Area Of Greenland Research Articles

On the performance of equiangular mascon solution in GRACE-like missions

Mass concentration (mascon) solutions for GRACE (Gravity Recovery and Climate Experiment) data are widely used in various regional-to-global mass change studies. The current advances in the mascon solution have mainly concentrated on improving the spatial resolution of the solution, enhancing the applied least-squares regularization, and the characterization of the solution errors. Most of the mascon solutions are obtained on the equal-area grid, inducing complexities in creating the grid and its presentation. In this regard, estimation of the mascon solutions on equiangular grids can be appealing. Furthermore, in the equal-area methods, there is no global criterion to determine the size of the mascon areas. The mascon size is usually chosen in a subjective manner which hampers the objective application of different mascon solutions. In view of these challenges, two main questions are addressed in this study: i) what kind of modifications should be made in computation scheme of the mascon solution if equiangular grids are used to account for different areas of the grid patches, and ii) in case of non-equiangular solutions, how to define an objective criterion for the patch sizes based on the resolution of both the observation and the signal of interest. We investigate the performance of the high-resolution mascon-based approach, proposed by Abedini et al. [2021], which uses GRACE-like observations similar to level-1 data for a period of one month over the Greenland region. Two main practical issues are studied on the estimation of the surface density changes as follows. First, we show that for equiangular grids, the area of the patches should be accounted for in the regularization by introducing area-affected weights for the unknown parameters. We investigate the effect of three different area-affected weighting strategies on the derived solution. Secondly in order to obtain proper size for the patches, a novel approach is presented to investigate the performance of the mascon solution using the analysis of the resolution matrix entries. The proposed resolution analysis is used to obtain the optimal patch size for the discretization of the area of interest. Based on the results, it is demonstrated that the minimum legible patch size in the Greenland area for the current settings of the GRACE observations is 0.5 degree in the NS direction and a latitude-adaptive grid-size rather than equiangular grids at high latitude regions in the EW direction.

Moisture-dependent Water Repellency of Greenlandic Cultivated Soils

The rapid warming of the Arctic is changing the conditions for agricultural activity in southwest Greenland markedly, which necessitates studies of the physical properties of the soil resource. Soil water repellency (SWR) is a soil property that changes soil functional behaviour across a soil-specific range in water-content (W). Although SWR occurs worldwide, it has not been studied in sub-arctic pasture and grass fields. Thus, the aim was to examine the prevalence of SWR in South Greenland and to establish pedotransfer functions for SWR on soil properties that are faster to measure than SWR, i.e. soil organic fractions, texture and soil water retention. This study included 145 soil samples from 22 sub-arctic agricultural fields distributed across three areas of South Greenland, with broad distributions in texture (clay: 0.017–0.194 kg kg−1) and organic carbon (OC) (0.009–0.241 kg kg−1) contents. The degree of soil water repellency (SWR) as a function of water content (SWR-W curve) was measured from oven-dry conditions to the water-content at which the soil became hydrophilic (WNON), and total SWR (SWRAREA) was calculated as the integrated trapezoidal area (SWRAREA) of the SWR-W curve. A total of 99% and 98% of the soil samples were water-repellent and extremely water repellent at their maximum SWR, respectively. Among the three soil organic fractions (OC, Loss-on-ignition at 550 °C, and 225 °C (LOI550 and LOI225)), LOI550 was the best predictor of SWRAREA and WNON (both with r2 = 0.93). Multiple linear regressions including clay content increased r2adj to 0.92 and 0.95 with OC and LOI550, respectively. The Campbell-Shiozawa (CS) model was fitted to the soil–water retention curves (pF 3.0–6.9), and the inverse slope (−α−1) of the CS model exhibited a high correlation to both SWRAREA (r2adj of 0.87) and WNON (r2adj of 0.93), thus suggesting that soil water retention governs SWR. Lastly, it was shown that the coefficient of proportionality between OC and both SWRAREA and WNON for these sub-arctic soils coincided with pasture soils from New Zealand.

