Andreas Max Kääb

• Dunn, Robert J. H.; Miller, John B.; Willet, Kate M.; Gobron, Nadine; Ades, Melanie & Adler, Robert [Vis alle 56 forfattere av denne artikkelen] (2023). State of the Climate in 2022: 2. Global Climate. Bulletin of The American Meteorological Society - (BAMS). ISSN 0003-0007. 104(9), s. S11–S145. doi: 10.1175/BAMS-D-23-0090.1.
• Kääb, Andreas & Girod, Luc (2023). Brief communication: Rapid ∼ 335 × 106 m3 bed erosion after detachment of the Sedongpu Glacier (Tibet). The Cryosphere. ISSN 1994-0416. 17(6), s. 2533–2541. doi: 10.5194/tc-17-2533-2023. Fulltekst i vitenarkiv
• Kääb, Andreas; Bazilova, Varvara; Leclercq, Paul; Holmlund, Erik Schytt & Strozzi, Tazio (2023). Global clustering of recent glacier surges from radar backscatter data, 2017-2022. Journal of Glaciology. ISSN 0022-1430. 69(277), s. 1515–1523. doi: 10.1017/jog.2023.35. Fulltekst i vitenarkiv
• Westermann, Sebastian; Ingeman-Nielsen, Thomas; Scheer, Johanna; Aalstad, Kristoffer; Aga, Juditha & Chaudhary, Nitin [Vis alle 24 forfattere av denne artikkelen] (2023). The CryoGrid community model (version 1.0) - a multi-physics toolbox for climate-driven simulations in the terrestrial cryosphere. Geoscientific Model Development. ISSN 1991-959X. 16(9), s. 2607–2647. doi: 10.5194/gmd-16-2607-2023. Fulltekst i vitenarkiv Vis sammendrag

  The CryoGrid community model is a flexible toolbox for simulating the ground thermal regime and the ice–water balance for permafrost and glaciers, extending a well-established suite of permafrost models (CryoGrid 1, 2, and 3). The CryoGrid community model can accommodate a wide variety of application scenarios, which is achieved by fully modular structures through object-oriented programming. Different model components, characterized by their process representations and parameterizations, are realized as classes (i.e., objects) in CryoGrid. Standardized communication protocols between these classes ensure that they can be stacked vertically. For example, the CryoGrid community model features several classes with different complexity for the seasonal snow cover, which can be flexibly combined with a range of classes representing subsurface materials, each with their own set of process representations (e.g., soil with and without water balance, glacier ice). We present the CryoGrid architecture as well as the model physics and defining equations for the different model classes, focusing on one-dimensional model configurations which can also interact with external heat and water reservoirs. We illustrate the wide variety of simulation capabilities for a site on Svalbard, with point-scale permafrost simulations using, e.g., different soil freezing characteristics, drainage regimes, and snow representations, as well as simulations for glacier mass balance and a shallow water body. The CryoGrid community model is not intended as a static model framework but aims to provide developers with a flexible platform for efficient model development. In this study, we document both basic and advanced model functionalities to provide a baseline for the future development of novel cryosphere models.

• Berthier, Etienne; Floriciou, Dana; Gardner, Alex S.; Gourmelen, Noel; Jakob, Livia & Paul, Frank [Vis alle 16 forfattere av denne artikkelen] (2023). Measuring glacier mass changes from space-a review. Reports on progress in physics (Print). ISSN 0034-4885. 86(3). doi: 10.1088/1361-6633/acaf8e. Fulltekst i vitenarkiv
• Dunn, Robert J.H.; Aldred, Freya; Gobron, Nadine; Miller, John B.; Willett, Kate M. & Ades, Melanie [Vis alle 195 forfattere av denne artikkelen] (2022). State of the Climate in 2021: Global Climate . Bulletin of The American Meteorological Society - (BAMS). ISSN 0003-0007. 103(8), s. S11–S142. doi: 10.1175/BAMS-D-22-0092.1.
• Bazilova, Varvara & Kääb, Andreas (2022). Mapping Area Changes of Glacial Lakes Using Stacks of Optical Satellite Images. Remote Sensing. ISSN 2072-4292. 14(23). doi: 10.3390/rs14235973. Fulltekst i vitenarkiv
• Van Wyk De Vries, Maximillian; Bhushan, Shashank; Jacquemart, Mylène; Deschamps-Berger, Cesar; Berthier, Etienne & Gascoin, Simon [Vis alle 9 forfattere av denne artikkelen] (2022). Pre-collapse motion of the February 2021 Chamoli rock-ice avalanche, Indian Himalaya. Natural Hazards and Earth System Sciences. ISSN 1561-8633. 22(10), s. 3309–3327. doi: 10.5194/nhess-22-3309-2022. Fulltekst i vitenarkiv
• Altena, Bas; Kääb, Andreas & Wouters, Bert (2022). Correlation dispersion as a measure to better estimate uncertainty in remotely sensed glacier displacements. The Cryosphere. ISSN 1994-0416. 16(6), s. 2285–2300. doi: 10.5194/tc-16-2285-2022. Fulltekst i vitenarkiv
• Gartner-Roer, Isabelle; Brunner, Nina; Delaloye, Reynald; Haeberli, Wilfried; Kääb, Andreas & Thee, Patrick (2022). Glacier-permafrost relations in a high-mountain environment: 5 decades of kinematic monitoring at the Gruben site, Swiss Alps. The Cryosphere. ISSN 1994-0416. 16, s. 2083–2101. doi: 10.5194/tc-16-2083-2022. Fulltekst i vitenarkiv
• Gilbert, Adrien; Gimbert, Florent; Thøgersen, Kjetil; Schuler, Thomas & Kääb, Andreas (2022). A Consistent Framework for Coupling Basal Friction With Subglacial Hydrology on Hard-Bedded Glaciers. Geophysical Research Letters. ISSN 0094-8276. 49(13). doi: 10.1029/2021GL097507. Fulltekst i vitenarkiv
• Paul, Frank; Piermattei, Livia; Treichler, Désirée; Gilbert, Lin; Girod, Luc & Kääb, Andreas [Vis alle 10 forfattere av denne artikkelen] (2022). Three different glacier surges at a spot: What satellites observe and what not. The Cryosphere. ISSN 1994-0416. 16(6), s. 2505–2526. doi: 10.5194/tc-16-2505-2022. Fulltekst i vitenarkiv Vis sammendrag

