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Although fluctuations in ice sheet surface mass balance lead to seasonal and interannual elevation changes, it is unclear if they are resolved differently by radar and laser satellite altimeters. We compare methods of computing elevation change from CryoSat‐2 and ICESat‐2 over the Greenland Ice Sheet to assess their consistency and to quantify recent change. Solutions exist such that interannual trends in the interior and the ablation zone agree to within −0.2 ± 1.5 and 3.3 ± 6.0 cm/yr, respectively, and that seasonal cycle amplitudes within the ablation zone agree to within 3.5 ± 38.0 cm. The agreement is best in the north where the measurements are relatively dense and worst in the southeast where the terrain is rugged. Using both missions, we estimate Greenland lost 196 ± 37 km3/yr of volume between 2010 and 2022 with an interannual variability of 129 km3/yr. Plain Language Summary: The polar ice sheets are reacting to climate warming. Changes in their height can be used to study changes in their snowfall, surface melting, glacier flow, and sea level contribution. Although satellite altimeters are able to detect changes in ice sheet height, it is not clear whether these changes are sensed differently by laser and radar systems. Using four years of coincident measurements recorded by ESA's CryoSat‐2 and NASA's ICESat‐2, we show that radar‐laser differences at the ice sheet scale are, in fact, a small proportion (<10%) of the changes in height that are taking place. This means that either system can be used with confidence to study the effects of climate change on the polar ice sheets. At smaller spatial scales, the remaining differences are still important and should be investigated further so that we can understand their causes. Key Points: Greenland Ice Sheet elevation change between 2018 and 2022 from CryoSat‐2 and ICESat‐2 was −11.4 ± 0.8 and −11.7 ± 1.3 cm/yr, respectivelyAblation zone seasonal cycle amplitude between 2018 and 2022 from CryoSat‐2 and ICESat‐2 was 62.9 ± 26.5 and 59.4 ± 24.4 cm, respectivelyVolume change between 2010 and 2022 was −196 ± 37 km3/yr with an interannual variability of 129 km3/yr [ABSTRACT FROM AUTHOR]

Glaciers in the Arctic have lost considerable mass during the last two decades. About a third of the glaciers by area drains into the ocean, yet the mechanisms and drivers governing mass loss at glacier calving fronts are poorly constrained in part due to few long-term glacier-ocean observations. Here, we combine a detailed satellite-based record of calving front ablation for Austfonna, the largest ice cap on Svalbard, with in-situ ocean records from an offshore mooring and modelled freshwater runoff for the period 2018-2022. We show that submarine melting and calving occur almost exclusively in autumn for all types of outlet glaciers, even for the surging and fast-flowing glacier Storisstraumen. Ocean temperature controls the observed frontal ablation, whereas subglacial runoff of surface meltwater appears to have little direct impact on the total ablation. The seasonal warming of the offshore waters varies both in magnitude, depth and timing, suggesting a complex interplay between inflowing Atlantic-influenced water at depth and seasonally warmed surface water in the Barents Sea. The immediate response of frontal ablation to seasonal ocean warming suggests that marine-terminating glaciers in high Arctic regions exposed to Atlantification are prone to rapid changes that should be accounted for in future glacier projections. This study links autumn glacier front mass loss at Austfonna (2018-2022) to ocean warming rather than surface melt, highlighting the sensitivity of Svalbard's glaciers to ocean forcing. [ABSTRACT FROM AUTHOR]

