Ice Bodies Research Articles

Pyrenean glaciers are disappearing fast: state of the glaciers after the extreme mass losses in 2022 and 2023

Given rapid glacier thinning and retreat observed in the Pyrenees in recent decades, an updated glacier inventory and continuous mass balance assessments are important to understand the ongoing variability and changes of these very small glaciers (< 0.5 km2). The mass balance years 2021/22 and 2022/23 were characterised by prolonged extreme heat waves and reduced snow duration that severely affected the Pyrenees, which also impacted their glaciers. This paper reviews the criteria for classifying ice bodies as glaciers or ice patches, presents the latest high-resolution glacier inventory for the Pyrenees, and quantifies the mass losses caused by the extreme climate conditions in 2022 and 2023. The glacierised area was determined by manual mapping of high-resolution (0.2 m spatial resolution) aerial orthomosaics acquired by unmanned aerial vehicles (UAVs) and aerial orthophotos (0.25 m spatial resolution) for the few glaciers not surveyed by UAVs. 3D point clouds, also obtained from UAV flights, were used to update the results for the change in surface elevation (glacier thickness) and mass balance between 2020 and 2023. For the Pyrenees, the total glacierised area in 2023 is 143.2 ± 1.8 ha in 15 different glaciers and 8 ice masses were degraded to ice patches according to our criteria. The resulting area change between 2020 and 2023 is -94.8 ha, representing a -39.8% decrease of the glaciarised area from 2020 to 2023, increasing the annual ratio of area change from 2020 to 2023 by -8.7% yr−1 compared to the period 2011–2020 (-2.4% yr−1). The change in glacier thickness measured on 12 glaciers shows a decrease of -2.52 m yr−1 for the period 2020–2023, which represents a significant acceleration in glacier thickness loss compared to -0.80 m yr−1 for the period 2011–2020. The three glaciers (Infiernos, Monte Perdido and Aneto) on which annual geodetic measurements were carried out showed slightly higher glacier thickness losses (-0.91 m yr−1) in the first mass balance year (2020/21) than in the previous decade (2011–2020), while the losses in the last two mass balance years (2021/22 and 2022/23) were three to four times higher (-3.42 m yr−1 and -3.07 m yr−1 respectively) and exceeded the record values.

Numerical Simulation Study on Ice–Water–Ship Interaction Based on FEM-SPH Adaptive Coupling Algorithm

To address the impact of layered ice and seawater on polar vessels navigating in icy waters, this study employs a coupled finite element method (FEM) and smoothed particle hydrodynamics (SPH) algorithm to simulate the collision dynamics between the bow and stern of a designated icebreaker and the ice layers. The foundational principles and deployment strategies of the coupling algorithm have been meticulously delineated, with a subsequent simulation conducted to model the trajectory of icebreakers navigating through stratified ice conditions. The ice load on the hull, the movement of broken ice bodies, and the temporal variation of ice resistance during collision were analyzed. The method’s applicability and precision were substantiated through a comparative analysis between the simulated ice resistance outcomes and the ice load estimations derived from the Lindqvist formula. Finally, the differences between the bow and stern icebreaking methods were compared. The research findings indicate that the coupling algorithm demonstrates high precision in simulating the navigation of icebreakers under layered ice conditions, aligning with actual scenarios. This provides a solid foundation for further exploration of the ice load on polar vessels. Furthermore, at equivalent speeds and ice thicknesses, stern icebreaking was observed to induce greater oscillations in ice load and yield a higher mean resistance compared to bow icebreaking.

Mechanical Analysis of the Critical Conditions for Trapping and Detachment of Microscale Air Bubbles on the Pure Water Freezing Front.