  In the Karakoram, dozens of glacier surges occurred in the past two decades, making the region one of its global hot spots. Detailed analyses of dense time series from optical and radar satellite images revealed a wide range of surge behaviour in this region: from slow advances longer than a decade at low flow velocities to short, pulse-like advances over one or two years with high velocities. In this study, we present an analysis of three currently surging glaciers in the central Karakoram: North and South Chongtar Glaciers and an unnamed glacier referred to as NN9. All three glaciers flow towards the same region but differ strongly in surge behaviour. A full suite of satellite sensors and digital elevation models (DEMs) from different sources are used to (a) obtain comprehensive information about the evolution of the surges from 2000 to 2021 and (b) to compare and evaluate capabilities and limitations of the different satellite sensors for monitoring relatively small glaciers in steep terrain. A strongly contrasting evolution of advance rates and flow velocities is found, though the elevation change pattern is more similar. For example, South Chongtar Glacier had short-lived advance rates above 10 km y−1, velocities up to 30 m d−1 and surface elevations increased by 200 m. In contrast, the neighbouring and three times smaller North Chongtar Glacier had a slow and near linear increase of advance rates (up to 500 m y−1), flow velocities below 1 m d−1 and elevation increases up to 100 m. The even smaller glacier NN9 changed from a slow advance to a full surge within a year, reaching advance rates higher than 1 km y−1. It seems that, despite a similar climatic setting, different surge mechanisms are at play and a transition from one mechanism to another can occur during a single surge. The sensor inter-comparison revealed a high agreement across sensors for deriving flow velocities, but limitations are found on small and narrow glaciers in steep terrain, in particular for Sentinel-1. All investigated DEMs have the required accuracy to clearly show the volume changes during the surges and elevations from ICESat-2 ATL06 data fit neatly. We conclude that the available satellite data allow for a comprehensive observation of glacier surges from space when combining different sensors to determine the temporal evolution of length, elevation and velocity changes.

• Altena, Bas & Kääb, Andreas (2021). Quantifying river ice movement through a combination of European satellite monitoring services. International Journal of Applied Earth Observation and Geoinformation. ISSN 1569-8432. 98. doi: 10.1016/j.jag.2021.102315. Fulltekst i vitenarkiv
• How, Penelope; Messerli, Alexandra; Mätzler, Eva; Santoro, Maurizio; Wiesmann, Andreas & Caduff, Rafael [Vis alle 11 forfattere av denne artikkelen] (2021). Greenland-wide inventory of ice marginal lakes using a multi-method approach. Scientific Reports. ISSN 2045-2322. 11. doi: 10.1038/s41598-021-83509-1. Fulltekst i vitenarkiv
• Shugar, D.H.; Jacquemart, M.; Shean, D.; Bhushan, S.; Upadhyay, K. & Sattar, A. [Vis alle 53 forfattere av denne artikkelen] (2021). A massive rock and ice avalanche caused the 2021 disaster at Chamoli, Indian Himalaya. Science. ISSN 0036-8075. 373(6552), s. 300–306. doi: 10.1126/science.abh4455.
• Leclercq, Paul; Kääb, Andreas & Altena, Bas (2021). Brief communication: Detection of glacier surge activity using cloud computing of Sentinel-1 radar data. The Cryosphere. ISSN 1994-0416. 15(10), s. 4901–4907. doi: 10.5194/tc-15-4901-2021.
• Kääb, Andreas; Jacquemart, Mylene; Gilbert, Adrien; Leinss, Silvan; Girod, Luc & Huggel, Christian [Vis alle 15 forfattere av denne artikkelen] (2021). Sudden large-volume detachments of low-angle mountain glaciers – more frequent than thought? The Cryosphere. ISSN 1994-0416. 15(4), s. 1751–1785. doi: 10.5194/tc-15-1751-2021.
• Kääb, Andreas; Strozzi, Tazio; Bolch, Tobias; Caduff, Rafael; Trefall, Håkon & Stoffel, Markus [Vis alle 7 forfattere av denne artikkelen] (2021). Inventory and changes of rock glacier creep speeds in Ile Alatau and Kungöy Ala-Too, northern Tien Shan, since the 1950s. The Cryosphere. ISSN 1994-0416. 15(2), s. 927–949. doi: 10.5194/tc-15-927-2021.
• Hugonnet, Romain; McNabb, Robert Whitfield; Berthier, Etienne; Menounos, Brian; Nuth, Christopher & Girod, Luc Maurice Ramuntcho [Vis alle 10 forfattere av denne artikkelen] (2021). Accelerated global glacier mass loss in the early twenty-first century. Nature. ISSN 0028-0836. 592, s. 726–731. doi: 10.1038/s41586-021-03436-z. Fulltekst i vitenarkiv Vis sammendrag

  Glaciers distinct from the Greenland and Antarctic ice sheets are shrinking rapidly, altering regional hydrology1, raising global sea level2 and elevating natural hazards3. Yet, owing to the scarcity of constrained mass loss observations, glacier evolution during the satellite era is known only partially, as a geographic and temporal patchwork4,5. Here we reveal the accelerated, albeit contrasting, patterns of glacier mass loss during the early twenty-first century. Using largely untapped satellite archives, we chart surface elevation changes at a high spatiotemporal resolution over all of Earth’s glaciers. We extensively validate our estimates against independent, high-precision measurements and present a globally complete and consistent estimate of glacier mass change. We show that during 2000–2019, glaciers lost a mass of 267 ± 16 gigatonnes per year, equivalent to 21 ± 3 per cent of the observed sea-level rise6. We identify a mass loss acceleration of 48 ± 16 gigatonnes per year per decade, explaining 6 to 19 per cent of the observed acceleration of sea-level rise. Particularly, thinning rates of glaciers outside ice sheet peripheries doubled over the past two decades. Glaciers currently lose more mass, and at similar or larger acceleration rates, than the Greenland or Antarctic ice sheets taken separately7,8,9. By uncovering the patterns of mass change in many regions, we find contrasting glacier fluctuations that agree with the decadal variability in precipitation and temperature. These include a North Atlantic anomaly of decelerated mass loss, a strongly accelerated loss from northwestern American glaciers, and the apparent end of the Karakoram anomaly of mass gain10. We anticipate our highly resolved estimates to advance the understanding of drivers that govern the distribution of glacier change, and to extend our capabilities of predicting these changes at all scales. Predictions robustly benchmarked against observations are critically needed to design adaptive policies for the local- and regional-scale management of water resources and cryospheric risks, as well as for the global-scale mitigation of sea-level rise.