The Belvedere glacier is an intensively studied glacier in the Italian Alps on the east face of the Monte Rosa, which is currently undergoing a fast deglaciation connected to various slope failures and Glacial Lake Outburst Floods. Measurements of the terminus position have been carried out since the 1920s. Since 2000, more attention has been paid to this area due to the occurrence of large mass movements and a surge-type event. In this review, research articles and various reports dealing mainly with glacier dynamics, rock and ice avalanches, Glacial Lake Outburst Floods, and other hazardous processes were considered. Aerial photogrammetry, Unmanned Aerial Vehicles, satellite stereo-processing and several terrestrial approaches (laser scanning, geophysics, measurements of near-surface heat flow, ablation stakes and camera-lapse) provided a base for quantifying the ongoing processes. Despite efforts based on the comparison of Digital Elevation Models, this review shows that the evolution of the Belvedere glacier in terms of ice volume is still partially unknown due to the low temporal frequency of aerial surveys, technical limitations of the Unmanned Aerial Vehicles used, and the fact that most studies focus only on the lower part of the glacier. The hazardous supraglacial Effimero lake that appeared during the surge-type event has been well documented, and interventions to mitigate potential risks were put in place, but the trigger of the event and the evolution of the lake basin have not yet been clarified. Mass wasting and outburst floods are mainly documented in the grey literature. The degradation of permafrost was suggested to be the driver of rock and ice avalanches, including one of the largest ice avalanches in the Alps, which occurred in 2005. In summary, the Belvedere Glacier and the surrounding rock walls have experienced repeated slope failures, an incident of surge and several outburst floods. Despite regular monitoring, a clear picture of its behavior due to the changing climate is still unknown. This review is intended to pave the way for further integrative studies. [ABSTRACT FROM AUTHOR]

Bacterial, fungal, and algal communities that colonize aquatic systems on glacial ice surfaces mediate biogeochemical reactions that alter meltwater composition and affect meltwater production and storage. In this study, we sought to improve understanding of microbial communities inhabiting the shallow aquifer that forms seasonally within the ice surface of a glacier's ablation zone (i.e., the weathering crust aquifer). Using a metagenomic approach, we compared gene contents of microbial assemblages in the weathering crust aquifer (WCA) of the Matanuska Glacier (Alaska, USA) to those recovered from supraglacial features and englacial ice. High abundances of Pseudomonadota, Cyanobacteriota, Actinomycetota, and Bacteroidota were observed across all samples, while taxa in class Gammaproteobacteria were found at significantly higher abundances in the weathering crust aquifer. The weathering crust aquifer samples also contained higher abundances of Dothideomycetes and Microbotryomyetes; fungal classes commonly observed in snow and other icy ecosystems. Phylogenetic analysis of 18S rRNA and rbcL gene sequences indicated high abundances of algae in the WCA that are closely related (> 98% and > 93% identity, respectively) to taxa of Ancylonema (Streptophyta) and Ochromonas (Ochrophyta) reported from glacial ice surfaces in Svalbard and Antarctic sea ice. Many functional gene categories (e.g., homeostasis, cellular regulation, and stress responses) were enriched in samples from the weathering crust aquifer compared to those from proximal englacial and supraglacial habitats, providing evidence for ecological specialization in the communities. The identification of phagotrophic phytoflagellate taxa and genes involved in mixotrophy implies that combined phototrophic and heterotrophic production may assist with persistence in the low light, low energy, and ephemeral conditions of the weathering crust environment. The compositional and functional differences we have documented indicate distinct microbial distributions and functional processes occur in the weathering crust aquifer environment, and we discuss how deciphering these nuances is essential for developing a more complete understanding of ecosystem biogeochemistry in supraglacial hydrological systems. [ABSTRACT FROM AUTHOR]

Assessing changes of the mass balance in the Antarctic ice sheet in the context of global warming is a key focus in polar study. This study analyzed the spatiotemporal variation in the Antarctic ice sheet's mass balance, both as a whole and by individual basins, from 2003 to 2016 and from 2018 to 2022 using GRACE RL06 data published by the Center for Space Research (CSR) and ERA-5 meteorological data. It explored the lagged relationships between mass balance and precipitation, net surface solar radiation, and temperature, and applied the random forest method to examine the relative contributions of these factors to the ice sheet's mass balance within a nonlinear framework. The results showed that the mass loss rates of the Antarctic ice sheet during the study periods were −123.3 ± 6.2 Gt/a and −24.8 ± 52.1 Gt/a. The region with the greatest mass loss was the Amundsen Sea in West Antarctica (−488.8 ± 5.3 Gt/a and −447.9 ± 14.7 Gt/a), while Queen Maud Land experienced the most significant mass accumulation (44.9 ± 1.0 Gt/a and 30.0 ± 3.2 Gt/a). The main factors contributing to surface ablation of the Antarctic ice sheet are rising temperatures and increased surface net solar radiation, each showing a lag effect of 1 month and 2 months, respectively. Precipitation also affects the loss of the ice sheet to some extent. Over time, the contribution of precipitation to the changes in the ice sheet's mass balance increases. [ABSTRACT FROM AUTHOR]