Icing is a widespread phase change phenomenon with implications for daily life and industrial production. Air bubbles form on the freezing front of pure water with dissolved air during the icing, which may affect the physical properties of ice. Controlling the behavior of air bubbles will be one method to change the physical properties of ice. To analyze the critical conditions for trapping and detachment of microscale air bubbles on a pure water freezing front, a mathematical model describing the forces on air bubble is developed on the basis of the principle of force equilibrium. Results show that the average accuracy of the present model in predicting the average air bubble detachment radius is about 62%, which is 30% higher than the model with the best prediction accuracy in the literature. Buoyant, temperature gradients, and hydrodynamic forces push air bubbles to detach from the freezing fronts, while adhesion force and gravity impede their detachment. Temperature gradient and adhesion forces are the main factors affecting the detachment of air bubbles from freezing fronts. The temperature gradient has the greatest effect on the air bubble detachment radius, while the tilt angle and liquid density have a lesser effect. When the temperature gradient is increased from 1000 to 10 000 K/m, the air bubble detachment radius decreases by 37.78%. Studying the forces acting on the air bubbles on the pure water freezing front is an important reference for the production of special ice bodies, phase change cold storage, and de-icing technology.

Distribution of mercury and methylmercury in ice-water-sediments in lakes during the freezing period under the influence of ice cover

The presence of lake ice cover alters the subglacial water environment, thereby influencing the migration and transformation of mercury (Hg) and methylmercury (MeHg) within the ice-water-sediment media of lakes. This study investigated the occurrence characteristics of mercury and methylmercury in various environmental compartments within lakes located at high latitudes in cold regions during the freezing period. To this end, Wuliangsuhai Lake, the largest freshwater lake situated at 40°N in China, was selected as the study site. The contents of mercury and methylmercury in lake ice were determined for the first time. The percentage of methylmercury (MeHg%) and ice-water partition coefficient were analyzed. The pollution situation and health risk were evaluated by single factor pollution index. The results show that the ice body and water body of Wuliangsuhai are not polluted by mercury and methylmercury, but some sampling points in the sediment are slightly polluted. The mercury content in sediment is negatively correlated with the ice thickness, and the methylmercury content in water is positively correlated with the methylmercury content in sediment, but negatively correlated with the ice thickness. The migration ability of methylmercury in ice-water system is stronger than that of mercury. The MeHg% of water in ice period is higher than that in non-freezing period, which is different from other lakes without ice sheet. The results show that in the dynamic equilibrium of methylation and demethylation in the high-latitude lake water, the methylation is higher in the ice period than in the non-freezing period due to the influence of light intensity, while the mercury in the non-freezing period is more susceptible to the demethylation.

Topography Controls Variability in Circumpolar Permafrost Thaw Pond Expansion

AbstractOne of the most conspicuous signals of climate change in high‐latitude tundra is the expansion of ice wedge thermokarst pools. These small but abundant water features form rapidly in depressions caused by the melting of ice wedges (i.e., meter‐scale bodies of ice embedded within the top of the permafrost). Pool expansion impacts subsequent thaw rates through a series of complex positive and negative feedbacks which play out over timescales of decades and may accelerate carbon release from the underlying sediments. Although many local observations of ice wedge thermokarst pool expansion have been documented, analyses at continental to pan‐Arctic scales have been rare, hindering efforts to project how strongly this process may impact the global carbon cycle. Here we present one of the most geographically extensive and temporally dense records yet compiled of recent pool expansion, in which changes to pool area from 2008 to 2020 were quantified through satellite‐image analysis at 27 survey areas (measuring 10–35 km2 each, or 400 km2 in total) dispersed throughout the circumpolar tundra. The results revealed instances of rapid expansion at 44% (15%) of survey areas. Considered alone, the extent of departures from historical mean air temperatures did not account for between site variation in rates of change to pool area. Pool growth was most clearly associated with upland (i.e., hilly) terrain and elevated silt content at soil depths greater than one meter. These findings suggest that, at short time scales, pedologic and geomorphologic conditions may exert greater control on pool dynamics in the warming Arctic than spatial variability in the rate of air temperature increases.

