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AGM28

#AGM28: Generic Meeting Session

Details

Full Title
#AGM28: Generic Meeting Session
Scheduled
TBA
Convener
Rainer Prinz
Co-Conveners
Emily Collier, Lindsey Nicholson,
Assigned to Synthesis Workshop
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Thematic Focus
No focus defined
Keywords
mountain film, inclusion and exclusion, gender and mountains

Description

This is a placeholer session for the #AGM28 meeting, what is held from Feb 27. 28, 2025 in Innsbruck. The focus of this meeting is on Alpine glaciology research, mainly from Europe. Informations and further details can be found on agm2025.info

Registered Abstracts

ID: 28.7305

Into the International Year of Glaciers’ Preservation 2025 – Perspectives from the World Glacier Monitoring Service

Michael Zemp
Gärtner-Roer, Isabelle; Nussbaumer, Samuel U.; Welty, Ethan; Dussaillant, Inés; Bannwart, Jacqueline; Paul, Frank; Hoelzle, Martin

Abstract/Description

Melting glaciers are icons of the climate crisis and severely impact local geohazards, regional freshwater availability, and global sea levels. The United Nations have designated 2025 as the International Year of Glaciers’ Preservation (IYGP; https://www.un-glaciers.org) to raise global awareness of glaciers’ importance and ensure that those relying on them or affected by their vanishing have access to the necessary data and information services. Starting in 2025, the 21st of March of each year will be recognised as the World Day of Glaciers. The World Glacier Monitoring Service (WGMS) – together with the United Nations Educational, Scientific and Cultural Organization (UNESCO) and the World Meteorological Organization (WMO) – helps to coordinate the implementation of the international glacier year and provides key facts and figures for related activities. Our presentation provides an update on regional to global glacier mass changes, including first estimates for 2023/24, as well as an update on the latest WGMS data and information products. We also highlight the importance of well-coordinated international glacier monitoring by the WGMS collaboration network, which combines field observations and remote sensing to track ongoing changes and related downstream impacts. In addition, we provide an overview of national events in preparation for the 21st of March, showcase ongoing projects to foster real-time monitoring, satellite intercomparison exercises, efforts toward a digital twin component for glaciers, and an outlook on the United Nations Decade of Action for Cryospheric Research 2025−2034.

ID: 28.7297

Snow cover variability and trends over Karakoram, Western Himalaya and Kunlun Mountains: Insights from MODIS (2001–2024) and Reanalysis Data

Cecilia Delia Almagioni
Manara, Veronica; Diolaiuti, Guglielmina Adele; Maugeri, Maurizio; Spezza, Alessia; Fugazza, Davide

Abstract/Description

Monitoring snow cover variability and its trends is critical for understanding its role in river formation and sustenance, as well as its response to climate change and its broader impact on the cryosphere. In this study, we utilized gap-filled MODIS snow cover data spanning the 2001–2024 period to investigate the spatial distribution and temporal evolution of three snow cover metrics: the length, start, and end of the snow cover season. Our analysis focused on fourteen regions encompassing the Karakoram, Western Himalayas, Kunlun Mountains, and part of the Tibetan Plateau. The results revealed a highly complex pattern of variability in the snow cover metrics, with elevation emerging as the primary factor influencing their spatial and temporal distribution. Nevertheless, a single explanatory factor for the observed variability remains elusive. The average length of the snow season varies considerably across the study area, ranging from approximately 14 days in arid desert regions to about 185 days in the Karakoram. Despite high interannual variability, no significant trend was detected for the snow cover metrics across the entire study area; however, region-specific trends were identified. This can be addressed to the Karakoram Anomaly problem, highlighted in literature. To gain deeper insights into the drivers of snow cover changes, we also examined meteorological variables and snow cover data derived from ERA5 and ERA5-Land reanalysis. Our findings indicate a good correlation between MODIS-derived snow metrics and reanalysis data over the 24-year period. Notably, the Taklamakan Desert and Kunlun Mountains exhibited a significant decrease in snow cover extent, likely driven by rising temperatures and declining precipitation found in these regions. Conversely, the Karakoram and Western Himalayas showed a positive trend in precipitation, which could at least partially explain the lack of trends in snow cover metrics and in snow cover extent. Unlike the global trend of declining snow cover, our findings reveal no significant decrease in snow cover extent over the Karakoram and Himalayas, underscoring the unique climatic and cryosphere dynamics of this region. Given the good correlation between MODIS-derived snow metrics and ERA5-Land reanalysis data, we further evaluated ERA5-Land snow cover trends across its entire time period starting in 1951, offering a longer-term perspective on snow cover variability.