• Jawak, Shridhar D.; Andersen, Bo Nyborg; Pohjola, Veijo A; Godøy, Øystein ; Hübner, Christiane & Jennings, Inger [Vis alle 32 forfattere av denne artikkelen] (2021). SIOS’s Earth Observation (EO), Remote Sensing (RS), and operational activities in response to COVID-19. Remote Sensing. ISSN 2072-4292. 13(4). doi: 10.3390/rs13040712. Fulltekst i vitenarkiv Vis sammendrag

  Svalbard Integrated Arctic Earth Observing System (SIOS) is an international partnership of research institutions studying the environment and climate in and around Svalbard. SIOS is developing an efficient observing system, where researchers share technology, experience, and data, work together to close knowledge gaps, and decrease the environmental footprint of science. SIOS maintains and facilitates various scientific activities such as the State of the Environmental Science in Svalbard (SESS) report, international access to research infrastructure in Svalbard, Earth observation and remote sensing services, training courses for the Arctic science community, and open access to data. This perspective paper highlights the activities of SIOS Knowledge Centre, the central hub of SIOS, and the SIOS Remote Sensing Working Group (RSWG) in response to the unprecedented situation imposed by the global pandemic coronavirus (SARS-CoV-2) disease 2019 (COVID-19). The pandemic has affected Svalbard research in several ways. When Norway declared a nationwide lockdown to decrease the rate of spread of the COVID-19 in the community, even more strict measures were taken to protect the Svalbard community from the potential spread of the disease. Due to the lockdown, travel restrictions, and quarantine regulations declared by many nations, most physical meetings, training courses, conferences, and workshops worldwide were cancelled by the first week of March 2020. The resumption of physical scientific meetings is still uncertain in the foreseeable future. Additionally, field campaigns to polar regions, including Svalbard, were and remain severely affected. In response to this changing situation, SIOS initiated several operational activities suitable to mitigate the new challenges resulting from the pandemic. This article provides an extensive overview of SIOS’s Earth observation (EO), remote sensing (RS) and other operational activities strengthened and developed in response to COVID-19 to support the Svalbard scientific community in times of cancelled/postponed field campaigns in Svalbard. These include (1) an initiative to patch up field data (in situ) with RS observations, (2) a logistics sharing notice board for effective coordinating field activities in the pandemic times, (3) a monthly webinar series and panel discussion on EO talks, (4) an online conference on EO and RS, (5) the SIOS’s special issue in the Remote Sensing (MDPI) journal, (6) the conversion of a terrestrial remote sensing training course into an online edition, and (7) the announcement of opportunity (AO) in airborne remote sensing for filling the data gaps using aerial imagery and hyperspectral data. As SIOS is a consortium of 24 research institutions from 9 nations, this paper also presents an extensive overview of the activities from a few research institutes in pandemic times and highlights our upcoming activities for the next year 2021. Finally, we provide a critical perspective on our overall response, possible broader impacts, relevance to other observing systems, and future directions. We hope that our practical services, experiences, and activities implemented in these difficult times will motivate other similar monitoring programs and observing systems when responding to future challenging situations. With a broad scientific audience in mind, we present our perspective paper on activities in Svalbard as a case study. Earth observation; Remote sensing; COVID-19; Svalbard; Earth System Science; SIOS

• Daiyrov, Mirlan; Narama, Chiyuki; Kääb, Andreas & Tadono, Takeo (2020). Formation and Outburst of the Toguz-Bulak Glacial Lake in the Northern Teskey Range, Tien Shan, Kyrgyzstan. Geosciences. ISSN 2076-3263. 10(11). doi: 10.3390/geosciences10110468. Fulltekst i vitenarkiv
• Altena, Bas & Kääb, Andreas (2020). Ensemble matching of repeat satellite images applied to measure fast-changing ice flow, verified with mountain climber trajectories on Khumbu icefall, Mount Everest. Journal of Glaciology. ISSN 0022-1430. 66(260), s. 905–915. doi: 10.1017/jog.2020.66. Fulltekst i vitenarkiv
• Haga, Odin Næss; McNabb, Robert Whitfield; Nuth, Christopher; Altena, Bas; Schellenberger, Thomas & Kääb, Andreas (2020). From high friction zone to frontal collapse: dynamics of an ongoing tidewater glacier surge, Negribreen, Svalbard. Journal of Glaciology. ISSN 0022-1430. 66(259), s. 742–754. doi: 10.1017/jog.2020.43. Fulltekst i vitenarkiv
• Strozzi, Tazio; Caduff, Rafael; Jones, Nina; Barboux, Chloe; Delaloye, Reynald & Bodin, Xavier [Vis alle 9 forfattere av denne artikkelen] (2020). Monitoring Rock Glacier Kinematics with Satellite Synthetic Aperture Radar. Remote Sensing. ISSN 2072-4292. 12(3). doi: 10.3390/rs12030559. Fulltekst i vitenarkiv
• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard. The Cryosphere. ISSN 1994-0416. 14( 11), s. 4217–4231. doi: 10.5194/tc-14-4217-2020. Fulltekst i vitenarkiv
• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard. The Cryosphere Discussions. ISSN 1994-0432. doi: 10.5194/tc-2020-124.
• Schuler, Thomas Vikhamar; Kohler, Jack; Elagina, Nelly; Hagen, Jon Ove Methlie; Hodson, Andrew & Jania, Jacek A. [Vis alle 13 forfattere av denne artikkelen] (2020). Reconciling Svalbard Glacier Mass Balance. Frontiers in Earth Science. ISSN 2296-6463. 8. doi: 10.3389/feart.2020.00156. Fulltekst i vitenarkiv
• Sterckx, Sindy; Brown, Ian; Kääb, Andreas; Krol, Maarten; Morrow, Rosemary & Veefkind, Pepijn [Vis alle 10 forfattere av denne artikkelen] (2020). Towards a European Cal/Val service for earth observation. International Journal of Remote Sensing. ISSN 0143-1161. 41(12), s. 4496–4511. doi: 10.1080/01431161.2020.1718240. Fulltekst i vitenarkiv
• Alexander, Andreas; Kruusmaa, Maarja; Tuhtan, Jeffrey; Hodson, Andrew; Schuler, Thomas & Kääb, Andreas (2020). Pressure and inertia sensing drifters for glacial hydrology flow path measurements. The Cryosphere. ISSN 1994-0416. 14(3), s. 1009–1023. doi: 10.5194/tc-14-1009-2020. Fulltekst i vitenarkiv Vis sammendrag