Subpolar Gyre – AMOC – Atmosphere Interactions on Multidecadal Timescales in a Version of the Kiel Climate Model

AbstractThere is a controversy about the nature of multidecadal climate variability in the North Atlantic (NA) region, concerning the roles of ocean circulation and atmosphere-ocean coupling. Here we describe NA multidecadal variability from a version of the Kiel Climate Model, in which both subpolar gyre (SPG)-Atlantic Meridional Overturning Circulation (AMOC) and atmosphere-ocean coupling are essential. The oceanic barotropic and meridional overturning streamfunctions, and sea level pressure are jointly analyzed to derive the leading mode of Atlantic sector variability. This mode accounting for 23.7 % of the total combined variance is oscillatory with an irregular periodicity of 25-50 years and an e-folding time of about a decade. SPG and AMOC mutually influence each other and together provide the delayed negative feedback necessary for maintaining the oscillation. An anomalously strong SPG, for example, drives higher surface salinity and density in the NA’s sinking region. In response, oceanic deep convection and AMOC intensify, which, with a time delay of about a decade, reduces SPG strength by enhancing upper-ocean heat content. The weaker gyre leads to lower surface salinity and density in the sinking region, which reduces deep convection and eventually AMOC strength. There is a positive ocean-atmosphere feedback between the sea surface temperature and low-level atmospheric circulation over the Southern Greenland area, with related wind stress changes reinforcing SPG changes, thereby maintaining the (damped) multidecadal oscillation against dissipation. Stochastic surface heat-flux forcing associated with the North Atlantic Oscillation drives the eigenmode.

Firn Evolution at Camp Century, Greenland: 1966–2100

Camp Century is an American military base built in 1959 under the surface of the Greenland ice sheet and decommissioned in 1967. Here, we use outputs from RACMO2.3p2 and CanESM2 climate models, adjusted to meteorological observations, and a firn model to simulate the firn density and temperature at Camp Century between 1966 and 2100. The model output is evaluated against an extensive set of firn 3observations and three Representative Concentration Pathways (RCP2.6, 4.5 and 8.5) are considered as future scenarios. Our model suggests that the upper horizon of the Camp Century debris field – observed at a depth of 32 m in 2017 – will continue to be buried by persistent net accumulation over the next eighty years under all RCP scenarios. This horizon depth will be between 58 and 64 m in 2100, depending on the RCP scenario. We estimate a maximum meltwater percolation depth of 1.1 m under all RCP scenarios. We therefore find it extremely unlikely that surface meltwater interacts with the subsurface debris field at Camp Century before 2100 under all RCP scenarios. Camp Century’s future is representative of the firn area in northwestern Greenland, bound to shift from dry snow to a percolation regime. Our model suggests that 10 m firn temperatures at Camp Century will increase from −24.0°C in 1966 to −21.3, −20.0 and −18.6°C in 2100 under the RCP2.6, 4.5 and 8.5 scenarios, respectively. We reveal a previously unknown warm bias in air temperatures simulated at Camp Century by both RACMO2.3p2 and CanESM2 climate models which needs to be accounted for when using these models to predict melt, firn evolution and sea-level contribution of the Greenland ice sheet. We also present novelin situmeasurements of firn compaction rates, which indicate that about 25% of firn compaction of the top 62 m of firn occurs below 20 m depth. This highlights the importance of deep-firn compaction measurements for model evaluation and correction of altimetry products.

The application of land use regression model to investigate spatiotemporal variations of PM2.5 in Guangzhou, China: Implications for the public health benefits of PM2.5 reduction.