Glacier pattern changes directly indicate variability in local climatic circumstances. The present study dealt with the proposition and estimation of spatiotemporal glacier movement using a synthetic aperture radar-derived polarimetric tracking method which revealed improved estimates over four selected large tributary-bearing glaciers (Siachen, Bara Shigri, Gangotri, and Zemu) in the Indian Himalayas. The average estimated velocities in 2021–2022 for the four glaciers were 0.13, 0.06, 0.08 and 0.09 m/day. The thick debris cover hindered the movement temporally in the middle and lower reaches of the glaciers. The effect of meltwater influx along the tributary confluence zone was also witnessed over the glaciers. Comparison and validation with the US National Aeronautics and Space Administration (NASA) Inter-mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE) products has shown the utility of the proposed method in studying the contributions of active feeding tributaries of the glaciers in the ablation zone. [ABSTRACT FROM AUTHOR]

We developed automated ablation stakes to measure colocated in situ changes in relative glacier-surface elevation and climatological drivers of ablation. The designs, refined over 10 years of development and deployments, implement open-source hardware and common building materials. The ablation stakes record distance to the snow/ice surface, air temperature and relative humidity every 1–15 min. Using these high-frequency data, we demonstrate that melt factors calculated using standard melt-rate vs temperature regressions converge over averaging windows of approximately 12 h or greater. Furthermore, we evaluate an integral approach to estimating temperature-index melt factors for ablation. In a test case on Glaciar Perito Moreno, Argentina, this integral approach reveals an overall positive-degree-day melt factor of 7.5 mm w.e. $^\circ$ C−1 d−1. We describe four deployments with iteratively improved designs and provide a list of materials required to construct an automated ablation stake. [ABSTRACT FROM AUTHOR]

In the Himalaya, ice thickness data are limited, and field measurements are even scarcer. In this study, we employed the GlabTop model to estimate ice reserves in the Jhelum (1.9 ± 0.6 km3) and Drass (2.9 ± 0.9 km3) sub-basins of the Upper Indus Basin. Glacier ice thickness in the Jhelum ranged up to 187 ± 56 m with a mean of ~24 ± 7 m, while the Drass showed ice thickness up to 202 ± 60 m, with a mean of ~17 ± 5 m. Model results were validated using Ground Penetrating Radar measurements across four profiles in the ablation zone of the Kolahoi glacier in the Jhelum and nine profiles across the Machoi glacier in the Drass sub-basin. Despite underestimating ice-thickness by ~10%, the GlabTop model effectively captured glacier ice-thickness and spatial patterns in most of the profile locations where GPR measurements were taken. The validation showed high correlation coefficient of 0.98 and 0.87, low relative bias of ~ −13% and ~ −3% and a high Nash–Sutcliffe coefficient of 0.94 and 0.93 for the Kolahoi and Machoi glaciers, respectively, demonstrating the model's effectiveness. These ice-thickness estimates improve our understanding of glacio-hydrological, and glacial hazard processes over the Upper Indus Basin. [ABSTRACT FROM AUTHOR]

The negative surface mass balance of glaciers and ice caps under a warming climate impacts local ecosystems, influencing the volume and timing of water flow in local catchments while also contributing to global sea level rise. Peripheral glaciers distinct to the Greenland ice sheet respond faster to climate change than the main ice sheet. Accurate assessment of surface mass balance depends on in situ observations of near-surface climate and ice ablation, but very few in situ observations of near-surface climate and ice ablation are freely available for Greenland's peripheral glaciers. The transect of three automated weather and ablation stations on the peripheral A. P. Olsen Ice Cap in northeast Greenland is an example of these much needed data. The transect has been monitored since 2008, and in 2022, the old weather and ablation stations were replaced by a new standardized setup. In order to ensure comparable data quality of the old and new monitoring station setups, it is necessary to re-evaluate the data collected between 2008 and 2022. This paper presents the fully reprocessed near-surface climate and ablation data from the A. P. Olsen Ice Cap transect from 2008 to 2022, with a focus on data quality and the usability in ice ablation process studies. The usability of the data is exemplified by the data in an energy balance melt model for two different years. We show that the inherent uncertainties in the data result in an accurate reproduction of ice ablation for just one of the two years. A transect of three automatic ablation and weather stations of this length is unique to Greenland's peripheral glaciers, and it has a broad scale of usage from input to climate reanalysis and detailed surface ablation studies. The dataset can be downloaded at 10.22008/FK2/X9X9GN. [ABSTRACT FROM AUTHOR]