Temporal Variation Analysis in Clean Ice Glacier of Annapurna Basin

Glaciers of the Himalayas are the storehouse of fresh water. The impacts of climate change, mainly the melting of snow cover have been noticed in Nepal’s Himalayas. These changes have local as well as regional implications on water resources, and at global level on the sea level rise. This study is carried out to analyze the temporal variation of glacier retreat in the Annapurna valley from 2000 to 2020 using remote sensing technology. It is a multi-step process and involves the computation of several mathematical indices for glaciers based on the spectral properties of Landsat imagery. The final outcome is the delineation of Clean Ice Glacier (CIG) area of Annapurna basin for the years 2000, 2010 and 2020. The findings from this study reveal that the glaciers of Annapurna basin are shrinking more rapidly in the recent years than before. The decrease in CIG area coupled with the increase in the CIG number clearly indicate that the glaciers are being fragmented into smaller parts creating several disconnected ice bodies. Monitoring the dynamics of glaciers along with their trend analysis is crucial for strengthening the climate change mitigation and adaptation strategies. Key Words: Clean Ice Glacier, Temporal Variation, Annapurna Basin, Remote Sensing, Climate Change

Exploring ice melting dynamics in beverageware

The ice-melting process inside water-filled beverageware is studied experimentally, theoretically, and numerically. An ice body is immersed in warm fresh water in different-shaped glass cups. The ice body eventually melts due to heat transfer from the warmer fluid to the ice. As the ice melts and cools the surrounding fluid, it promotes complex time-dependent laminar flows characterized by a vertical downward jet beneath the ice body and rotating convective cells in the fluid domain. Experimental results obtained through dye visualization, particle image velocity, and local temperature measurements show that the size and number of the rotating cells, jet velocity, and melting time of the ice depend significantly on the shape of the beverageware. A one-dimensional analytical solution reproduces qualitatively the hydrodynamical and thermal boundary layers close to the ice body. Further, a two-dimensional numerical model correctly captures the main features of the experimental observations.

The velocity extraction and feature analysis of glacier surface motion in the Gongar region based on multi-source remote sensing data

The movement of glaciers plays a crucial role in environmental and geological processes, significantly influencing the formation and dynamics of ice bodies. This study leverages feature tracking technology to analyze optical and Synthetic Aperture Radar (SAR) remote sensing imagery, specifically GF-1 optical images and GF-3, Sentinel-1 SAR images, captured during the 2020 to 2021 ablation season in Gongar. The aim was to quantify glacier surface velocities and to evaluate the comparative effectiveness of different remote sensing modalities in capturing these dynamics. Our findings indicate a strong consistency in the spatial distribution of glacier surface velocities derived from diverse remote sensing data sources, with high-precision optical imagery (GF-1) yielding the most accurate velocity measurements, followed by Sentinel-1 SAR data. Notably, large glaciers in Gongar exhibited rapid movements, with an average velocity of 0.16 m/d, primarily at elevations between 4,500 and 6,500 m. The fastest velocities were recorded at approximately 4,500 m elevation. Glaciers with inclines ranging from 10° to 60° displayed the highest velocities within the 20°–30° slope range. It was observed that glaciers on the southeast slope moved faster, exhibiting the highest average surface velocity, in contrast to those on the west slope, which moved more slowly. The surface velocity of the ice tongue region of Krayaylak Glacier that the largest glacier in Pamir, was observed to be lower than 0.6 m/d, indicating a slow movement speed. The study also reveals that the effectiveness of different remote sensing data in detecting glacier velocity in Gongar, with high-resolution data more accurately capturing surface velocities in melting areas or those with slower movement. This study underscores the importance of multi-source remote sensing data in understanding glacier dynamics and contributes valuable insights into the mechanisms driving glacier movements.