Understanding the intra-city variation of PM2.5 is important for air quality management and exposure assessment. In this study, to investigate the spatiotemporal variation of PM2.5 in Guangzhou, we developed land use regression (LUR) models using data from 49 routine air quality monitoring stations. The R2, adjust R2 and 10-fold cross validation R2 for the annual PM2.5 LUR model were 0.78, 0.72 and 0.66, respectively, indicating the robustness of the model. In all the LUR models, traffic variables (e.g., length of main road and the distance to nearest ancillary) were the most common variables in the LUR models, suggesting vehicle emission was the most important contributor to PM2.5 and controlling vehicle emissions would be an effective way to reduce PM2.5. The predicted PM2.5 exhibited significant variations with different land uses, with the highest value for impervious surfaces, followed by green land, cropland, forest and water areas. Guangzhou as the third largest city that PM2.5 concentration has achieved CAAQS Grade II guideline in China, it represents a useful case study city to examine the health and economic benefits of further reduction of PM2.5 to the lower concentration ranges. So, the health and economic benefits of reducing PM2.5 in Guangzhou was further estimated using the BenMAP model, based on the annual PM2.5 concentration predicted by the LUR model. The results showed that the avoided all cause mortalities were 992 cases (95% CI: 221-2140) and the corresponding economic benefits were 1478 million CNY (95% CI: 257-2524) (willingness to pay approach) if the annual PM2.5 concentration can be reduced to the annual CAAQS Grade I guideline value of 15μg/m3. Our results are expected to provide valuable information for further air pollution control strategies in China.

Estimation of surface density changes using a mascon method in GRACE-like missions

Gravity Recovery and Climate Experiment (GRACE) data are a valuable source of information for estimating hydrological mass changes. Several approaches have been conducted to investigate surface density changes from satellite-based observations. The traditional approaches are mainly based on the Stokes coefficients, related to a spherical harmonic representation of the gravitational potential. This study aims to develop an alternative method to estimate the temporal variations in water storage. It is based on a specific type of mascon technique that investigates the possibility of obtaining a solution without Stokes coefficients. The method uses a piecewise constant surface density function to estimate surface density changes based on the GRACE satellite-to-satellite tracking (SST) data. The surface density changes are directly obtained from the variations in positions and velocities of the two GRACE satellites. We therefore avoid the series truncation and aim to improve the leakage problem at the price of higher numerical burden. The proposed method is numerically tested on synthetic data similar to level-1 GRACE data for a period of one month. Two regularization methods, the well-known Tikhonov solution and a method that accounts for the areas of different patches, are employed to obtain a stable solution. The accuracy assessment over the Greenland area indicates that the estimated values are reliable and statistically significant, a further confirmation of the efficacy and stability of the method.

Subjective well-being in East Greenland

ABSTRACT This paper analyses subjective well-being (SWB) among inhabitants in East Greenland. Recently, considerable public attention has been directed toward the conditions of East Greenland, particularly in the Ammassalik region. Shocking reports on severe social problems with substance abuse, domestic violence, and child abuse continue to emerge. Meanwhile, the latest studies of SWB show that satisfaction with life is relatively high despite the poor living conditions. This study aims to explore inhabitants’ perceptions of what it means to have a good life, via personal interviews in four locations on the East Greenlandic coast. It discusses specific domains and indicators, such as social relations, emotional well-being, and employment status, and their impact on overall well-being. Finally, the paper discusses whether the findings presented support or dispute existing research practices, with a focus on the report Arctic Social Indicators (ASI) and the Survey of Living Conditions in the Arctic (SLiCA). This study highlights the gap in leading research practice, suggesting that additional research on SWB in Greenland and other areas in the Arctic be conducted to ensure that SWB, as a direct measure, is included in future social indicator research in the Arctic.

Cryoseismologic Studies for Polar Environment—Recent Progress of Japanese Contribution

Majority areas of Antarctica and Greenland are under the thick ice sheet and characterized by evolving cryosphere surroundings. In the polar region, associated with the recent trend on climate change such as global warming, glacier relating earthquakes are increasing during this 21st century. In this paper, a decade of progress in “Cryoseismology” at bi-polar regions is re-viewed by focusing on the contribution from Japanese researchers. In particular, the specific cryoseismic events are treated, which occurred in the coastal area of East Antarctica, around the Lutzow-Holm Bay, together with the coast and whole inland area of Greenland. As the major scientific results, frequency-overtone signals in the harmonic cryoseismic tremors were analyzed by assuming constant sources, suggesting inter-glacial asperities that generate characteristic tremors. Infrasound source locations were also determined by using the array deployment at the coastal regions in the Antarctic. In contrast, characteristics of glacial earthquakes and seismic interferometry approach have been conducted so as to achieve the fine structure of the Greenland Ice Sheet (GrIS) in particular the basal condition beneath the ice sheet.

