Information on glacier velocity is imperative to understand glacier mass, ice volume, topography, surge events of the glacier and response to climate change. Therefore, inter-annual surface ice velocity (SIV) of the Panchi Nala glacier has been calculated in the current study between the first two decades of the twenty-first century. To do so, the SIV has been computed by the feature tracking technique using the Co-registration of Optically Sensed Images and Correlation (COSI-Corr) method applied on the multi-temporal Landsat (TM and OLI) and sentinel -2 MSI images acquired between 2000 and 2021. The results of the study show that the mean velocity of the debris-covered tongue of the Panchi Nala Glacier is ∼10.60 ± 5.56 m/y during the study period. Additionally, the highest average glacier velocity is 13.77 ± 4.64 m/y, whereas the lowest is 8.92 ± 2.78 m/y, respectively, observed in 2005 and 2015. Also, the 95% confidence interval of the mean annual velocity lies between 9.76 and 11.43 m/y during the entire study period. The annual heterogeneity is linked with the variation of summer precipitation. Statistically, a 100 mm increment of summer precipitation can reduce the velocity around 1.3 m/y. The main reason behind this is the Panchi Nala glacier is located in high-elevation where the climate is much colder and during the summer precipitation, the lower temperatures cause the precipitation to take the form of snow, which freezes and accumulates on the glacier. This reduces the process of basal sliding. Further, detailed investigations with additional parameters need to be carried out to elucidate the comprehensive causes for inter-annual fluctuations in surface velocity. In this perspective, future research maybe directed towards higher temporal and spatial scale remote sensing-based investigations and validation of glacier surface velocity using field measurements, to better understand the glacier dynamics.

Keywords: Glacier surface ice velocity; debris cover; climate change; western Himalayas.

How to cite: Prajapati, M., Garg, P. K., Shukla, A., and Guha, S.: Dynamics of the Panchi Nala glacier, western Himalaya: trends and controlling factors., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10964, https://doi.org/10.5194/egusphere-egu23-10964, 2023.

Western Canada contains 72% of the glaciers within the Randolph Glacier Inventory (RGI) region 2 (Western Canada and USA), and these glaciers constitute 95% of the region’s total ice cover. Recent studies exploiting stereoscopic imagery from NASA’s Terra satellite (ASTER) have reduced biases in the number, type and distribution of glaciers used to assess regional glacier mass change. The elevation uncertainty of ASTER digital terrain models, in addition to infrequent sampling, confounds its use to detect trends in elevation change at seasonal scales or for small glaciers (< 1km²). Since summer 2014, the Hakai-UNBC Airborne Coastal Observatory (ACO) routinely acquires laser altimetric data at the end of the accumulation (late-April to early May) and ablation (early to late September) over many of western Canada’s glaciers and icefields using an aircraft equipped with an 1064-nm laser scanner and dedicated positional hardware. Post-processed uncertainties of repeated, co-registered elevational data over stable terrain yield uncertainties that are typically below ±0.3 m (±1s). Since 2020, our bi-annual acquisitions sample over 800 glaciers (about 2,000 km²), which constitutes about 15% of the total areal extent of ice in RGI-02. While the area-altitude distribution of ACO sampled glaciers largely accord with those of RGI-02, our sampling program captures fewer glaciers that exist at highest elevations, and the average glacier size surveyed by us is about three times larger than the average glacier size within RGI-02 (0.77 km²). Our archive reveals important aspects of glacier elevation change that cannot be obtained from existing publicly available sources of digital terrain data such as the magnitude of seasonal to inter-annual changes during the accumulation and ablation seasons, short-term horizontal transfers of mass, changes in volume and extent of transient late-lying snow, and the effects of short-term meteorological events (e.g. heat waves or forest fires) on regional melt events for a given year. We plan to release this archive to the public so it can be used to validate in-situ mass balance measurement programs, improve melt models and provide insight into physical factors that drive glacier change.

How to cite: Menounos, B., Heathfield, D., Beffort, S., Viner, N., Gonzalez Arriola, S., and White, R.: A nine-year, airborne laser scanning archive of glacier change, western Canada., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9820, https://doi.org/10.5194/egusphere-egu23-9820, 2023.

A developed boundary layer can decouple a glacier's response to the ambient meteorological conditions, though glacier retreat can limit this boundary layer development and increase a glacier’s sensitivity to climate change. We explore six years of distributed meteorological data on a small Swiss glacier in the period 2001-2022 to highlight its changing response to local conditions. We find an increased sensitivity (ratio) of on-glacier to off-glacier temperature changes as the glacier has retreated and its debris-cover area expanded. The glacier lost ~60% of area since 1994, coinciding with notable frontal retreat post 2005 and an observed switch from down-glacier to up-glacier winds in the upper ablation zone from 2001-2022. Increased sensitivity to external temperature changes is thus driven by a combination of increased up-glacier winds and the larger extent of ice exposed to warm air at a retreating, debris-covered glacier terminus. Calculated sensible heat fluxes on the glacier are therefore increasingly determined by the conditions occurring outside the boundary layer of the glacier, highlighting the expected negative feedback of smaller Alpine glaciers as the climate continues to warm and experience an increased frequency of extreme summers.