  Glacial hydrology plays an important role in the control of glacier dynamics, of sediment transport, and of fjord and proglacial ecosystems. Surface meltwater drains through glaciers via supraglacial, englacial and subglacial systems. Due to challenging field conditions, the processes driving surface processes in glacial hydrology remain sparsely studied. Recently, sensing drifters have shown promise in river, coastal and oceanographic studies. However, practical experience with drifters in glacial hydrology remains limited. Before drifters can be used as general tools in glacial studies, it is necessary to quantify the variability of their measurements. To address this, we conducted repeated field experiments in a 450 m long supraglacial channel with small cylindrical drifters equipped with pressure, magnetometer, acceleration and rotation rate sensors and compared the results. The experiments (n=55) in the supraglacial channel show that the pressure sensors consistently yielded the most accurate data, where values remained within ±0.11 % of the total pressure time-averaged mean (95 % confidence interval). Magnetometer readings also exhibited low variability across deployments, maintaining readings within ±2.45 % of the time-averaged mean of the magnetometer magnitudes. Linear acceleration measurements were found to have a substantially higher variability of ±34.4 % of the time-averaged mean magnitude, and the calculated speeds remained within ±24.5 % of the time-averaged mean along the flow path. Furthermore, our results indicate that prominent shapes in the sensor records are likely to be linked to variations in channel morphology and the associated flow field. Our results show that multimodal drifters can be a useful tool for field measurements inside supraglacial channels. Future deployments of drifters into englacial and subglacial channels promise new opportunities for determining hydraulic and morphologic conditions from repeated measurements of such inaccessible environments.

• Obu, Jaroslav; Westermann, Sebastian; Vieira, Gonçalo; Abramov, Andrey; Balks, Megan Ruby & Bartsch, Annett [Vis alle 9 forfattere av denne artikkelen] (2020). Pan-Antarctic map of near-surface permafrost temperatures at 1 km2 scale. The Cryosphere. ISSN 1994-0416. 14(2), s. 497–519. doi: 10.5194/tc-14-497-2020. Fulltekst i vitenarkiv Vis sammendrag

  Permafrost is present within almost all of the Antarctic's ice-free areas, but little is known about spatial variations in permafrost temperatures except for a few areas with established ground temperature measurements. We modelled a temperature at the top of the permafrost (TTOP) for all the ice-free areas of the Antarctic mainland and Antarctic islands at 1 km2 resolution during 2000–2017. The model was driven by remotely sensed land surface temperatures and downscaled ERA-Interim climate reanalysis data, and subgrid permafrost variability was simulated by variable snow cover. The results were validated against in situ-measured ground temperatures from 40 permafrost boreholes, and the resulting root-mean-square error was 1.9 ∘C. The lowest near-surface permafrost temperature of −36 ∘C was modelled at Mount Markham in the Queen Elizabeth Range in the Transantarctic Mountains. This is the lowest permafrost temperature on Earth, according to global-scale modelling results. The temperatures were most commonly modelled between −23 and −18 ∘C for mountainous areas rising above the Antarctic Ice Sheet and between −14 and −8 ∘C for coastal areas. The model performance was good where snow conditions were modelled realistically, but errors of up to 4 ∘C occurred at sites with strong wind-driven redistribution of snow.

• Treichler, Désirée Silvana; Kääb, Andreas Max; Salzmann, Nadine & Xu, Chong-Yu (2019). Recent glacier and lake changes in High Mountain Asia and their relation to precipitation changes. The Cryosphere. ISSN 1994-0416. 13(11), s. 2977–3005. doi: 10.5194/tc-13-2977-2019. Fulltekst i vitenarkiv
• Kääb, Andreas; Altena, Bas & Mascaro, Joseph (2019). River-ice and water velocities using the Planet optical cubesat constellation. Hydrology and Earth System Sciences (HESS). ISSN 1027-5606. 23(10), s. 4233–4247. doi: 10.5194/hess-23-4233-2019. Fulltekst i vitenarkiv
• McNabb, Robert Whitfield; Nuth, Christopher; Kääb, Andreas & Girod, Luc Maurice Ramuntcho (2019). Sensitivity of glacier volume change estimation to DEM void interpolation. The Cryosphere. ISSN 1994-0416. 13(3), s. 895–910. doi: 10.5194/tc-13-895-2019. Fulltekst i vitenarkiv
• Altena, Bas; Haga, Odin Næss; Nuth, Christopher & Kääb, Andreas (2019). Monitoring sub-weekly evolution of surface velocity and elevation for a high-latitude surging glacier using sentinel-2. International Archives of Photogrammetry, Remote Sensing and Spatial Information Sciences. ISSN 1682-1750. 42(2), s. 1723–1727. doi: 10.5194/isprs-archives-XLII-2-W13-1723-2019. Fulltekst i vitenarkiv
• Falaschi, Daniel; Kääb, Andreas; Paul, Frank; Tadono, Takeo; Antonio Rivera, Juan & Eduardo Lenzano, Luis (2019). Brief communication: Collapse of 4Mm3 of ice from a cirque glacier in the Central Andes of Argentina. The Cryosphere. ISSN 1994-0416. 13(3), s. 997–1004. doi: 10.5194/tc-13-997-2019. Fulltekst i vitenarkiv
• Obu, Jaroslav; Westermann, Sebastian; Bartsch, Annett; Berdnikov, Nikolai M.; Christiansen, Hanne H & Dashtseren, Avirmed [Vis alle 21 forfattere av denne artikkelen] (2019). Northern Hemisphere permafrost map based on TTOP modelling for 2000–2016 at 1 km2 scale. Earth-Science Reviews. ISSN 0012-8252. 193, s. 299–316. doi: 10.1016/j.earscirev.2019.04.023. Fulltekst i vitenarkiv
• Altena, Bas; Scambos, Ted A; Fahnestock, M & Kääb, Andreas (2019). Extracting recent short-term glacier velocity evolution over southern Alaska and the Yukon from a large collection of Landsat data. The Cryosphere. ISSN 1994-0416. 13(3), s. 795–814. doi: 10.5194/tc-13-795-2019. Fulltekst i vitenarkiv Vis sammendrag