Integrated renovation practices on water resilient infrastructure in Tainan Taikang elementary school in Taiwan

From 2009 to 2017, there were more and more climate disasters which has caused serious damages in campuses, especially the heavy rain, flooding, debris flow in summer and long-term drought in winter. Therefore, based on the successes of small scaled experiments and solutions, MOE start the demonstration campus project in the year of 2018 to make a holistic solution demo site in typical aspect which can be the liveable learning centre for all. The Taikang elementary school in the countryside of Tainan was selected. Goals were set to fully demonstrate both rainwater and grey water resilience and its enhanced usage in the campus. There are four goals: 1. reduce of use and disaster impact, 2. full water absorption ability of all infrastructures from building to site, 3. bioclimate control by introducing green land and water areas to cool down the campus, and 4. maximized reusability. The campus has been reorganized by introducing a holistic water system with large underground water storage rooms underneath both buildings and playground runways paved with demolished concrete gravels, and a reconnected water circulation system for stormwater management and natural infiltration irrigation. Supported by the participation of community, the total cost of the system was a staggering 200,000 USD. The changes were obvious from the taps to the entire system integrated with environmental education. In comparison to previous situations, the campus can withstand heavy rainfall over 80 mm/hr for three hours without flooding, meanwhile providing more than 90% of all the irrigation water needed to water the green lands the entire year. Moreover, the natural cooling system of green lands and water areas provides a cool breeze for natural ventilated classrooms.

Stephen Moorbath. 9 May 1929 — 16 October 2016

Stephen Moorbath was an intellectual with eclectic interests across the sciences and humanities. In 1939, as a ten-year-old, he fled from Germany to England with his father. Stephen spent almost the whole of the rest of his life—from schoolboy to university professor—in Oxford, where he became one of the world's leading isotope geochemists. His academic career began with setting up Europe's first radiometric rock and mineral dating laboratory. In this laboratory, together with numerous colleagues and students, he applied the lead–lead, rubidium–strontium, potassium–argon and, later, samarium–neodymium isotopic dating methods to the solution of many geological problems. He made major contributions in establishing the chronology for the geological and tectonic evolution of Precambrian crust in the Scottish Highlands and Islands, in West Greenland, Zimbabwe, South India, and Ghana. He developed isotopic criteria for assessing the relative contributions of mantle and crustal sources to Tertiary igneous rocks in Scotland, Andean volcanics and the late Archaean granitoids of West Greenland. He established dating methods for sedimentary rocks: Rb–Sr for shales and Pb/Pb for Archaean limestone. Stephen's abiding geological passion was the study of the early Archaean, especially the Godthåbsfjord and Isukasia areas of West Greenland.

Variations of Mass Balance of the Greenland Ice Sheet from 2002 to 2019

The melting of the polar ice caps is considered to be an essential factor for global sea-level rise and has received significant attention. Quantitative research on ice cap mass changes is critical in global climate change. In this study, GRACE JPL RL06 data under the Mascon scheme based on the dynamic method were used. Greenland, which is highly sensitive to climate change, was selected as the study area. Greenland was divided into six sub-research regions, according to its watersheds. The spatial–temporal mass changes were compared to corresponding temperature and precipitation statistics to analyze the relationship between changes in ice sheet mass and climate change. The results show that: (i) From February 2002 to September 2019, the rate of change in the Greenland Ice Sheet mass was about −263 ± 13 Gt yr−1 and the areas with the most substantial ice sheet loss and climate changes were concentrated in the western and southern parts of Greenland. (ii) The mass balance of the Greenland Ice Sheet during the study period was at a loss, and this was closely related to increasing trends in temperature and precipitation. (iii) In the coastal areas of western and southern Greenland, the rate of mass change has accelerated significantly, mainly because of climate change.

