuation of longwave radiation is greater than that of shortwave radiation.The seasonal variation of shortwave radiation is obvious,while that of longwave radiation is small.The increasing trend of longwave radiation may result from global warming,in which ice sheets absorb more solar radiation and the surface heats up significantly,emitting more LWU.

多模式组合的居住区绿地对热环境影响的模拟研究

居住区作为城镇居民三生活动最主要的空间单元,其热环境质量直接决定了小区内居民的舒适感和幸福度.本文在归纳总结城镇居住区绿地组合模式的基础上,基于非静力流体力学技术和热力学原理,耦合有限差分及交替方向隐式算法对小区范围内不同模式结构组合的绿地生态系统进行热效应模拟研究,通过对比分析不同模式组合的绿地系统热环境效应特征,探寻多模式组合下的居住区绿地与局地热环境间的交互关系.结果表明:在相同的模拟条件下,“中心+宅间”绿地组合模式的热环境效应最好,“组团+宅间”模式次之,“宅间”模式热环境效应最差;模拟区域内三种绿地组合模式的最高最低温度差分别为2.36、2.31和2.34℃,且温度自西南向东北方呈现圈层式分布特征;多绿植类型的组合模式对局地热环境的改善效果依次为:草+灌+乔>草+乔>草+灌>草,灌木对绿地热环境舒适度的改善效果不显著.该研究能够为居住区绿地规划设计与实践提供科学参考.

利用重磁资料研究北极地区格陵兰-冰岛-法罗脊构造特征

为了深入研究北极地区格陵兰-冰岛-法罗脊及邻区的重磁场及构造特征,系统分析与整理了全球重力数据库V29数据、船测重力异常数据、全球地磁异常网格第3版数据以及航空磁测数据。利用变纬度化磁极方法得到磁力化极异常,进而利用位场边缘识别方法进行位场边缘识别,基于滑动平均法计算自由空间重力和磁力化极局部异常。结合已有的研究成果,深入分析格陵兰-冰岛-法罗脊及邻区的区域断裂构造格架,识别了7组主要断裂。这7组断裂在控制隆坳格架、基底结构与性质方面发挥了重要作用。基于这些主要断裂,划分了格陵兰板块、Kolbeinsey脊、扬马延微陆块、东扬马延深海盆地、格陵兰-冰岛-法罗复杂构造带、Rekjanes脊、Aegir脊和法罗-梅恩兰构造带共8个构造单元,为北极地区的地质勘探提供地质及地球物理资料。

基于MCR模型的泉州市绿地生态网络构建与生态节点识别研究

绿地生态网络的构建与生态节点的识别对改善区域生态环境质量和促进物种多样性具有重要的作用。本研究以福建省泉州市为例,对比分析了2010和2020年2个时期的生态源地、生态阻力面变化,探析绿地生态网络时空格局演变。运用形态学空间格局分析(MSPA)、MCR模型和重力模型等方法识别生态源地、构建生态廊道和生态节点,并提出相应的优化策略。结果表明:(1)10年间泉州市生态源地数量由6个增至9个,但生态源地总面积呈现下降趋势。(2)10年间泉州市生态阻力面以各级城镇为高值中心,并以点状和块状向四周扩张。(3)运用MCR模型构建生态廊道24条,其中一级廊道1条,二级廊道10条,三级廊道13条。(4)识别出断裂点993个,生态节点29个。(5)提出保护与增补生态源地、构建与优化生态廊道、建设生态节点与修复生态断裂点三项优化策略。

全格陵兰冰盖表面融水卫星遥感观测

每年夏季,格陵兰冰盖表面消融产生大量融水。冰面融水由冰面河输送,存储在冰面湖或注水冰裂隙中,形成了规模庞大、结构复杂的水文系统。然而,目前研究对全格陵兰冰面融水空间分布的理解十分有限。文章利用134景10 m空间分辨率的Sentinel-2遥感影像,提取了2019年消融旺盛期格陵兰冰面融水遥感信息;进一步,对比分析了遥感观测的冰面融水分布与区域大气气候模型(regional atmospheric climate model,RACMO)模拟的冰面融水径流量。结果表明:①2019年消融旺盛期,格陵兰冰面融水面积为9900.9 km^(2),融水体积为6.8 km^(3);②格陵兰冰面融水的空间分布差异较大,呈现明显的“西多东少”“北多南少”的态势;③格陵兰冰面融水主要由冰面河组成,冰面河占冰面融水总体积的57.1%,其次是注水冰裂隙(25.6%)和冰面湖(17.3%);④RACMO在多数流域准确模拟了冰面融水径流区域。研究反映了高分辨率遥感在格陵兰冰面水文研究中的应用潜力,提升了对冰面融水输送与存储等关键水文过程的理解。