Post-LGM glaciomarine processes revealed by inner shelf sedimentary facies analysis (Terra Nova Bay, Western Ross Sea, Antarctica)

Understanding the depositional processes on the inner shelf of Antarctica is a significant challenge. This difficulty arises from the heterogeneity of sediment sources, their poor preservation potential due to the advance and retreat cycles of ice bodies, and the impact of relatively strong bottom currents generated by high density contrasts in the water column. These factors contribute to the overall complexity of the glacio-influenced marine environment, particularly below present-day floating ice shelves in correspondence of areas draped in sediments related to Late Pleistocene-Holocene glacial variations. These locations provide crucial information for reconstructing past glacial dynamics driven by global changes.In this study, we present an analysis of glaciomarine deposits collected from the Western Ross Sea, offshore Mario Zucchelli Station, in a protected indentation of the Victoria Land Coast that hosts the Terra Nova Bay polynya. We conducted multi-proxy analyses on three sediment cores sampled from selected seafloor morphological units associated with fluctuations of the grounded ice, which preserve sedimentary facies representative of this distinctive depositional environment.We identified and described six depositional facies, characterized by diagnostic sedimentological, textural and geochemical patterns. Direct observations were integrated with high-resolution geophysical data and geomorphological seafloor analysis. Our findings highlight a Late Pleistocene-Holocene depositional sequence linked to fluctuations in grounded ice, with unconformities and sedimentary patterns potentially related to climatic variations driving ice advances and retreats.

Behavioural tendencies of the last British–Irish Ice Sheet revealed by data–model comparison

ABSTRACTIntegrating ice‐sheet models with empirical data pertaining to palaeo‐ice sheets promotes advances in the models used in sea‐level predictions and can improve our understanding of past ice‐sheet behaviour. The large number of empirical constraints on the last British–Irish Ice Sheet make it ideal for model–data comparison experiments. Here, we present an ensemble of 600 model simulations, which are compared with data on former ice‐flow extent, flow geometry and deglaciation timing. Simulations which poorly recreate data were ruled out, allowing us to examine the remaining physically realistic simulations which capture the ice sheets' behavioural tendencies. Our results led to a novel reconstruction of behaviour in the data‐poor region of the North Sea, insights into the ice stream, potential ice‐shelf and readvance dynamics, and the potential locations of peripheral ice caps. We also propose that the asynchronous behaviour of the British–Irish Ice Sheet is a consequence of the geography of the British Isles and the merging and splitting of different bodies of ice through saddle merger and collapse. Furthermore, persistent model–data mismatches highlight the need for model development, especially regarding the physics of ice–ocean interactions. Thus, this work highlights the power of integrating models and data, a long‐held aim of palaeoglaciology.

First records of a new Europe&amp;rsquo;s southernmost glacier found in Southern Albania

Several perennial snow and ice bodies have been recently studied and monitored in three mountain massifs across the Balkan Peninsula: Prokletije (Northern Albania), Durmitor (Montenegro) and Pirin (Bulgaria), the two glacierets in the Pirin Mountains until soon considered as southernmost of their kind in Europe. In September 2022 a relatively large snow field (about 1.5 ha) was discovered and described for a first time in the glacial cirque Gryka e Kazanit in the N&amp;euml;mer&amp;ccedil;ka Mountains of Southern Albania. The snow accumulation lies on 1550&amp;ndash;1650 m a.s.l. below a vertical limestone cliff with a height of almost 1000 m. The site was visited again in November 2023, when the snow field diminished its size to less than 1 ha. At the same time, multi-annual firn layers were exposed under the last year snow, with depth at least several metres, and indications were observed of ice, buried in the debris cover below. Newest findings indicate that the studied snow-firn body is a glacieret similar to those found in the Pirin Mountains. On a longer-term, nine perennial snow/firm bodies on the Balkans resemble small glaciers rather than snow and ice patches at least under current climatic conditions. Situated on 40&amp;deg;08&amp;prime; Northern latitude, the newly discovered Nem&amp;euml;r&amp;ccedil;ka Glacieret is nominated to be the southernmost glacier in Europe.