How to cite: Shaw, T., Buri, P., McCarthy, M., Miles, E., Ayala, Á., and Pellicciotti, F.: Meteorological Feedbacks on a Decaying Alpine Glacier, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12248, https://doi.org/10.5194/egusphere-egu23-12248, 2023.

Summer heat waves have a substantial impact on glacier melt as emphasized by the extreme summer of 2022 that caused unprecedented mass losses to the Swiss glaciers. Despite the dramatic impact on glaciers, the summer of 2022 offered a unique opportunity to analyze the implications that such extraordinary events have on glacier melt and related runoff release.

This study presents a novel approach based on computer-vision techniques for automatically determining daily mass balance variations at the local scale. The approach is based on the automated recognition of color-taped ablation stakes from camera images acquired at six sites on three Alpine glaciers in the period 2019-2022. The validation of the method revealed an uncertainty of the automated readings of ±0.81 cm d^-1. By comparing the automatically retrieved mass balances at the six sites with the average mass balance of the last decade derived from seasonal in situ observations, we detect extreme melt events in the summer seasons of 2019-2022.

The in-depth analysis of summer 2022 allows us to assess the impact that the summer heat waves have on glacier melt. With our approach we detect 23 days with extreme melt over the summer, emphasizing the strong correspondence between heat waves and extreme melt events. The Swiss-wide glacier mass loss during the 25 days of heat waves in 2022 is estimated as 1.27 ± 0.10 Gt, corresponding to 35% of the overall glacier mass loss in the summer of 2022. As compared to the 2010-2020 average glacier mass change, days with extreme melt in 2022 correspond to 56% of the mass change during the summer period, thus demonstrating the significance of heat waves for seasonal melt.

How to cite: Cremona, A., Huss, M., Landmann, J. M., Borner, J., and Farinotti, D.: Automated ice ablation readings reveal the significance of summer heat waves for glacier melt, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1062, https://doi.org/10.5194/egusphere-egu23-1062, 2023.

Iceland enjoys a much warmer climate than the average for its latitude. A major reason for this is the warm ocean currents in the Atlantic south of Iceland. There is a large heat flux from the ocean to the atmosphere and the air temperature therefore depends to a high degree on the ocean temperature. During the last roughly two decades, glaciers in Iceland have generally been retreating as well as having a negative mass balance due to a warmer climate, whereas during three decades prior to that, most of the glaciers in Iceland were advancing. The air temperature in Iceland south of the largest Icelandic glacier, Vatnajökull, showed a rise in temperature of about 1°C from 1995 to the early 2000’s and since then it has mostly remained at this high level. Often this warmer climate is attributed entirely to global warming. However, the temperature in the warm and saline Atlantic water south of Iceland also increased by about 1°C during the same period. This rise in ocean temperature was accompanied by an increase in salinity which indicates that the temperature rise was mostly due to a change in the ocean circulation, resulting in advection of warmer and saltier water to the area. In the period from 1995 to the early 2000’s the ocean heat flux with the Atlantic water across the Greenland-Scotland ridge increased by 21 TW, partly through Denmark Strait towards the continental shelf north of Iceland. The increased heat flux was attributed to a rising temperature as well as increased flow of Atlantic water. Only about 0.5% of this heat flux increase is needed to explain the recent melting of Icelandic glaciers. With a relatively sudden 1°C rise in temperature the glaciers will take decades to reach equilibrium with this new temperature and if the temperature does not decrease, the glaciers will continue to lose mass. There are records of advancing and retreating Icelandic glaciers from 1930 and they show a good correspondence with the Atlantic Multidecadal Oscillation (AMO), that reflects temperature variations in the North Atlantic Ocean.

How to cite: Jónsson, S.: The role of the ocean circulation in melting the glaciers in Iceland, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12667, https://doi.org/10.5194/egusphere-egu23-12667, 2023.

Glaciers distinct from the ice sheets melt quickly around the world. Rounce et al., 2023, recently projected (28±9) % glacier mass will be lost in 2100 compared to 2015 in the low-emission scenario SSP1-2.6. In our study, we focus on the observation of recent glacier mass change on Novaya Zemlya, Russian Arctic, using the SARIn altimeter CryoSat-2. Taking advantage of CryoSat-2's spatiotemporal resolution and a novel processor optimized for mountain glaciers, we show a prompt response to the surface temperatures modeled by the regional atmosphere model MAR. Prominent warm and high-melt years were 2013, 2016, and 2020, while 2014 featured lower surface temperature and melt than average. We discuss the potential drivers for those extreme years and furthermore exploit surface mass balance estimates to analyze the relative contribution of ice dynamics and surface processes to the observed mass loss acceleration, and regional variations therein.