The geology of the Centrumsø area of Kronprins Christian Land, northeast Greenland, and lithological constraints on speleogenesis

The geology of the Centrumsø area of Kronprins Christian Land, northeast Greenland, and lithological constraints on speleogenesis

An Evaluation System for Sustainable Urban Space Development Based in Green Urbanism Principles—A Case Study Based on the Qin-Ba Mountain Area in China

Since the 20th century, the deterioration of the ecological environment around the world has challenged urban space construction. With the development of urbanization, the consumption of resources and energy has increased, the level of biodiversity has decreased, environmental pollution is approaching the critical level, and the contradiction between human habitat activity and ecological environment has become increasingly prominent. The sustainable development of urban space along with its economic and social benefits, taking into account the quality of life and ecological environment, has become a new and important subject that needs to be explored. In this study, the indices of the evaluation system for sustainable urban spatial development in regions with underdeveloped economies but rich in ecological resources are arranged in sequence through the systematic coupling analysis of collaborative evaluation information and a quantitative analysis. The influences of urban space elements on sustainable urban development are disclosed. On the basis of the generated data, an evaluation system for sustainable urban spatial development with a complete set of information is proposed. The proposed system is applicable to urban spatial development evaluation in regions in China with underdeveloped economies but rich in ecological capital. First, the basic concept of system coupling is introduced, and a coupling relationship between urban sustainable development and urban space is proposed. Second, the elements of urban space and the sustainable development in the Qin-Ba mountain area are extracted, and the precedence diagram method is used to construct a sustainable evaluation system for urban space development in the Qin-Ba mountain area. Third, the sustainable evaluation process of urban spatial development is proposed. Finally, the sustainable evaluation system for urban spatial development in the Qin-Ba mountain area is applied to evaluate the urban spatial development in Shangluo, Qin-Ling Mountains, China. The results show that, among the investigated 14 indicators, the proportion of industrial land use mainly influences sustainable urban spatial development. As for the rest of the index factors, per capita green land area and green coverage ratio of built-up areas, per capita urban construction land area, proportion of forestry area, greening rate of built-up areas, total industrial dust emission density, proportion of cultivated area, and average volume fraction of residential areas are the secondary influencing factors of sustainable urban spatial development. The evaluation system in this research is constructed with the three aspects of “green coordination”, “green development”, and “green sustainability” of sustainable urban spatial development, and it complements the evaluation contents of urban–rural ecological space coordination, land resource protection, and green development community, and so on. The conclusion of this study not only can provide a useful reference for urban spatial development planning for underdeveloped ecological capital areas of China but also can provide a theoretical basis for the management and control policy of sustainable urban spatial development.

The Impact of Vegetation on Archaeological Sites in the Low Arctic in Light of Climate Change

Vegetation is changing across the Arctic in response to increasing temperatures, which may influence archaeological sites in the region. At the moment, very little is known about how different plant species influence archaeological remains. In this study we visited 14 archaeological sites stretching across a climatic gradient from the outer coast to the inner fjords in the Nuuk Fjord area of West Greenland to assess the impact of vegetation growth on archaeological preservation. Examination of the physical disturbance of archaeological layers and materials by roots from different plant species showed that horsetail (Equisetum arvense) was particularly destructive because of its deep penetrating rhizomes and ubiquity across the study area. Willow (Salix glauca) also caused physical disturbance due to a dense root network, but its roots were mainly found in the upper 30 cm of the soil. Focus was also given to the impact from vegetation on the visibility of sites, where growth of willow was found be the main problem, especially in the inner fjords. Historic descriptions and aerial photographs from the sites show that shrub growth was already widespread in the region by the 1930s, but photos of some of the sites investigated show that the willow shrubs are significantly taller today, which has decreased the visibility of site features. The impact from horsetail and willow on archaeological sites may be mitigated using geotextiles and grazing by livestock, but both methods require further studies before being implemented in the study area.