This study proposes an additional feature of optical coherence tomography (OCT) as a guidance system for laser surgery, aiming to enhance ablation efficiency during laser osteotomy. A long-range Bessel-like beam OCT system is integrated with an Er:YAG laser. The signal sensitivity of the OCT system is measured under various conditions encountered during laser osteotomy. The results demonstrate that the OCT sensitivity decreases from 87.53 dB to 79.54 dB and 68.93 dB in the presence of debris and water, respectively. These findings highlight the potential application signal sensitivity of OCT as a criterion for detecting the accumulation of water and debris, which could lead to a reduction in ablation efficiency during laser osteotomy using Er:YAG laser. [ABSTRACT FROM AUTHOR]

Albedo plays a critical role in the mass balance of a glacier, as it affects its ablation. In this work, the remotely sensed albedo dynamics of Turbio and Pedregoso glaciers of the Villarrica Volcano were assessed, after the occurrence of a large-magnitude eruptive event in 2015, which partially covered them of tephras. The albedo was derived from eight ASTER (Advanced Spaceborn Thermal Emission and Reflection Radiometer) satellite images, acquired on near-anniversary summer dates before, during and after the mentioned event (2009-2022). The temporal behavior of the ex-post albedo of both studied glaciers tended to predominantly decrease, especially in their ablation zones. They are subject to greater surface exposure of the tephra deposits, in response to the cyclical melting/sublimation experienced during the summer by the snowpack succeed in cover them during the rest of the year. This decrease reached its maximum value in 2002, likely due to the extremely singular warmth and drought recorded in the previous year in the study area. It is expected that these results will contribute to understand the ex-post dynamics of the albedo in the study area, in terms of its magnitude and pervasiveness over time. This may provide valuable information for tracking and prospecting the mass balances of both studied glaciers. [ABSTRACT FROM AUTHOR]

The Last Glacial Maximum (LGM) was characterised by huge ice sheets covering the Northern Hemisphere, especially over North America, and by its cold climate. Previous authors have performed numerical simulations of the LGM to better understand coupled climate–ice sheet systems. However, the results of such simulations are sensitive to many model parameters. Here, we perform a 200-member ensemble of simulations of the North American and Greenland ice sheets and climate of the LGM with a coupled ice sheet–atmosphere–slab ocean model (FAMOUS-BISICLES) to explore sensitivities of the coupled climate–ice system to 16 uncertain parameters. In the ensemble of simulations, the global mean surface temperature is primarily controlled by the combination of parameters in the large-scale condensation scheme and the cumulus convection scheme. In simulations with plausible LGM global mean surface temperatures, we find that the albedo parameters have only a small impact on the Greenland ice volume due to the limited area of surface ablation associated with the cold climate. Instead, the basal sliding law controls the ice volume by affecting ice transport from the interior to the margin. On the other hand, like the Greenland ice sheet in future climate change, the LGM North American ice sheet volume is controlled by parameters in the snow and ice albedo scheme. Few of our simulations produce an extensive North American ice sheet when the global temperature is above 12 °C. Based on constraints on the LGM global mean surface temperature, the ice volume and the southern extent of the North American ice sheet, we select 16 acceptable simulations. These simulations lack the southern extent of ice compared to reconstructions, but they show reasonable performance on the ice sheet configuration and ice streams facing Baffin Bay and the Arctic Ocean. The strong sensitivities of the North American ice sheet to albedo at the LGM may imply a potential constraint on the future Greenland ice sheet by constraining the albedo schemes. [ABSTRACT FROM AUTHOR]