极地冰盖粒雪密实化过程的研究进展

粒雪密实化过程在冰川物质平衡监测和冰芯古气候记录分析等冰川学研究中具有重要作用,近年来国内外学者在极地冰盖开展了大量工作并建立出一系列粒雪密实化模型。本文将典型的极地冰盖粒雪密实化模型分为经验模型(包括半经验模型)和物理模型两大类,综合分析和讨论了两类模型的建模机理、发展现状及不足之处。经验模型关注粒雪柱在密实化过程中的宏观演变,利用实测的粒雪深度-密度数据建立密实化速率方程。目前,该类模型主要研究了温度、积累率、融水渗透和再冻结过程对密实化速率的影响。物理模型聚焦于粒雪晶粒在密实化过程中的微观结构变化,利用晶界滑移、幂律蠕变和晶格扩散等物理机制解释晶粒的生长变形过程。目前,新雪-粒雪转化过程的研究主要基于晶界滑移理论,粒雪-冰川冰转化过程的研究主要基于球形粉末的压力烧结理论。总体而言,极地冰盖粒雪密实化过程的研究在过去几十年取得了长足的发展,但由于粒雪微观结构及其与宏观演变联系的认知匮乏,经验模型缺乏完善的湿粒雪密实化理论,且将稳态假设直接推广到瞬态情景存在一定问题;物理模型由于粒雪密实化的物理机制尚不明确,难以精确刻画粒雪演变的整个物理过程。

中国参与格陵兰国际能源合作的前景探析

在全球气候变暖的背景下,格陵兰岛因其丰富的能源资源,成为外界关注的能源“热土”,也为中国参与格陵兰国际能源合作提供了机遇。格陵兰的石油、铀矿等不可再生能源储量丰富,水能、风能等可再生能源开发潜力巨大,太阳能、地热能也具有一定的应用场景,但开发程度普遍较低。格陵兰能源消费的多元化程度低,清洁能源发展水平有限,石油占据了主要部分,且石油产品全部依赖进口。格陵兰自身的能力十分有限,导致丰富的能源资源不能得到有效利用。格陵兰地方政府与丹麦中央政府的双层博弈,也影响了格陵兰的对外能源合作。美国在北大西洋地区的地缘政治影响力,对包括中国在内的不同开发主体参与格陵兰国际能源合作亦增添了障碍。中国已经在人文交流、基础设施建设、矿产开发等领域与格陵兰进行了一定的合作尝试。未来需要在气候变化乃至全球治理的视野下,关注地缘政治不同方面的利益诉求,树立全球治理理念,重点从清洁能源角度切入格陵兰能源领域的国际合作。

基于卫星重力和测高数据的格陵兰冰盖质量变化分析

格陵兰冰盖全部融化将导致全球海平面上升7m,因此准确估计格陵兰冰盖质量变化过程对理解其对全球气候变化响应和反馈作用具有重要意义。基于Gravity Recovery and Climate Experiment(GRACE)卫星及后继卫星GRACE-FollowOn(GRACE-FO)提供的近20年的月时变重力场数据,以及EuropeanRemote Sensing(ERS-2)、Envisat和CryoSat-2等卫星测高数据,本文对比分析了2002年4月-2020年12月格陵兰冰盖质量变化特征。研究结果表明:(1)卫星重力点质量模型与卫星测高产品估计的质量变化趋势空间分布较为一致,均表明格陵兰冰盖边缘低海拔区域质量亏损严重而内部高原存在质量累积。(2) 2002-2020年格陵兰质量损失对全球平均海平面变化贡献为0.73±0.01mm·a^(-1)。(3)格陵兰冰盖西南部和西北部对海平面变化的贡献占格陵兰总贡献量的43.69%,为主要的海平面上升贡献区。(4)格陵兰冰盖流域尺度的分析表明,Goddard Space Flight Center(GSFC)点质量模型与卫星测高估计的结果更为一致。

不同类型ENSO事件对初冬北极海冰的影响

基于1951—2019年NCEP/NCAR再分析资料、Hadley环流中心海温、海冰密集度资料,通过合成分析和诊断温度异常方程,研究不同类型ENSO对初冬北极海冰的影响。结果表明,EP La Niña发展年初冬(11—12月),巴伦支—喀拉海海冰异常减少;CP La Niña发展初冬,巴伦支—喀拉海海冰异常增加。EP和CP型El Ni1o对初冬北极海冰的影响类似:格陵兰海海冰异常减少,而哈德逊—巴芬湾海冰异常增加。不同类型ENSO对初冬北极海冰的影响主要通过产生不同的大气遥相关,引起同期和前期的海表气温异常而实现。