New insights on metals in the Arctic aerosol in a climate changing world

Ship traffic, population, infrastructure development, and mining activities are expected to increase in the Arctic due to its rising temperatures. This is expected to produce a major impact on aerosol composition. Metals contained in atmospheric particles are powerful markers and can be extremely helpful to gain insights on the different aerosol sources. This work aims at studying the sources of metals in the Arctic aerosol sampled at the Thule High Arctic Atmospheric Observatory (THAAO; Greenland, 76.5°N 68.8°W).Due to the particular composition of Greenlandic soils and to properties of other sources, it was possible to find several signatures of natural and anthropogenic aerosols transported from local and long-range regions.Arctic haze (AH) at Thule builds up on long-range transported aerosol mainly from Canada and Nord America. From a chemical standpoint, this aerosol is characterized by a high concentration of sulfate, Pb, As and Cd and by a La/Ce ratio larger than 1. The Ti/Al and Fe/Al ratios in the AH aerosol are lower (Ti/Al = 0.04 w/w; Fe/Al = 0.79 w/w) than for local aerosol (Ti/Al = 0.07 w/w; Fe/Al = 0.89 w/w).Conversely, aerosol arising from coastal areas of South-West Greenland is characterized by a high concentration of V, Ni, and Cr. These metals, generally considered anthropogenic, arise here mainly from natural crustal sources. In some summer samples, however, the V/Ni ratio becomes larger than 3. In particular, cases displaying this characteristic ratio, as also shown by backward trajectories, are associated with sporadic transport to Thule of ship aerosol from ships passing through Baffin Bay and arriving to Thule during summer.Although further measurements are necessary to confirm the discussed results, the analysis carried out in this work on a large number of metals sampled in coastal Greenland aerosol is unprecedented.

Icy, Watery, Liquescent

In the coastal areas of Northwest Greenland, water, ice and land intermingle with the lives and trajectories of humans and animals, take on a multitude of shapes and forms, and give rise to a complexity of social relations. However, as in other parts of the Arctic, the effects of climate change are increasingly evident. Sea ice cover during winter and spring is less extensive than people living in the region today have known it to be, while icebergs calve from tidewater glaciers at arate faster than they and scientists have previously observed. Glacial ice mass is diminishing and increased meltwater runoff from glacial fronts affects water temperature, ocean depths and circulation patterns, as well as the formation and thickness of sea ice and the movements of marine mammals and fish. These changes have profound implications for local livelihoods and mobilities, the wider regional economy, and human-animal interactions. In this article, I consider what some of the effects of climate change mean for people and their surroundings in Northwest Greenland’s Upernavik area and draw attention to liquescence as a counter to the “ice is melting” narrative that typically understands climate change as liquification. While the scientific monitoring of sea ice, glacial ice loss, and surface melt on the inland ice in the Upernavik region—and in the wider Northwest Greenland area—is well established, and contributes to the regular updating of state of the ice reports for the Arctic, little attention has been given to what these changes to ice and water mean for people and for human and non-human relational ontologies. Thinking of this in terms of liquescence, rather than liquification is a way of moving toward a deeper appreciation of people’s experiences and sense-making of the changes happening to them and to their surroundings as affective, sensorial and embodied.

Water, ice, and climate change in northwest Greenland

AbstractAlong the coastal areas of northwest Greenland, sea ice is crucial to people's livelihoods. People in the region have long depended on hunting marine mammals such as seals; walrus; narwhal, beluga, fin, and minke whales; and polar bears, as well as fishing for fjord cod, Greenland halibut, salmon, and Arctic char. Terrestrial animals such as reindeer and Arctic foxes have also been of some importance, as have musk ox in some areas. However, the effects of a changing climate on the marine environment are stark, immediate, and tangible. Ice is melting, and coastal waters are warming. Sea ice, glaciers, coastlines, and seas have become sites and objects for new forms of environmental governance shaped by ideas of unique and fragile ecosystems under threat at a moment of planetary crisis. Conservation organizations frame the Arctic as a zone of climate change crisis and have launched campaigns—underpinned by narratives of ruination—to protect what are termed last areas of ice. However, Inuit organizations are also working to ensure that environmental governance and conservation policymaking do not exclude local communities in the region and are campaigning for protected marine areas in which wildlife management systems and community‐based monitoring take note of indigenous rights and incorporate indigenous knowledge.This article is categorized under: Science of Water > Water and Environmental Change Human Water > Rights to Water Human Water > Water Governance Water and Life > Conservation, Management, and Awareness