This study investigates the temporal processes of suprapermafrost groundwater (SPG)‐supplied streamflow in alpine permafrost regions, aiming to fill the gap in understanding this process from a water‐age perspective. Precipitation, streamflow, and SPG samples were collected from the Three‐Rivers Headwaters Region (TRHR). We defined the physical meaning of Fyw (the young water fraction) of the SPG and calculated it for the first time. The results showed that in the TRHR, the SPG mean travel time (MTT) was 159 days, and approximately 46.4% of SPG was younger than 77 days, whereas the streamflow MTT was 342 days, and approximately 12.2% of the streamflow was younger than 97 days. The correlation analysis revealed that various climatic factors played dominant roles in the recharge time variations of the SPG‐supplied streamflow within the TRHR. The SPG recharge rate did not significantly affect the streamflow Fyw; however, the thickness of the active layer ultimately controlled the SPG transit time distribution. Regression analysis further demonstrated the nonlinear impact of precipitation, average temperature, and average freezing days on SPG Fyw, which is closely related to seasonal freeze–thaw heat conduction and groundwater heat advection in the active layer. During the initial ablation period, the streamflow was primarily recharged by young SPG, resulting in a short‐tail travel time distribution. Our findings provide valuable insights into runoff generation and concentration processes in permafrost regions and have important implications for water resource management. Plain Language Summary: This article investigates the temporal process of suprapermafrost groundwater (SPG) (groundwater within the active layer above the permafrost) recharging streamflow in alpine permafrost regions, aiming to fill the gap from this perspective. We collected samples of SPG, streamflow, and precipitation from the Three‐Rivers Headwaters Region and calculated the water age of SPG. We found that approximately half of the SPG contributing to streamflow is young water, however, the young water fraction of the streamflow is lower than the global average for rivers. We analyzed the environmental factors controlling water age and identified climatic conditions, active layer thickness, and relief amplitude as the primary influencing factors in permafrost regions. Based on analyses of permafrost thermal and hydrological conditions, we determined that streamflow was primarily recharged by the young SPG during the initial ablation period. Our results provide important insights for studying the runoff generation and concentration processes in permafrost regions and for water resource management strategies. Key Points: The mean travel time of suprapermafrost groundwater (SPG) in study area was 159 days, and ∼46.4% of the water was younger than 77 daysClimate conditions, active layer thickness, and relief amplitude are the primary controlling factors for the SPG ageThe recharge of streamflow by young SPG primarily occurs during the initial ablation period [ABSTRACT FROM AUTHOR]

Ice caps are important water resources for Iceland and are threatened by climate change. Despite their importance and vulnerability, the geodetic glacier mass balance estimate for the recent decade lacks a high‐resolution result. To address this gap, we first co‐registered the 2012–2021 ArcticDEM (v4) strips with ICESat‐2 points acquired over off‐ice areas and evaluated the accuracy of the co‐registered DEMs. We then applied a per‐pixel weighted liner regression to the multi‐temporal ArcticDEM strips and generated a high‐resolution (2 m) glacier surface elevation change rate for six major Icelandic ice caps. Based on these estimates we calculated the geodetic mass balance. Additionally, we estimated the seasonal relative surface elevation changes using ICESat‐2 ATL06 data for the 2019 to 2021 period. The results showed the co‐registered ArcticDEM strips exhibit good accuracy, with a standard deviation of 1.15 m across the Icelandic ice cap regions. Between 2012 and 2021, Icelandic ice caps experienced a state of mass loss, with a surface elevation change rate of −0.57 ± 0.21 m/a, corresponding to a mass loss of −0.51 ± 0.02 m w.e/a. Spatial variability in glacier surface elevation changes among different Icelandic ice caps ranges −0.19 m/a to −0.75 m/a. The Langjökull ice cap exhibited the most severe glacier mass loss at −0.68 ± 0.006 m w.e/a. Furthermore, our observations indicate a change in seasonal trends occurred across all six ice caps from 2019 to 2021. Specifically, the glacier surface thickening decreased during the accumulation period, while the thinning rate increased during the ablation period. These findings highlight that ArcticDEM v4 strips provide new insights into the mass balance of Icelandic glaciers and will aid in making future water management decisions. Moreover, the high‐resolution surface elevation topography and change rates provided in this study may contribute to an improved understanding of the influence of glacier dynamics on glacier change. [ABSTRACT FROM AUTHOR]