The last remnants of the Italian Apennine glaciers: 3-D modeling of the Lower Calderone Glacieret by the IDW spatial interpolation of GPR data

Abstract We present a quantitative ground-penetrating radar (GPR) analysis of the Lower Calderone Glacieret to highlight the recent evolution of one of the southernmost glacial systems in Europe. The Upper and Lower Calderone Glacierets are the last two perennial ice bodies in the Apennine Mountains (Italy), and their continuous monitoring is important for glaciology, hydrology and climate science. We applied a proprietary auto-picking algorithm to track reflections accurately and objectively within three pseudo-3-D GPR data sets that were acquired over the Lower Glacieret in different years. After the time-to-depth conversion, the basal reflections were projected onto the normal versors of a 3-D topographic model of the survey area, at the different GPR trace positions. We then applied an Adjusted Inverse-Distance Weighted Spatial Interpolation method to extrapolate the ice-bedrock interface within the areas not directly covered by the GPR profiles and compare it with the topographic surface to recover the glacieret volume. In this paper, we critically examine the accuracy of the reconstructed models, including possible issues related to the challenging survey areas, such as local artifacts in the interpolated interface caused by irregular GPR coverage. We further discuss the various advantages of the implemented procedure with respect to more traditional glacier monitoring techniques.

Localised sublimation under cometary dust mantles

Observations of cometary surfaces have indicated that the amount of exposed surficial water ice is insufficient to supply the measured water production rates within the inner solar system. The measured water production rates are also a small fraction of that which would arise from freely subliming pure water ice bodies of similar surface area. A plausible mechanism, given the now well-established, high porosity of comets is that water ice is subliming below the visible surface with the produced gas escaping through the pores in a non-subliming hot dust matrix. If this process leads to an additional heating of the evolving gas, this may provide an elegant explanation for the temperature of the gas required to match measured terminal velocities. We investigate this process using a series of numerical models based on the Direct Simulation Monte Carlo (DSMC) method for rarified gas dynamics. We show that inhomogeneities in the source are not evident in the flow field once the thickness of the porous layer reaches a specific size and that lateral flow through the porous layer (parallel to the surface) can broaden the apparent source size when the source is small and isolated. The temperatures of the gas flow at the visible surface can be significantly increased and will respond to the temperature distribution within the non-volatile porous layer. The influence of the structural properties of the porous layer (how the porous layer is mechanically constructed) is shown to have only limited influence on the final gas parameters at the surface.

FIRST DIRECT RADIOCARBON DATING (22–27 CAL KA BP) OF MASSIVE ICE AT THE MECHIGMEN AND LAVRENTIYA BAYS COAST, EASTERN CHUKOTKA

ABSTRACTThe Eastern Chukotka is considered a unique permafrost region where massive ice bodies are widespread. However, the origin and age of these ice formations are often discussed. The age of the massive ice of Chukotka was established for the first time using AMS 14C dating. It was revealed that three massive ice bodies on the coast of Mechigmen Bay were formed at the end of the Late Pleistocene: a) near the Akkani site, 21,612 to 22,147 cal BP; b) near the Lavrentiya settlement, 27,553 cal BP; and c) near the Lavrentiya settlement, 22,193 cal BP. Stable isotope values in the studied massive ice vary in a rather wide range by about 10‰ for δ18O values (from –14.8‰ to –24.5‰) and about 75‰ for the δ2H values (from –116‰ to –191‰). The studied massive ice bodies are of intrasedimental genesis and formed epigenetically during the final stage of MIS2 (22–27 cal ka BP).