Accumulation over the Greenland Ice Sheet as Represented in Reanalysis Data

Annual precipitation,evaporation,and calculated accumulation from reanalysis model outputs have been investigated for the Greenland Ice Sheet （GrIS）,based on the common period of 1989-2001.The ERA-40 and ERA-interim reanalysis data showed better agreement with observations than do NCEP-1 and NCEP-2 reanalyses.Further,ERA-interim showed the closest spatial distribution of accumulation to the observation.Concerning temporal variations,ERA-interim showed the best correlation with precipitation observations at five synoptic stations,and the best correlation with in situ measurements of accumulation at nine ice core sites.The mean annual precipitation averaged over the whole GrIS from ERA-interim （363 mm yr 1） and mean annual accumulation （319 mm yr 1） are very close to the observations.The validation of accumulation calculated from reanalysis data against ice-core measurements suggests that further improvements to reanalysis models are needed.

Greenland Ice Sheet Contribution to Future Global Sea Level Rise based on CMIP5 Models

Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large uncertainties in modeled climate and ice sheet behavior. We used the ice sheet model SICOPOLIS （Simulation COde for POLythermal Ice Sheets） driven by climate projections from 20 models in the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to estimate the GrlS contribution to global SLR. Based on the outputs of the 20 models, it is estimated that the GrIS will contribute 0-16 （0-27） cm to global SLR by 2100 under the Representative Concentration Pathways （RCP） 4.5 （RCP 8.5） scenarios. The projected SLR increases further to 7-22 （7-33） cm with 2~basal sliding included. In response to the results of the multimodel ensemble mean, the ice sheet model projects a global SLR of 3 cm and 7 cm （10 cm and 13 cm with 2~basal sliding） under the RCP 4.5 and RCP 8.5 scenarios, respectively. In addition, our results suggest that the uncertainty in future sea level projection caused by the large spread in climate projections could be reduced with model-evaluation and the selective use of model outputs.

The Relationship between the Wintertime Blocking over Greenland and the Sea Ice Distribution over North Atlantic

The sea-ice concentration in the Northern Hemisphere, 500 hPa height, sea-level pressure and 1000-500 hPa thickness of monthly mean data are examined for the period 1953-1989, with emphasis on the winter season.Relationships between large-scale patterns of atmospheric variability and sea-ice variability are investigated, making use of the correlation method. The analysis is conducted for the Atlantic sectors. In agreement with earlier studies based upon monthly mean data on sea-ice concentration, the strongest sea-ice pattern is composed of a dipole with opposing centers of action in the Davis Straits / Labrador Sea region and the Greenland and Barents Seas. Its temporal variability is strongly coupled to the atmospheric North Atlantic Oscillation (NAO). The relationship between the two patterns is strongest with the atmosphere leading the ocean. The polarity of the NAO is associated with Greenland blocking episodes, during which the influence of the atmosphere is strong enough to temporarily halt the climatological mean advance of the ice edge in some regions and substantially accelerate it in others.The relationships between the fields are indicative of local forcing of sea-ice in most regions, with wind stress and thermodynamic fluxes at the air-sea interface both contributing.

Correlation between sea surface temperature and wind speed in Greenland Sea and their relationships with NAO variability

The North Atlantic Oscillation （NAO） is one of the major causes of many recent changes in the Arctic Ocean. Generally, it is related to wind speed, sea surface temperature （SST）, and sea ice cover. In this study, we analyzed the distributions of and correlations between SST, wind speed, NAO, and sea ice cover from 2003 to 2009 in the Greenland Sea at 10°W to 10°E, 65°N to 80°N. SST reached its peak in July, while wind speed reached its minimum in July. Seasonal variability of SST and wind speed was different for different regions. SST and wind speed mainly had negative correlations. Detailed correlation research was focused on the 75~N to 80~N band. Regression analysis shows that in this band, the variation of SST lagged three months behind that of wind speed Ice cover and NAO had a positive correlation, and the correlation coefficient between ice cover and NAO in the year 2007 was 0.61 SST and NAO also had a positive correlation, and SST influenced NAO one month in advance. The correlation coefficients between SST and NAO reached 0.944 for the year 2005, 0.7 for the year 2008, and 0.74 for the year 2009 after shifting SST one month later. NAO also had a positive correlation with wind speed, and it also influenced wind speed one month in advance. The correlation coefficients between NAO and wind speed reached 0.783, 0.813, and 0.818 for the years 2004, 2005, and 2008, respectively, after shifting wind speed one month earlier.