ID: 28.7287

Initiating permafrost research in Bhutan: strategy and first results from the CRYO-SPIRIT project

Nadine Salzmann
Pellet, Cécile; Eden, Pema; Lhamo, Sonam; Gugerli, Rebecca; Naegeli, Kathrin; Karma, Karma; Gurung, DB

Abstract/Description

In the Himalayas, thawing permafrost is widely recognized as a major risk for initiating mass movements, influencing hydrological runoﬀ or impacting biodiversity. However, information and knowledge on the occurrence and changes of mountain permafrost in the Himalayas are still very scarce or absent in most areas, such as Bhutan. In the recently launched CRYO-SPIRIT project, Bhutan and Switzerland are joining hands to initiate permafrost research in Bhutan and to fill this important white spot. The project strategy focuses on three main aspects, namely (i) collecting and computing permafrost data using in-situ and remote sensing technologies, (ii) assessing and raising awareness about (future) risks related to permafrost thaw, including the development of adaptation strategies and (iii) building capacity of local researchers to sustain permafrost related monitoring, research and teaching activities in Bhutan. To assess permafrost, we focus on compiling the first regional map of potential permafrost distribution in Bhutan using in-situ Ground Surface Temperature (GST) measurements and remote sensing-based mapping of permafrost characteristic landforms, particularly rock glaciers. The first CRYO-SPIRIT field campaign took place in autumn 2024 in the vicinity of Thana glacier (Chamkhar Chhu Basin, Bumthang). This site was selected for its proximity to one of the three benchmark glaciers visited annually by researchers from Bhutan’s National Center for Hydrology and Meteorology (thus ensuring the long-term continuation of the measurements) as well as for the existence of an automatic weather station and the presence of identified periglacial landforms. During the field campaign, ground surface temperature loggers have been installed between 4300 m asl (below the lower limit of permafrost) and 5200 m asl along an elevation gradient and with diﬀerent exposition. In this contribution, we present the results of the first field campaign of the CRYO-SPIRIT project and intend to foster discussions and potential collaborations with international permafrost experts.

ID: 28.7284

What influences Algal blooms on the Greenland Ice Sheet? Insights from field work and satellite data at Qaanaaq glacier.

Davide Fugazza
Traversa, Giacomo; Di Mauro, Biagio; CalÃ¬ Quaglia, Filippo; Takeuchi, Nozomu; Suzuki, Takumi; Onuma, Yukihiko

Abstract/Description

The Greenland Ice Sheet is losing mass at unprecedented rates, leading to increased sea level rise. Melting of the ice sheet is accelerated by blooms of glacier ice algae, which lower ice albedo thus increasing absorption of solar radiation. In this study, we combine field work with collection of algae samples, spectroradiometer and satellite data from Sentinel-2 to create maps of algal abundance on Qaanaaq ice cap, Western Greenland based on a spectral index, and investigate the spatio-temporal patterns of algal blooms over the period 2016-2023. We calculate the spatially distributed timing and peak concentration of glacier ice algae, ice albedo and ice phenological metrics such as the start and end of ice ablation season as well as its length. We then correlate average and peak abundance of algal blooms with these phenological metrics, topographic and meteorological variables from downscaled reanalysis products. Glacier algae and albedo spatial distribution show high inter annual and spatial heterogeneity, highlighting the complex feedback mechanisms influencing their distribution across Qaanaaq glacier and the ice cap. Ice phenological metrics explain a relatively high part of the variance in peaks of algal concentration in individual years, e.g. in 2019 when 64% of the variance in peak algae concentration is explained by the length of the ablation season at Qaanaaq glacier. However, this relationship is highly dependent on the year. Meteorological data on air temperature and snowfall will be further used to better pinpoint the driving factors of algal blooms, as well as create models which can be potentially applied to the Greenland Ice sheet as a whole.