Constraints from cosmogenic nuclides on the glaciation and erosion history of Dove Bugt, northeast Greenland

AbstractThe intricate interplay between subglacial topography and ice-sheet dynamics is key to the evolution of large ice sheets, but in Greenland as elsewhere the effects of long-term glacial history on landscape evolution remain poorly constrained. Here we measure abundances of cosmogenic 10Be and 26Al in bedrock and transported boulders to unveil the glaciation and erosion history of Dove Bugt, northeast Greenland. In agreement with studies of west Greenland, we find that apparent exposure ages increase with elevation from 9 ka to 13 ka in low-lying valleys to 21 ka to 204 ka on high-elevation, blockfield-covered plateaus. We employ a Markov chain Monte Carlo inversion framework to constrain the probability of various erosion histories, and we quantify the residence time of samples within the upper 2 m of the bedrock subsurface—a measure defined as the cosmogenic nuclide memory. This cosmogenic nuclide memory exceeds 600 ka on the highest plateaus but is limited to less than 500 ka in most other high-elevation samples and to less than 100 ka at low-elevations. Our results define maximum limits for the fraction of ice cover during the past 1 Ma to ∼70% on the Store Koldewey peaks and ∼90% farther inland at Pusterdal, respectively. Minimum limits to ice cover, however, cannot be reliably constrained by the data. Finally, we propose that limited erosion on the highest plateaus of Store Koldewey since 0.6–1.0 Ma indicates a minimum age for fjord-plateau formation within this area of northeast Greenland.

Maker Buoy Variants for Water Level Monitoring and Tracking Drifting Objects in Remote Areas of Greenland.

Meltwater runoff from the Greenland Ice Sheet changes water levels in glacial lakes and can lead to glacial lake outburst flooding (GLOF) events that threaten lives and property. Icebergs produced at Greenland’s marine terminating glaciers drift into Baffin Bay and the North Atlantic, where they can threaten shipping and offshore installations. Thus, monitoring glacial lake water levels and the drift of icebergs can enhance safety and aid in the scientific studies of glacial hydrology and iceberg-ocean interactions. The Maker Buoy was originally designed as a low-cost and open source sensor to monitor surface ocean currents. The open source framework, low-cost components, rugged construction and affordable satellite data transmission capabilities make it easy to customize for environmental monitoring in remote areas and under harsh conditions. Here, we present two such Maker Buoy variants that were developed to monitor water level in an ice-infested glacial lake in southern Greenland and to track drifting icebergs and moorings in the Vaigat Strait (Northwest Greenland). We describe the construction of each design variant, methods to access data in the field without an internet connection, and deployments in Greenland in summer 2019. The successful deployments of each Maker Buoy variant suggest that they may also be useful in operational iceberg management strategies and in GLOF monitoring programs.

Dynamic response of the Greenland ice sheet to recent cooling

The subglacial hydrological system critically controls ice motion at the margins of the Greenland Ice Sheet. However, over multi-annual timescales, the net impact of hydro-dynamic coupling on ice motion remains poorly understood. Here, we present annual ice velocities from 1992–2019 across a ~10,600 km2 land-terminating area of southwest Greenland. From the early-2000s through to ~2012, we observe a slowdown in ice motion in response to increased surface melt, consistent with previous research. From 2013 to 2019 however, we observe an acceleration in ice motion coincident with atmospheric cooling and a ~15% reduction in mean surface melt production relative to 2003–2012. We find that ice velocity speed-up is greater in marginal areas, and is strongly correlated with ice thickness. We hypothesise that under thinner ice, increases in basal water pressure offset a larger proportion of the ice overburden pressure, leading to reduced effective pressure and thus greater acceleration when compared to thicker ice further inland. Our findings indicate that hydro-dynamic coupling provides the major control on changes in ice motion across the ablation zone of land terminating margins of the Greenland Ice Sheet over multi-annual timescales.