  The measurement of glacier velocity fields using repeat satellite imagery has become a standard method of cryospheric research. However, the reliable discovery of important glacier velocity variations on a large scale is still problematic because time series span different time intervals and are partly populated with erroneous velocity estimates. In this study we build upon existing glacier velocity products from the GoLIVE dataset (https://nsidc.org/data/golive, last access: 26 February 2019) and compile a multi-temporal stack of velocity data over the Saint Elias Mountains and vicinity. Each layer has a time separation of 32 days, making it possible to observe details such as within-season velocity change over an area of roughly 150 000 km2. Our methodology is robust as it is based upon a fuzzy voting scheme applied in a discrete parameter space and thus is able to filter multiple outliers. The multi-temporal data stack is then smoothed to facilitate interpretation. This results in a spatiotemporal dataset in which one can identify short-term glacier dynamics on a regional scale. The goal is not to improve accuracy or precision but to enhance extraction of the timing and location of ice flow events such as glacier surges. Our implementation is fully automatic and the approach is independent of geographical area or satellite system used. We demonstrate this automatic method on a large glacier area in Alaska and Canada. Within the Saint Elias and Kluane mountain ranges, several surges and their propagation characteristics are identified and tracked through time, as well as more complicated dynamics in the Wrangell Mountains.

• Nuth, Christopher; Gilbert, Adrien; Köhler, Andreas; McNabb, Robert Whitfield; Schellenberger, Thomas & Sevestre, Heidi [Vis alle 9 forfattere av denne artikkelen] (2019). Dynamic vulnerability revealed in the collapse of an Arctic tidewater glacier. Scientific Reports. ISSN 2045-2322. 9. doi: 10.1038/s41598-019-41117-0. Fulltekst i vitenarkiv
• Treichler, Désirée Silvana; Kääb, Andreas; Salzmann, Nadine & Xu, Chong-Yu (2018). High Mountain Asia glacier elevation trends 2003–2008, lake volume changes 1990–2015, and their relation to precipitation changes. The Cryosphere Discussions. ISSN 1994-0432. doi: 10.5194/tc-2018-238.
• Gilbert, Adrien; Leinss, Silvan; Kargel, Jeffrey S.; Kääb, Andreas; Gascoin, Simon & Leonard, Gregory [Vis alle 9 forfattere av denne artikkelen] (2018). Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet. The Cryosphere. ISSN 1994-0416. 12(9), s. 2883–2900. doi: 10.5194/tc-12-2883-2018. Fulltekst i vitenarkiv
• McNabb, Robert Whitfield; Nuth, Christopher; Kääb, Andreas & Girod, Luc Maurice Ramuntcho (2018). Sensitivity of geodetic glacier mass balance estimation to DEM void interpolation. The Cryosphere Discussions. ISSN 1994-0432. doi: 10.5194/tc-2018-175.
• Kääb, Andreas; Leinss, Silvan; Gilbert, Adrien; Bühler, Yves; Gascoin, Simon & Evans, Stephen G. [Vis alle 19 forfattere av denne artikkelen] (2018). Massive collapse of two glaciers in western Tibet in 2016 after surge-like instability. Nature Geoscience. ISSN 1752-0894. 11(2), s. 114–120. doi: 10.1038/s41561-017-0039-7. Fulltekst i vitenarkiv
• Antonova, Sofia; Sudhaus, Henriette; Strozzi, Tazio; Zwieback, Simon; Kääb, Andreas & Heim, Birgit [Vis alle 9 forfattere av denne artikkelen] (2018). Thaw subsidence of a Yedoma landscape in Northern Siberia, measured in situ and estimated from TerraSAR-X interferometry. Remote Sensing. ISSN 2072-4292. 10(4). doi: 10.3390/rs10040494. Fulltekst i vitenarkiv
• Narama, Chiyuki; Daiyrov, Mirlan; Duishonakunov, Murataly; Tadono, Takeo; Sato, Hayato & Kääb, Andreas [Vis alle 8 forfattere av denne artikkelen] (2018). Large drainages from short-lived glacial lakes in the Teskey Range, Tien Shan Mountains, Central Asia. Natural Hazards and Earth System Sciences. ISSN 1561-8633. 18(4), s. 983–995. doi: 10.5194/nhess-18-983-2018. Fulltekst i vitenarkiv
• Girod, Luc Maurice Ramuntcho; Nielsen, Niels Ivar; Couderette, Frédérique; Nuth, Christopher & Kääb, Andreas (2018). Precise DEM extraction from Svalbard using 1936 high oblique imagery. Geoscientific Instrumentation, Methods and Data Systems. ISSN 2193-0856. 7, s. 277–288. doi: 10.5194/gi-7-277-2018. Fulltekst i vitenarkiv
• Barandun, Martina; Huss, Matthias; Usubaliev, Ryskul; Azisov, Erlan; Berthier, Etienne & Kääb, Andreas [Vis alle 8 forfattere av denne artikkelen] (2018). Multi-decadal mass balance series of three Kyrgyz glaciers inferred from modelling constrained with repeated snow line observations. The Cryosphere. ISSN 1994-0416. 12(6), s. 1899–1919. doi: 10.5194/tc-12-1899-2018. Fulltekst i vitenarkiv
• Daiyrov, Mirlan; Narama, Chiyuki; Yamanokuchi, Tsutomu; Tadono, Takeo; Kääb, Andreas & Ukita, Jinro (2018). Regional geomorphological conditions related to recent changes of glacial lakes in the issyk-kul basin, Northern Tien Shan. Geosciences. ISSN 2076-3263. 8(3). doi: 10.3390/geosciences8030099. Fulltekst i vitenarkiv
• Winsvold, Solveig Havstad; Kääb, Andreas; Nuth, Christopher; Andreassen, Liss Marie; Van Pelt, Ward J.J. & Schellenberger, Thomas (2018). Using SAR satellite data time series for regional glacier mapping. The Cryosphere. ISSN 1994-0416. 12(3), s. 867–890. doi: 10.5194/tc-12-867-2018. Fulltekst i vitenarkiv
• Paul, Frank; Bolch, Tobias; Briggs, Kate; Kääb, Andreas; McMillan, Malcolm & McNabb, Robert Whitfield [Vis alle 10 forfattere av denne artikkelen] (2017). Error sources and guidelines for quality assessment of glacier area, elevation change, and velocity products derived from satellite data in the Glaciers_cci project. Remote Sensing of Environment. ISSN 0034-4257. 203, s. 256–275. doi: 10.1016/j.rse.2017.08.038.
• Narama, Chiyuki; Daiyrov, Mirlan; Tadono, Takeo; Yamamoto, Minako; Kääb, Andreas & Morita, Reira [Vis alle 7 forfattere av denne artikkelen] (2017). Seasonal drainage of supraglacial lakes on debris-covered glaciers in the Tien Shan Mountains, Central Asia. Geomorphology. ISSN 0169-555X. 286, s. 133–142. doi: 10.1016/j.geomorph.2017.03.002. Fulltekst i vitenarkiv
• Strozzi, Tazio; Paul, Frank; Wiesmann, Andreas; Schellenberger, Thomas & Kääb, Andreas (2017). Circum-arctic changes in the flow of glaciers and ice caps from satellite SAR data between the 1990s and 2017. Remote Sensing. ISSN 2072-4292. 9(9). doi: 10.3390/rs9090947. Fulltekst i vitenarkiv
• Girod, Luc Maurice Ramuntcho; Nuth, Christopher; Kääb, Andreas; McNabb, Robert Whitfield & Galland, Olivier (2017). MMASTER: Improved ASTER DEMs for elevation change monitoring. Remote Sensing. ISSN 2072-4292. 9(7). doi: 10.3390/rs9070704. Fulltekst i vitenarkiv
• Paul, Frank; Strozzi, Tazio; Schellenberger, Thomas & Kääb, Andreas (2017). The 2015 surge of hispar glacier in the karakoram. Remote Sensing. ISSN 2072-4292. 9(9), s. 1–18. doi: 10.3390/rs9090888. Fulltekst i vitenarkiv
• Brun, Fanny; Berthier, Etienne; Wagnon, Patrick; Kääb, Andreas & Treichler, Désirée Silvana (2017). A spatially resolved estimate of High Mountain Asia glacier mass balances from 2000 to 2016. Nature Geoscience. ISSN 1752-0894. 10(9), s. 668–673. doi: 10.1038/ngeo2999. Fulltekst i vitenarkiv