ID: 28.7280

First inventory of the paraglacial activity in the Venosta Valley (Italy) in relation to the recent glacial recession

Michele Di Biase
Crippa, Chiara; Callegari, Mattia; Fugazza, Davide

Abstract/Description

Glaciers are effective indicators of climate change and their constant loss in size and volume, is considered an undoubtable sign of global warming. In addition, glaciers provide different ecosystem services, but these benefits are threatened by climate change. Glacier shrinkage is worsening the geotechnical and mechanical properties of rocks in high mountain areas consequently affecting the slope stability and increasing risks for both alpinists and society at large. A high number of phenomena is consequence of the paraglacial dynamics whose intensity is directly linked to the rate of glacier melting and debuttressing. Within this context it is necessary to increase knowledge of the areas most subjected to slope instabilities to understand their predisposing conditions, the relationship with glacier melt and the effect they can exert on alpine paths and infrastructures. By means of orthophotos, Digital Elevation Models (DEM) and satellite data we investigated the glaciers of the Venosta Valley in South Tyrol. Firstly we focused on their evolution between 1997 and 2020. The outlines for the years 1997, 2005 and 2017 were retrieved from the official South Tyrol data portal, for the year 2020 we manually digitized all the glaciers on an updated orthophoto provided by the Bolzano Province and with InSAR data to detect debris covered portions of glaciers. Then we focused on the paraglacial events that discharged debris over glaciers. We manually digitized all the slope instability events, creating an inventory of the high altitude glacial related instabilities. These instabilities were distinguished between “rockfalls” and “side wall debris” according to their shape and position on the glaciers; these events were detected and analysed with orthophotos, DEMs and Google Earth 3D viewer of the last decades data. This study highlights that between 1997 and 2020 these glaciers suffered a strong area contraction (-38% in the Ortles-Cevedale group and -38.9% in the Ötztal group) and in these sectors it is possible to count a total of 500 instability events. With this research we investigated, for the study areas, the relationship between topography, glacier regression and slope instabilities providing insights to further investigate the connection between climate change and paraglacial dynamics in alpine regions. The slope instability inventory allowed us to compute statistics of rockfall main parameters in order to identify particularly vulnerable areas and evaluate the exposition of high alpine paths to climate related hazards.

ID: 28.7279

Decadal overview of mass balance at five Austrian glaciers and 2023/24 results

Lea Hartl
Seiser, Bernd; Stocker-Waldhuber, Martin; Bertolotti, Giulia; Gschwentner, Andreas; Lauria, Violeta; Conzelmann, Svenja; Helfricht, Kay; Fischer, Andrea

Abstract/Description

The glacier and permafrost group at the Institute for Interdisciplinary Mountain Research (Austrian Academy of Sciences) present an overview of the last ten years of mass balance data from the long term monitoring sites Jamtalferner (JTF), Mullwitzkees (MWK), Venedigerkees (VK), Stubacher Sonnblickkees (SSK), and Hallstätter Gletscher (HSG). Mass balance at these sites is measured with the direct glaciological method. The 2021/22 mass balance season was the most negative in the period of record at all sites with annual specific mass losses ranging from -2.2 m w.e. (VK) to -3.6 m w.e. (JTF). 2022/23 was also a major melt year, although losses were not as extreme as in 2022. Accumulation during the 2023/24 winter season was notably high at all sites with above average snow densities and specific winter mass balance. Nonetheless, the warm summer led to another very negative net season. Early snowfall in September 2024 limited late-season melt. Despite the summer snow, the ablation season extended substantially beyond the end of the hydrological year. Field work at all five glaciers has become more challenging in recent years. Ongoing, rapid glacier change makes access to some measurement locations increasingly difficult and the maintenance of the existing stake networks requires additional efforts. At JTF, measurements on the orographic left side of the glacier tongue had to be abandoned in 2024 due to the accelerating disintegration of this section. The time series of point mass balance at the affected ablation stakes have been discontinued.