The complex basal morphology and ice dynamics of the Nansen Ice Shelf, East Antarctica

Abstract. Ice shelf dynamics and morphology play an important role in the stability of floating bodies of ice by driving fracturing that can lead to calving, in turn impacting the ability of the ice shelf to buttress upstream grounded ice. Following a 2016 calving event at the Nansen Ice Shelf (NIS), East Antarctica, we collected airborne and ground-based radar data to map ice thickness across the shelf. We combine these data with published satellite-derived data to examine the spatial variations in ice shelf draft, the cause and effects of ice shelf strain rates, and the possibility that a suture zone may be channelizing ocean water and altering patterns of sub-ice-shelf melt and freeze-on. We also use our datasets to assess limitations that may arise from relying on hydrostatic-balance equations applied to ice surface elevation to determine ice draft morphology. We find that the Nansen Ice Shelf has a highly variable basal morphology driven primarily by the formation of basal fractures near the onset of the ice shelf suture zone. This morphology is reflected in the ice shelf strain rates but not in the calculated hydrostatic-balance thickness, which underestimates the scale of variability at the ice shelf base. Enhanced melt rates near the ice shelf terminus and in steep regions of the channelized suture zone, along with relatively thin ice in the suture zone, appear to represent vulnerable areas in the NIS. This morphology, combined with ice dynamics, induce strain that has led to the formation of transverse fractures within the suture zone, resulting in large-scale calving events. Similar transverse fractures at other Antarctic ice shelves may also be driven by highly variable morphology, and predicting their formation and evolution could aid projections of ice shelf stability.

Experimental Study on Mixed-Mode (I–II) Fracture Toughness of Freshwater Ice

In recent years, the issue of aircraft icing has gained widespread recognition. The breaking and detachment of dynamic ice can pose a threat to flight safety. However, the shedding and fracture mechanisms of dynamic ice are unclear and cannot meet the engineering needs of ice-shedding hazard assessment. Therefore, studying the fracture toughness of ice bodies has extremely important practical significance. To address this issue, this article uses a centrally cracked Brazilian disk (CCBD) specimen to measure the pure mode I toughness and pure mode II fracture toughness of freshwater ice at different loading rates. The mixed-mode (I–II) fracture characteristics of ice are discussed, and the experimental results are compared and analyzed with the theoretical values of the generalized maximum tangential stress (GMTS) criterion considering the influence of T-stress. The results indicated that as the loading rate increases, the pure mode I toughness and pure mode II fracture toughness of freshwater ice decrease, and the fracture toughness of freshwater ice is more sensitive to the loading rate. In terms of fracture criteria, the theoretical value of the ratio of pure mode II fracture toughness to pure mode I fracture toughness based on the GMTS criterion is in good agreement with the experimental value, while the theoretical value based on the maximum tangential stress (MTS) criterion deviates significantly from the experimental value, indicating that the GMTS criterion considering the influence of T-stress can better predict the experimental results.

Numerical Simulation of Icebreaking by Underwater-Explosion Bubbles and Compressed-Gas Bubbles Based on the ALE Method

Icebreaking by using underwater explosion bubbles and compressed high-pressure gas bubbles has gradually become an effective icebreaking method. In order to compare the damaging effect of these two methods on the ice body, a fluid–structure coupling model was established based on the arbitrary Lagrangian–Eulerian (ALE) method and a series of calculations were carried out. The morphological changes of underwater explosion bubbles and compressed gas bubbles at the same energy under the free surface; the changes of flow load near the rigid wall; and the damage caused to the ice plate were studied and compared. The damage effect of the ice plate was analyzed by detecting the number of failure elements of the ice plate, and the optimum standoff distance was found. For an ice plate with a radius of 0.19 m and a thickness of 0.15 m, the optimum standoff distance of the compressed gas bubbles with 120 J is 0.03 m, and the optimum standoff distance of the TNT with 120 J is 0.02875 m. The similarities and differences of the two sources of bubbles on ice plate damage were summarized.