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• Jawak, Shridhar D.; Pohjola, Veijo; Kääb, Andreas Max; Andersen, Bo Nyborg; Błaszczyk, Małgorzata & Salzano, Roberto [Vis alle 12 forfattere av denne artikkelen] (2023). Status of Earth Observation and Remote Sensing Applications in Svalbard. Remote Sensing. ISSN 2072-4292. 15(2). doi: 10.3390/rs15020513. Fulltekst i vitenarkiv
• Rouyet, Line; Lilleøren, Karianne Staalesen; Etzelmüller, Bernd; Kääb, Andreas Max; Christiansen, Hanne H. & Humlum, Ole [Vis alle 9 forfattere av denne artikkelen] (2022). SAR satellite remote sensing for mapping and monitoring Norwegian rock glaciers.
• Paul, Frank; Piermattei, Livia; Treichler, Désirée; Gilbert, Lin; Wuite, Jan & Strozzi, Tazio [Vis alle 7 forfattere av denne artikkelen] (2022). Three different glacier surges at a spot: What satellites observe and what not.
• Treichler, Désirée; Piermattei, Livia; Paul, Frank; Gilbert, Lin; Kääb, Andreas & Libert, Ludivine [Vis alle 9 forfattere av denne artikkelen] (2021). Observing small surging glaciers from space .
• Leclercq, Paul Willem; Kääb, Andreas; Altena, Bas & Bazilova, Varvara (2021). Detection of glacier surge activity using cloud computing of Sentinel-1 radar data.
• Andreassen, Liss Marie; Moholdt, Geir & Kääb, Andreas (2021). Satellitter overvåker norske breer. Det er det gode grunner til. [Avis]. Aftenposten.
• Truffer, M; Kääb, Andreas; Harrison, W.D.A.; Ospisova, G.; Nosenko, G. & Espizua, Lydia [Vis alle 11 forfattere av denne artikkelen] (2021). Chapter 13 - Glacier surges. I Haeberli, Wilfried (Red.), Snow and Ice-Related Hazards, Risks, and Disasters (Second Edition). Elsevier. ISSN 978-0-12-817129-5. s. 417–466. doi: 10.1016/B978-0-12-817129-5.00003-2.
• Hugonnet, Romain; McNabb, Robert Whitfield; Berthier, Etienne; Menounos, B.; Nuth, Christopher & Girod, Luc Maurice Ramuntcho [Vis alle 10 forfattere av denne artikkelen] (2020). A globally complete, spatially and temporally resolved estimate of glacier mass change: 2000 to 2019.
• McNabb, Robert Whitfield; Girod, Luc Maurice Ramuntcho; Nuth, Christopher & Kääb, Andreas (2020). An open-source toolset for automated processing of historic spy photos: sPyMicMac.
• Hugonnet, Romain; McNabb, Robert Whitfield; Berthier, Etienne; Menounos, B; Nuth, Christopher & Girod, Luc Maurice Ramuntcho [Vis alle 10 forfattere av denne artikkelen] (2020). Accelerated global glacier mass loss in the early twenty-first century.
• Alexander, Andreas; Obu, Jaroslav; Schuler, Thomas; Kääb, Andreas & Christiansen, Hanne H (2020). Subglacial permafrost dynamics and erosion inside subglacial channels driven by surface events in Svalbard.
• Kääb, Andreas (2019). The Ocean and Cryosphere in a Changing Climate.
• Kääb, Andreas (2019). The Ocean and Cryosphere in a Changing Climate .
• Kääb, Andreas (2019). The Ocean and Cryosphere in a Changing Climate.
• Kääb, Andreas (2019). The Ocean and Cryosphere in a Changing Climate.
• Kääb, Andreas (2019). A new era for observing glaciers from space.
• Kääb, Andreas (2019). Collapsing Glaciers.
• Kääb, Andreas & Treichler, Désirée Silvana (2019). High Mountain Asia glacier changes in the early 21st century.
• Altena, Bas; Wouters, Bert; Van den Broeke, Michiel; Kääb, Andreas; Raup, Bruce & Scambos, Ted A [Vis alle 7 forfattere av denne artikkelen] (2019). Eratosthenes.
• Altena, Bas & Kääb, Andreas (2019). Shifts in surface, speed, or shadows: What do we measure with different time-of-day overpasses of Sentinel-2.
• Altena, Bas & Kääb, Andreas (2019). Techniques to reveal inter-annual glacier flow from optical remote sensing.
• Alexander, Andreas; Kruusma, Maarja; Tuhtan, Jeffrey; Hodson, Andrew; Schuler, Thomas & Kääb, Andreas (2019). Sensing drifters as tool for glacial hydrology measurements.
• Alexander, Andreas; Kruusma, Maarja; Tuhtan, Jeffrey; Hodson, Andrew; Schuler, Thomas & Kääb, Andreas (2019). Sensing drifters as tool for glacial hydrology measurements.
• Altena, Bas & Kääb, Andreas (2019). River ice velocity from Sentinel-twogether and PROBA-VELOCITY. Vis sammendrag