ID: 28.7276

The second Glacier Mass Balance Intercomparison Exercise 2025–26

Michael Zemp
Gourmelen, Noel; Jakob, Livia; Nussbaumer, Samuel U.; Welty, Ethan; Piermattei, Livia; Berthier, Etienne

Abstract/Description

Melting glaciers are icons of the climate crisis and severely impact local geohazards, regional freshwater availability, and global sea levels. Well-constrained observations of glacier mass change and associated uncertainties are required to assess these downstream impacts and provide the baseline for calibrating and validating models for future projections. Previous assessments of global glacier mass changes were hampered by spatial and temporal limitations and the heterogeneity of datasets from different observation methods. The Glacier Mass Balance Intercomparison Exercise (GlaMBIE; https://glambie.org) set out to tackle these challenges through a community effort to collect, homogenise, combine, and analyse glacier mass changes from in situ and remote-sensing observations. This presentation summarises the results and lessons learned from the first GlaMBIE (2022−24) and introduces GlaMBIE-2, which runs from 2025 to 2026. In GlaMBIE-2, we aim to compile additional mass-change estimates to broaden observational coverage from different methods, extend the data series back to 1992 to align with available ice-sheet estimates, and update the time series to 2025 to cover the latest developments. In addition, we are running pilot studies to better understand the apparent bias between digital elevation model (DEM) differencing and altimetry and to increase the spatio-temporal resolution of our estimates to further hydrological applications. We invite the research community to participate in this collaborative effort by contributing their expertise and glacier mass change data, whether from in situ observations, repeat mapping from optical imaging and radar interferometry, laser and radar altimetry, and gravimetry.

ID: 28.7274

Deglaciation in western Austria: Perspectives from observations and modeling

Patrick Schmitt
Hartl, Lea; Schuster, Lilian; Helfricht, Kay; Abermann, Jakob; Maussion, Fabien

Abstract/Description

Most glaciers in Austria are expected to disappear in the coming decades, although the timing of ice loss varies across models and datasets. Regional glacier inventories show that approximately 19% of glacier area and 23% of glacier volume were lost between 2006 and 2017 in the Ötztal and Stubai mountain range (Tyrol, Austria). Five very small glaciers disappeared between 2006 and 2017 and are no longer included in the most recent inventory for the region. Using a novel calibration method based on high-resolution regional inventory data, projections by the Open Global Glacier Model (OGGM) indicate that 2.7% of the 2017 glacier volume in the region will remain by 2100 in a global warming scenario of +1.5°C above pre-industrial temperatures. In a +2°C scenario, this volume is reached around 30 years earlier and deglaciation is practically complete by 2100 (0.4% of 2017 volume remaining). Current warming trajectories (+2.7°C) suggest near-total ice loss before 2075. Over 100 glaciers, roughly one third of the glaciers in the study region, are likely to disappear by 2030 even in the optimistic +1.5°C scenario. We will present key results from our assessment of glacier evolution in the Ötztal and Stubai mountains until 2100 (preprint: https://doi.org/10.5194/egusphere-2024-3146). Additionally, we would like to share what we learned from combining the monitoring and modeling approaches of the two first-authors. We intend to touch on questions such as: – What sort of observations would be most helpful for improved glacier evolution modeling at regional scales? – How could the observations community better support modeling efforts in terms of data acquisition, curation, and format? – What are limitations and challenges related to observational data that modelers should be aware of? – Which observed melt-accelerating processes are not resolved in mass balance modeling and how might this be improved?

ID: 28.7273

Goodbye Glaciers!? – A hiking signpost project to raise glacier loss awareness

Patrick Schmitt
Schuster, Lilian; Fischer, Alexander; Juen, Irmgard; Gurgiser, Wolfgang

Abstract/Description

Inspired by the International Year of Glaciers’ Preservation 2025, the “Goodbye Glaciers?!” project plans to place signposts across Europe or even beyond — from cities to mountains — pointing to glaciers and showing the year they might be mostly gone if current climate policies continue. Each signpost has a QR code that links to an individual website for each glacier. 3D animations give an impression, how the glaciers might look like in the future under 1.5°C and 2.7°C global warming. While many glaciers in Central Europe may be lost, reducing emissions could still save a large amount of glacier ice worldwide which is a key message we want to spread. The website can be reached at https://goodbye-glaciers.info/ and the first signpost is presented to the public at the AGM. We will share more details and behind-the-scenes information through our poster.