How to cite: Haacker, J. and Wouters, B.: Prompt response of glaciers on Novaya Zemlya to recent warm summers shown by CryoSat swath data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11912, https://doi.org/10.5194/egusphere-egu23-11912, 2023.

With around 46 km², Nevado Coropuna (NC, 15°32’S, 72°39’W; 6377 m) is the largest tropical icecap in the world. NC is situated on a stratovolcano structure with six peaks over 6000 meters, in the arid border of the Andean plateau, Southern Peru. NC is a vital source of freshwater for the communities within the Majes valley and the vast irrigation plans located in the same valley and on the arid coastal strip. Our MOTICE project will model the evolution of NC until 2100 CE in response to climate change.

We present initial results on the modelling of NC, which will be used to tune the glaciological parameters for the projections under different RCP scenarios. Mass balance was modelled using the COupled Snowpack and Ice surface energy and MAss balance model in Python (COSIPY). This was forced with climate data for the 1950-2020 period from the ERA5-Land reanalysis, which provided surface pressure, cloud cover, incoming shortwave and longwave radiation, wind speed, 2-meter air temperature and relative humidity fields. This was combined with the RAIN4PE gridded product outputs for daily precipitation during the 1981-2015 period. The climate dataset was downscaled and validated with observed temperature and relative humidity from a weather station located on the Cavalca glacier (5800 m above sea level), at the northern part of NC. Glacier mass balance results were validated with measured mass balance in the same glacier for the 2014-2019 period. The mass-balance outputs from COSIPY were used for glacial flow modelling, using the Parallel Ice Sheet Model (PISM).

Subglacial topography was modelled using the Volume and Topography Automation (VOLTA) tool in a DEM that had been previously corrected with 70 differential GPR points measured “in situ”. The subglacial topography was also tuned and validated against in-situ GPR measurements in four glaciers of NC. Both GPR and GPS measurements were conducted during the 2022 fieldwork campaign, in which large areas of debris-covered ice were also located, mapped and measured. However, debris covered ice has not been considered in this initial model run.

Our preliminary results were compared to the actual 1955-2020 glacier surface evolution, which was retrieved from aerial photography and topographic maps for the initial stage in 1955 and from satellite images from 1975 onwards. This work highlighted the difficulty of modelling tropical glaciers, especially accounting for processes important to tropical ice, such as sublimation, and short-lived meteorological events.

How to cite: Pellitero, R., Bonshoms, M., Ely, J. C., and Liguori, G.: Modelling the future of Nevado Coropuna (Peru), the world’s largest tropical ice cap., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12767, https://doi.org/10.5194/egusphere-egu23-12767, 2023.

Similar to the Patagonian Icefields, the Cordillera Darwin Icefield in Tierra del Fuego experienced important ice loss during the last decades. The difficult accessibility and the harsh weather conditions in that area result in scarce in-situ observations of climatic conditions and glacier mass balances. Under these challenging conditions, this study investigates calibration strategies of surface mass balance models in the Monte Sarmiento Massif, western Cordillera Darwin, with the goal to achieve realistic simulations of the regional surface mass balance in the period 2000-2022.

We apply three calibration strategies ranging from a local single-glacier calibration to a regional calibration with and without the inclusion of a snowdrift parametrization. Furthermore, we apply four models of different complexity ranging from an empirical degree-day model to a fully-fledged surface energy balance model. This way, we examine the model transferability in space, the benefit of including regional mass change observations as calibration constraint and the advantage of increasing the model complexity regarding included processes. In-situ measurements comprise ablation stakes, ice thickness surveys and weather station records at Schiaparelli Glacier as well as elevation changes and flow velocity from satellite data for the entire study site. Performance of simulated surface mass balance is validated against geodetic mass changes and stake observations of surface melting.

Results show that transferring mass balance models in space is a challenge, and common practices can produce distinctly biased estimates. The use of remotely sensed regional observations can significantly improve model performance. Increasing the complexity level of the model does not result in a clear improvement in our case where all four models perform similarly. Including the process of snowdrift, however, significantly increases the agreement with geodetic mass balances. This highlights the important role of snowdrift for the surface mass balance in the Cordillera Darwin, where strong and consistent westerly winds prevail.

How to cite: Temme, F., Farías-Barahona, D., Seehaus, T., Jaña, R., Arigony-Neto, J., Gonzalez, I., Arndt, A., Sauter, T., Schneider, C., and Fürst, J. J.: Calibrating Surface Mass Balance Models at the Monte Sarmiento Massif, Tierra del Fuego, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2824, https://doi.org/10.5194/egusphere-egu23-2824, 2023.