  Most optical satellite systems are set in a sun-synchronous orbit. Because of such similar configurations, orbits-of-opportunity arise. These are combinations of satellites that sense near-simultaneously. Consequently, more information can be generated from a single satellite mission when it is orchestrated with another. Hence, one tactic is to let a small-satellite piggyback with a monitoring program. In this study we demonstrate such a strategy where we make use of the PROBA-V small-satellite in combination with Sentinel-2. The inclination of both satellites are very similar, as well as, their overpass time. This makes large scale extraction of displacements possible. One such application that can make use of this recording sequence is the monitoring of river ice break-up. In spring the melting season sets in and Arctic rivers increase in flow discharge. Eventually the water is able to break the ice cover, which will then float along. However, congestion of this ice results in jamming, associated flooding and ice run, causing damage to infrastructure and river banks. The long stretch of rivers make monitoring difficult, thus satellite remote sensing can be a means for identifying bottlenecks. The resolution of Proba-V is 100 meters, but the time separation results in drift of the floating ice in the order of 1 km. Hence, from data of this satellite pair we are able to generate a dense velocity field over the Lena River in Russia, which stretches more than 300 km. This study demonstrates the potential of the Sentinels as an umbrella for other smaller missions. This near-simultaneous configuration has not been envisioned as a mission objective, but is coincidence. However for a future small-satellite design through clever orbit configurations can easily enhance a satellites product portfolio.

• Altena, Bas; Schellenberger, Thomas & Kääb, Andreas (2019). Bringing together remote sensing data to produce region-wide glacier velocities. Vis sammendrag

  The recent increase of medium resolution satellite programs that consistently senses the Earth surface has brought great potential for glaciology. Satellites like the Sentinel-1&2 tandems, Landsat 7&8 duo and Rapideye constellation sense mountain ranges almost without missing a day. Consequently, high resolution time-series can be constructed, for snow-cover or crack propagation, or other single scene information. Properties derived from combinations of acquisitions, such as, glacier velocity is more challenging. Velocity estimation is based upon image matching, which can be hindered by coherence loss or cloud cover. Consequently, generated velocity data have gaps and have scattered coverage at different time intervals. This steady data stream has resulted in several initiatives to use image matching techniques in batch processing mode. Resulting in glacier velocity services being set-up (e.g.: cryoportal, GoLIVE, Geodetic data portal), but these initiatives are satellite specific. If such products are merged it is possible to increase temporal and spatial coverage and increase the reliability of the velocity estimates. We developed such a workflow that merges glacier velocity products of different time spans and type. This combined dataset covers several mountain ranges and has a regular time step at a monthly pace. This consistent time-series make it possible to observe glacier dynamics that are of short nature. As the satellite recordings already span several years, the dynamics of tidewater glaciers or (partial) surges can be observed and analyzed. This study therefor shows the great potential of bringing together different satellite systems.

• Altena, Bas; Armstrong, William & Kääb, Andreas (2019). On the origin of ogives.
• Altena, Bas; Scambos, Ted A; Fahnestock, M & Kääb, Andreas (2018). Automatic extraction of velocity time-series at mountain range scale from Landsat 8.
• Nuth, Christopher; Kohler, Jack; Köhler, Andreas; Lefeuvre, Pierre-Marie; Schuler, Thomas & Van Pelt, Ward [Vis alle 12 forfattere av denne artikkelen] (2018). The different dynamic personalities of two neighboring tidewater glaciers.
• Brun, Fanny; Berthier, Etienne; Wagnon, Patrick; Kääb, Andreas & Treichler, Désirée Silvana (2018). A spatially resolved estimate of High Mountain Asia glacier mass balances from 2000 to 2016: changes on debris-covered glaciers and comparison to ICESat and SPOT5-SRTM estimates.
• Treichler, Désirée Silvana; Kääb, Andreas & Brun, Fanny (2018). Recent glacier changes in High Mountain Asia. Response to climate and precipitation changes on the Tibetan Plateau.
• Gilbert, Adrien; Thøgersen, Kjetil; Kääb, Andreas; Nuth, Christopher; Schuler, Thomas & Gimbert, Florent (2018). Stable and unstable glacier flows: Role of friction law and feedback mechanisms at the basal interface .
• Girod, Luc Maurice Ramuntcho; Nielsen, Niels Ivar; Couderette, Frédérique; Hoslt, Marion Dominique; Lazizi, Laetitia Alice & Nuth, Christopher (2018). Extraction of glacier thickness change data and communication material from historical oblique imagery.
• Altena, Bas & Kääb, Andreas (2018). High-resolution surface and upper fjord circulation of Greenland fjords from optical remote sensing . Vis sammendrag