ID: 28.7270

HLSL30 vs. Landsat 8: A Cross-Comparison of Albedo Products in the Karakoram Range

Blanka Barbagallo
Fugazza, Davide; Diolaiuti, Guglielmina Adele

Abstract/Description

Surface albedo is a critical parameter influencing glacier energy balance and melt processes, particularly in debris-covered and clean-ice glaciers. In this study, we focus on glaciers in the Karakoram Range, assessing the performance of the Harmonized Landsat Sentinel-2 (HLSL30) albedo product against Landsat 8 for the period 2017–2019. We chose this period because of the different snow coverage on the study area. Following methodologies adapted from previous cross-comparison studies, we analyze spatial and temporal variability in surface albedo across debris-covered (e.g., Dook Pal, Hinarche, Biafo) and clean-ice glaciers (e.g., Barpu, Passu). We selected glaciers of different sizes also to better test the spatial variability of the HLSL30 product. The study employs Google Earth Engine to generate and correct the albedo images of the two products, later analyzed thought R and GIS software. Preliminary results indicate a general agreement between the two datasets, with exceptions influenced by seasonal and glacier-specific conditions, with differences in debris-covered versus clean-ice surfaces. These insights highlight the importance of high-quality albedo products for monitoring glacier responses to climate change in regions with complex terrain and significant glaciological heterogeneity. This study underscores the critical role of satellite-derived albedo data for advancing our understanding of the energy balance in glacierized regions. Future work will further refine the analysis, incorporating broader datasets. These efforts aim to enhance the applicability of harmonized albedo products for long-term glacier monitoring in remote high-mountain environments where in situ measurements are not always available.

ID: 28.7267

Multi-sensor satellite observations of snow area extent in mountain regions

Maria Heinrich
Nagler, Thomas; Schwaizer, Gabriele; Moelg, Nico

Abstract/Description

Detailed information on the extent of the seasonal snow in high mountain regions is needed for applications in snow hydrology, management of water resources and glaciology. Due to the high spatial variability of seasonal snow in space and time, high resolution satellites provide efficient means for comprehensive snow monitoring in high mountain terrain. We report on the development of an advanced method for monitoring snow extent from multiple optical satellite data optimized for scientific and operational application in mountain areas. Regarding snow extent, we developed a multispectral unmixing approach that accounts for variations in illumination across mountainous terrain and offers flexibility regarding the optimum use of spectral sensor capabilities. Especially in mountain areas topographically induced shadow zones are common and cause problems in detection of snow using standard algorithms. Our approach separates regions illuminated by the sun from shaded regions using spectral classification rules and solar illumination conditions together with a DEM for detecting different snow free and fully snow covered Endmembers by applying adapted spectral band combinations. The algorithm is designed to provide consistent snow extent estimates from satellite sensors with different spatial resolution and spectral channels, such as sensors of the Copernicus Sentinel-2 and Sentinel-3 missions. By combining both satellite missions, we provide daily medium resolution snow products (300m) from Sentinel-3 SLSTR / OLCI together with high resolution snow products with 20 m pixel size from Sentinel-2, acquired every few days over the Alps and other mountain regions. Maps of uncertainty are attached to the snow extent products. In the presentation we outline the snow mapping procedure, show examples of snow products for different mountain regions worldwide, and report on the quality of the products in comparison with snow information from other sources.