Modelling the historical and future evolution of six ice masses in the Tien Shan, Central Asia, using a 3D ice-flow model

Abstract. In the Tien Shan, few modelling studies exist that examine in detail how individual ice bodies are responding to climate change. Nonetheless, earlier research demonstrated that the glacier response to climate change in this mountain range is heterogeneous. Here, we use several measurements and reconstructions of the ice thickness, surface elevation, surface mass balance, and ice temperature to model in depth six different ice bodies in the Kyrgyz Tien Shan: five valley glaciers and one ice cap. The selected ice masses are located in different sub-regions of the Tien Shan with different climatic and topographic settings, and they are all characterized by detailed recent glaciological measurements. A three-dimensional higher-order thermomechanical ice-flow model is calibrated and applied to simulate the evolution of the ice masses since the end of the Little Ice Age (1850) and to make a prognosis of the future evolution up to 2100 under different Coupled Model Intercomparison Project Phase 6 (CMIP6) shared socioeconomic pathway (SSP) climate scenarios. The results reveal a strong retreat of most of the ice masses under all climate scenarios, albeit with notable variations in both timing and magnitude. These can be related to the specific climate regime of each of the ice bodies and their geometry. Under a moderate warming scenario, the ice masses characterized by a limited elevation range undergo complete disappearance, whereas the glaciers with a larger elevation range manage to preserve some ice at the highest altitudes. Additionally, our findings indicate that glaciers that primarily receive precipitation during the late spring and summer months exhibit a more rapid retreat in response to climate change, while the glaciers experiencing higher precipitation levels or more winter precipitation remain for a longer duration. Projections concerning the overall glacier runoff reveal that the maximum water discharge from the ice masses is expected to occur around or prior to the middle of the 21st century and that the magnitude of this peak is contingent upon the climate scenario, with a higher warming scenario resulting in a higher peak.

Shear wave effects in hydroacoustic recordings of the Comprehensive Nuclear-Test-Ban Treaty International Monitoring System

The hydroacoustic (HA) component of the Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System (IMS) comprises six stations with triplets of moored hydrophones suspended in the SOFAR channel and five near-shore seismometer stations for T-phase detection. Understanding the conversion between compressional and elastic waves at the crust-ocean boundary or at large bodies of ice can contribute to better identification and association of arrivals. In this talk, examples recorded by the IMS HA network are presented with a view to stimulating discussion and further analysis: (i) T-phases from the September 2017 announced DPRK underground nuclear test recorded by the hydrophones of HA11 (Wake Island); (ii) a “precursor” southerly arrival at HA04 (Crozet Islands), associated with the hydroacoustic anomaly related to the loss of the Argentine submarine ARA San Juan, which is inter alia compatible with a Lamb wave propagating through the Antarctic ice-sheet; (iii) T-phases from earthquakes along the Nazca subduction zone scattered horizontally by the Juan Fernandez sea-mounts and recorded by HA03 (Chile); and (iv) conversion of signals from distant underwater explosions at the crust-ocean boundary near IMS T-stations. Benchmark studies to assess the accuracy of spectral element model setups previously used for scenarios (iv) would be particularly desirable.

Everest South Col Glacier did not thin during the period 1984–2017

Abstract. The South Col Glacier is a small body of ice and snow (approx. 0.2 km2) located at the very high elevation of 8000 m a.s.l. (above sea level) on the southern ridge of Mt. Everest. A recent study by Potocki et al. (2022) proposed that South Col Glacier is rapidly losing mass. This is in contradiction to our comparison of two digital elevation models derived from aerial photographs taken in December 1984 and a stereo Pléiades satellite acquisition from March 2017, from which we estimate a mean elevation change of 0.01 ± 0.05 m a−1. To reconcile these results, we investigate some aspects of the surface energy and mass balance of South Col Glacier. From satellite images and a simple model of snow compaction and erosion, we show that wind erosion has a major impact on the surface mass balance due to the strong seasonality in precipitation and wind and that it cannot be neglected. Additionally, we show that the melt amount predicted by a surface energy and mass balance model is very sensitive to the model structure and implementation. Contrary to previous findings, melt is likely not a dominant ablation process on this glacier, which remains mostly snow-covered during the monsoon.