  Water within Greenland's fjords functions as conduit between the ice sheet and the Atlantic ocean. Exchange of energy and mass in the proglacial fjords is mainly driven by tides, wind, density fluctuations, glacial discharge and calving. All these forces change or alternate at different time scales and/or places. Measuring related (sub)surface fluxes in these fjords is complicated as fjord-ice hampers logistics and iceberg migration is able to damage measurement installations. However, an increasing fleet of optical satellites are sensing the Earth surface and can in this way observe Greenland fjords at multiple times a day. In this study we introduce a novel type of surface velocity extraction over even short time scales (minutes and hours apart), which exploits the multitude of satellites images taken daily over specific sites and is able to separate the surface velocities from the flows occurring lower in the water column. The resulting velocity fields are able to capture small scale features (±10m) over the full range of large fjords (±100km). Imagery from the Planet constellation, Sentinel-2 and Landsat 8 are used to extract the (sub)surface flow regime of Sermilik fjord. This can be estimated for several days within a week, making it possible to capture whole fjord variability and the mode of fjord circulation. Such detailed and complete circulation information will help to complement in-situ measurements and improve the modelling of ice-ocean interaction.

• Altena, Bas & Kääb, Andreas (2018). Doves & displacements.
• Altena, Bas & Kääb, Andreas (2018). Sensing a moving Arctic from space.
• Altena, Bas & Kääb, Andreas (2018). ICEFLOW: short-term movements in the cryosphere.
• Altena, Bas & Kääb, Andreas (2018). Kinematics in the Cryosphere from space.
• Haugnes, Gunhild M.; Tallaksen, Lena M.; Vogt, Rolf David; Storelvmo, Trude; Hessen, Dag Olav & Stordal, Frode [Vis alle 9 forfattere av denne artikkelen] (2018). Klimaforskerne tar temperaturen på tropesommeren. [Tidsskrift]. Titan.uio.no.
• Brun, Fanny; Berthier, Etienne; Wagnon, Patrick; Kääb, Andreas & Treichler, Désirée Silvana (2018). Author Correction: A spatially resolved estimate of High Mountain Asia glacier mass balances from 2000 to 2016. Nature Geoscience. ISSN 1752-0894. doi: 10.1038/s41561-018-0171-z.
• Altena, Bas & Kääb, Andreas (2018). Observing change in glacier flow from space. Frontiers for Young Minds. ISSN 2296-6846. 6, s. 1–9. doi: 10.3389/frym.2018.00009.
• Treichler, Désirée Silvana & Kääb, Andreas (2017). Measuring snow depth with a spaceborne laser.
• Treichler, Désirée Silvana; Kääb, Andreas; Brun, Fanny; Berthier, Etienne & Wagnon, Patrick (2017). DEM differencing for glacier mass balance in HMA.
• Lefeuvre, Pierre-Marie & Kääb, Andreas (2017). Surging glaciers in the Karakoram.
• Wolken, Gabriel J.; Liljedahl, Anne K.; Brubaker, Michael; Coe, J.A.; Fiske, G. & Christiansen, Hanne H [Vis alle 13 forfattere av denne artikkelen] (2021). Arctic Report Card 2021: Glacier and Permafrost Hazards. NOAA. Fulltekst i vitenarkiv
• Bergaas, Julie R.; Kääb, Andreas & Strout, James Michael (2021). Optical remote sensing and change detection for landslide mapping in a humid climate. Universitetet i Oslo.
• Altena, Bas; Kääb, Andreas; Leclercq, Paul Willem & Nuth, Christopher (2018). Optiske satellitter observerer endringer i isbevegelse. Universitetet i Oslo. ISSN 1501-7710. Vis sammendrag

  Komplekse sytemer er ofte målt med indikatorer. Isbreer endrer seg i takt med klimaet, og er derfor viktige klimaindikatorer. En bres massebalanse er relatert til klima og dens dynamikk er relatert til lokale egenskaper og systemets tilstand. Når vi vil ha en bedre oversikt over klimaet så må dynamikken på mange breer observeres. I denne doktorgradsavhandlingen brukes optiske satellitt systemer til å observere mange breer og registrere bredynamikk på kort og lang tidsskala. Fokuset i denne avhandlingen er å observere brebevegelse fra forskjellige optiske satellitt systemer for å registrere mest mulig pålitelig informasjon fra fire tiår med data fra satellittarkiver. Det introduseres en ny metode for å estimere brebevegelse fra forskjellige satellittbaner. Innfallsvinkelen er å estimere høydeforandringer og brebevegelse samtidig. I tillegg introduserer vi en bildesammenlikning basert på “triangle closure” som gjør metoden robust, men fortsatt pålitelig. Det er mulig å observere brebevegelse med korte tidsintervall med en ny metode basert på “optical flow”. Små perioder med økt brehastighet på grunn av økt vannmengde i det subglasiale systemet under en bre, kan bli observert nøyaktig både romlig og i tid. Dette er kun mulig på grunn av den økte tilgangen de siste årene på gratis og fritt tilgjengelige satellittbilder. Metoden gjør det mulig å raskt undersøke og identifisere om en bre er ustabil. For å bedre forstå bredynamikk kan man transformere data fra brebevegelse til strukturert informasjon. Jo mer brehastighetdata man har tilgjengelig, jo vanskeligere blir det å tolke hastighetssignalet til breen. Men ved å introdusere etterprosessering basert på votering så kan man filtrere ville observasjoner. Dette ble anvendt på et stort datasett av brehastigheter til å konstruere månedlige tidsserier over flere fjellkjeder i Alaska. Både årlige og sesongbaserte observasjoner var mulig å finne, også for mindre brearmer.

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