ID: 28.7345

Turbulent Fluxes in a Land Terminatng Vertical Ice Cliff

Marie Schroeder
Prinz, Rainer; Nicholson, Lindsey; Abermann, Jakob; Steiner, Jakob; Stiperski, Ivana; Winkler, Michael

Abstract/Description

Land-terminating ice cliffs are rare features of the cryosphere, displaying unique atmosphere-cryosphere interactions due to their vertical nature. Although the ice cliff surface is small compared to the total glacier surface, the mass balance of the vertical face can play a decisive role in glacier ablation, due to the cliff’s altered exposure to radiative fluxes and modulation of turbulent heat fluxes. Understanding the boundary layer fluxes over these vertical ice walls is therefore essential for accurately modeling the melt of the cliff and other related processes. Our primary research focuses on ice cliffs in northern Greenland, where we aim to investigate how boundary layer dynamics shape their microclimate and ablation processes. To complement this work, we analyze a unique high frequency dataset collected from an ice cliff on Kilimanjaro during a 40-hour campaign in 2010. Two 3D sonic anemometers were deployed to monitor turbulence —one on the ground in front of the cliff and another on the cliff face. This dataset provides an opportunity to examine the turbulence structure specific to vertical ice cliffs and explore whether heat and moisture fluxes calculated from low- and high-frequency measurements are consistent. This allows us to determine whether low-frequency data is sufficient to calculate turbulent fluxes at sites without high-frequency instrumentation, as in Greenland. The vertical nature of ice cliffs presents distinct challenges for turbulence measurements, including determining the mean flow direction, identifying dominant turbulent flux directions, and optimizing coordinate rotation methodologies. By addressing these challenges, the Kilimanjaro dataset not only enhances our understanding of turbulent fluxes but also informs their representation in melt models, contributing to more accurate predictions of ice cliff ablation.

ID: 28.7351

Water pockets in Alpine glaciers: what are they, why do they form, and how do they burst?

Christophe Ogier
FISCHER, Mauro; WERDER, Mauro A.; HUSS, Matthias; HUPFER, Mauro; JACQUEMART, Mylène; GAGLIARDINI, Olivier; GILBERT, Adrien; HÖSLI, Leo; THIBERT, Emmanuel; VINCENT, Christian; FARINOTTI, Daniel

Abstract/Description

The term “water pocket” is often used as an umbrella term to describe the unknown origin of glacial outburst floods. There is currently no consensus on its definition and the formation and rupture mechanisms of water pockets remain poorly understood. Here, we define a glacial water pocket as an englacial or subglacial water-filled cavity with a volume larger than 1000 m3. Glacier outburst floods originating from the rupture of a water pocket are called water pocket outburst floods (WPOFs). WPOFs are in contrast to glacier lake outburst floods (GLOFs), for which the water giving rise to a flood stems from a detectable reservoir located either in the glacier forefield, at the surface of the glacier, at the glacier margin, or at the glacier base.

Here, we summarize the mechanisms behind WPOFs from alpine glaciers by analyzing their spatial and temporal distribution, pre-event meteorological conditions, and the glacio-geomorphic features of the glaciers from which the floods originate. We updated an inventory of known WPOFs in the Swiss Alps to 91 events from 37 individual glaciers. Among all the recorded events, 64 events have direct observations of the flood at the glacier tongue, while 27 events are characterized as speculative because of the lack of direct observations. Infrastructure damage was reported for 43 events, and two WPOFs caused the death of three people. Most WPOFs occurred between June and September, linked to meltwater input. Meteorological data indicate anomalously high temperatures during the days preceding most events and heavy precipitation on 25 % of days for which WPOFs occur, indicating that water pockets typically rupture during periods of high water input.

Based on the collected information, we propose four mechanisms of water pocket formation: temporary subglacial channel blockage, hydraulic barriers, water-filled crevasses, and accumulation of liquid water behind barriers of cold ice (thermal barriers). Overall, our analysis highlights the challenge of understanding WPOFs due to the sub-surface nature of water pockets, emphasizing the need for field-based research to improve their detection and monitoring.

ID: 28.7398

The influence of westerly moisture transport events on Kilimanjaro’s glaciers

Robert Peal
Collier, Emily

Abstract/Description

Rapidly retreating glaciers in Eastern Africa, such as at the summit of Kilimanjaro, are highly sensitive to moisture and precipitation variability. On sub-seasonal timescales, previous research has shown that precipitation variability in this region is closely related to the wind direction, with precipitation more probable on days where the wind blows anomalously from the west, advecting moisture from the Congo basin. However, the exact nature of the westerly circulation and the conditions under which it forms are not fully understood. Here, we present a multi-decadal analysis of East African westerly winds. We use methods developed from studies of atmospheric rivers to objectively identify “westerly moisture transport events” (WMTEs), facilitating new insights into the seasonal distribution and importance of these westerlies, the regions within Eastern Africa where they occur, and the role of both the Madden-Julian Oscillation and tropical cyclones in their development. Finally, we also investigate the role of WMTEs as drivers of sub-seasonal precipitation variability for the whole region and at high elevations near the glaciers on Kilimanjaro.

ID: 28.7417

Potentials and challenges of free SPOT 5 stereo imagery archive to derive glacier elevation changes in the Alpine region

Francesco Ioli
Mattea, Enrico; Piermattei, Livia

Abstract/Description

Satellite stereo photogrammetry is commonly used for quantifying glacier elevation changes and computing geodetic glacier mass balances, particularly at regional to global scales. Several satellite sensors enable stereo or tri-stereo imaging for DEM generation, including the Terra ASTER, SPOT 5 HRS, SPOT 6-7 NAOMI, Pléiades HiRI, and Pléiades Neo Imager. Each has advantages and limitations in terms of spatial resolution, temporal coverage, and data availability. Since 2000, ASTER has provided a 20-year global stereo archive. However, the coarse DEM resolution of ~30 m is not optimal for capturing changes in small alpine glaciers. SPOT 6-7 and Pléiades offer finer resolutions (1.5 m–0.3 m), but their usage is limited by shorter time series, higher costs, and limited stereo archives. The Pléiades Glacier Observatory provides publicly accessible 2 m DEMs for 140 glacierized areas with ~5-year revisit intervals, but its time series starts only in 2016.
This study aims to assess the capabilities and challenges of the SPOT 5 HRS archive for glacier elevation changes in the Alps. Operating from 2002 to 2015, SPOT 5 HRS offers global coverage with a resolution about 4.5 times finer than ASTER and a swath width of 120 km, enabling ~10 m resolution DEMs. Since 2021, CNES has made SPOT 5 imagery freely available through the SPOT World Heritage program. Although SPOT 5’s temporal coverage complements newer commercial stereo satellites and provides high-resolution elevation changes for the early 21st century, it remains underutilized for glaciological analysis. Challenges include its 8-bit radiometric resolution, the lack of Rational Polynomial Coefficients (RPC) camera models, which must be computed from the exact camera models, and rectangular pixels caused by the 10 m image resolution at nadir with 5 m along-track oversampling.
We analyzed the spatial and temporal coverage of the SPOT 5 HRS archive for Alpine glaciers, focusing on the availability of stereo pairs and seasonal acquisition patterns. Case studies on the Aletsch and Belvedere Glaciers benchmark SPOT 5 stereo reconstruction and DEM accuracy against ASTER. Glacier elevation changes over multiple decades are estimated using SPOT 5, SPOT 6-7, and Pléiades datasets and validated against ASTER-derived estimates.
Despite SPOT 5’s challenges, the archive offers a valuable resource for the glaciological community, as it fills a critical gap for long-term analyses of glacier elevation changes.

ID: 28.7433

Variations in subglacial sediment transport capacity with respect to water discharge

Ian Arburua Delaney
Tedstone, Andrew; Werder, Mauro W.; Farinotti, Daniel

Abstract/Description

The sediment transport capacity in subaerial and subglacial channels depends on shear stress at the channel bed, influenced by water velocity and geometry. Subaerial channels accommodate discharge variations through flow depth, width, and velocity changes. In contrast, subglacial channels, confined by overlying ice, grow slowly due to frictional heating, so sudden discharge changes primarily affect velocity. This study presents formulations for sediment transport capacity in both channel types and applies models to hydrographs from an Alpine glacier and the Greenland Ice Sheet. Results show that sediment transport capacity often peaks before maximum discharge, causing hysteresis that decouples sediment transport and water flow in subglacial systems. Subglacial channels can sustain high sediment transport across various discharge levels. Reducing discharge variability diminishes hysteresis, sometimes producing sediment-water discharge relationships resembling subaerial systems. Additional experiments highlight the non-linear behavior of subglacial sediment transport, resulting in greater variability. However, subglacial transport capacity variations approach subaerial ones when subglacial discharge changes in equilibrium with channel size. This work offers a framework for comparing sediment transport capacity in glacial and subglacial systems. The results improve interpretations of sediment discharge records in glacierized catchments influenced by different hydro-climatic conditions and contribute to predicting sediment fluxes under changing climatic and hydrological regimes.

ID: 28.7449

Foehn winds on McCall Glacier, Alaska: Identification and impacts

Leo Schlagbauer

Abstract/Description

Exceptionally strong, gusty and warm winds were observed at the McCall glacier in the Brooks Range in North Alaska by local scientist Matt Nolan. He reported that these winds often caused substantial amounts of snow scour during winter. These winds were identified as Foehn with a statistical mixture model using automatic weather station data of McCall glacier as well as reanalysis data of the ERA5 dataset. For one main target station in the ablation area of McCall glacier, a Foehn frequency of 5% was found in the period 2008 – 2014. For further investigation one winter and one summer case study was conducted for the same location, both presenting an event where Foehn had a significant impact on the glacier. During the winter case study strong winds up to 15 m s−1 caused erosion of a snow cover with a depth of 0.3 m. In general strong winds, most of them being Foehn, are estimated to erode a snow mass of 100 mm SWE per winter. This equals 50 % of the annually received snowfall which can thus not contribute to winter accumulation. In the summer case study Foehn led to air temperatures above 10 °C and wind speeds of approximately 10 m s−1. This caused an enhanced sensible heat flux with peaks up to 250 W m−2, ultimately leading to significant surface melt. Overall, however, the influence of Foehn during summer is estimated to be small as such strong events were found to be rare.

ID: 28.7453

Changing ablation patterns on glacier in the Alps during the melting seasons 2015 – 2023 observed by means of Sentinel-2 data

Gabriele Schwaizer

Abstract/Description

Glaciers in the European Alps are reflecting the effects of shorter winter periods with reduced precipitation and prolonged summer seasons and rising temperatures. These changes appear to be occurring with greater frequency and intensity in recent years. High-resolution optical satellite data from the Sentinel-2 mission, available since 2015, provide surface observations not only of individual glaciers but also of entire mountain ranges at the same time. The improved temporal resolution of these observations—10-day intervals since 2015, and 5-day intervals since 2017—has significantly increased the availability of cloud-free observations compared to earlier periods, when high-resolution optical satellite data were available only every 16 days. Based on optical satellite imagery, glacier surfaces can be classified into snow, clean ice, and snow-free debris cover. Firn areas, however, can have similar spectral reflectance characteristics as old, dirty snow from the previous winter or bright ice, making it difficult to distinguish between these surface types. To address this, a classification of firn areas using Sentinel-2 data was tested for manually selected dates. In optical satellite data, clouds obscure the Earth’s surface and are thus masked over glaciated regions.
The Sentinel-2 dataset enables the study of changes in glacier surface conditions on multiple dates during the melting season across consecutive years. An analysis of Sentinel-2 time series for glaciers in the Alps from 2015 to 2023 reveals a change in the snow areas on glaciers during the ablation season in recent years. The main ablation period, marked by a significant decrease in snow-covered areas, starts in late May/early June, and ends with a maximum ablation extent in late August/early September across all observed years. However, following the first snow fall event after this main ablation period, occurring typically in early September, a second significant ablation phase has been observed in recent years, which can extend into late October. Although the maximum extent of the ablation area is reached at the end of the main ablation period in all analysed years, significant reduction in snow cover also occurs during the second melt period, exposing large areas of glacier ice. This prolonged melting of snow and ice areas contributes to the reduction of glacier mass.
In this presentation, examples of the glacier surface classifications will be shown, and the temporal and spatial variabilities of the glacier surface classes observed from Sentinel-2 data during the melting periods 2015 to 2023 on selected individual glaciers and for glaciers in selected mountain ranges will be discussed.

FS 3.205: Mountain Festivals: The Representation, Marketing, and Consumption of Mountaineering Cultures

FS 2.102: Adaptation strategies and pathways for resilience in mountain regions

#IMC: September 14 - 18 2025

AGM28

#AGM28: Generic Meeting Session

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