The Indian Summer Monsoon (ISM) and meltwater from the Himalayan are the two most important sources of water in the Indian subcontinent. However, the impact of ISM on Himalayan glaciers and subsequent stream hydrology remains largely unknown. To provide new insight into the impact of rainfall on glacial hydrology, here we present hydro‐meteorological and time‐series observations of meltwater stable water isotope compositions from the snout of the Chorabari glacier in the Upper Ganga Basin, Central Himalayas across the ablation season corresponding to 2019. We observe that rainfall events (>2 mm d−1) on the glacier enhance discharge driven by ice meltwater in River Mandakini. Energy balance calculations reveal that one of the drivers behind enhanced ice meltwater contribution could be rain‐induced melting of the glacier where rainfall on the ice surface melts the glacier producing up to 13% of the total discharge at the glacier snout. Further, rainfall on glacier surface have other control on glacial processes—for example, snow metamorphism, ice flow dynamics such as short‐term acceleration in ice speed flow, and reorganization of the englacial and subglacial drainage network—that are poorly studied and needs further investigation. We conclude rainfall events on the glacier have a complex control on mountain hydrology. This study, therefore, provides an interpretative framework that calls for additional assessments of the direct and indirect impact of rainfall in glacial hydrology. Plain Language Summary: Understanding the drivers of elevated ice meltwater runoff in glacier‐fed Himalayan streams is critically important in constraining the role of climate change in glacial hydrology. The conventional thinking of elevated ice meltwater runoff in Himalayan rivers is mainly attributed to global warming. However, in this study, we find that rain events on the glacier are an additional driver of enhanced ice meltwater discharge in the glacier‐fed Himalayan streams. The additional flux of ice meltwater can be explained by the reorganization of the englacial and subglacial drainage network during rainfall events and/or rain‐induced melting of the glacier ice where raindrops falling on the ice surface are releasing sensible and latent heat by englacial cooling and freezing of rain, thereby raising ice temperatures to the melting point, in result, enhanced ice meltwater contributions. As the number of extreme rainfall events and their associated catastrophes has increased in recent decades, the observed causal relationship between ISM and enhanced ice meltwater contributions in the Himalayas is critical to better manage and predict important environmental problems such as floods in the Himalayas. Key Points: An isotope mixing model was developed to quantify the contributions of rain, ice, and snow meltwater to the total river dischargeWe show heavy monsoonal rainfall triggers the melting of glacier ice resulting in enhanced ice meltwater discharge in streamsWe conclude rainfall events have complex controls on glacial hydrology/processes [ABSTRACT FROM AUTHOR]

Snow cover ablation within the Ohio River Basin (ORB) plays an important role in regional hydroclimatology, while also representing a potential hazard during large and rapid events. Rain‐on‐snow ablation is a particular challenge, where runoff rates are typically enhanced due to the dual inputs of snowmelt and liquid precipitation. Here, we present a 40‐year climatology of snow ablation events frequency, intensity, and timing for the ORB using a 4‐km gridded snow‐water‐equivalent dataset, focusing on the relative proportion of events caused by rain‐on‐snow and changes over time. Spatial patterns of snow ablation frequency and intensity mirror that of seasonal snowfall totals, with higher (lower) values in the northern and eastern (southern) portions of the basin. Rain‐on‐snow events represent approximately 40% of all ablation events within the basin and result in approximately 24%–25% more snow‐water‐equivalent loss than non‐rain‐on‐snow events, plus an additional 3–12 mm of liquid precipitation per event on average. Peak frequency of ablation and rain‐on‐snow events occurs in late winter and early spring, similar to that of the surrounding region. Over time, the frequency of ablation and rain‐on‐snow events has decreased in the northern and eastern portions of the basin, in some cases by as much as 30%. Trends in event magnitudes were more isolated but decreased across portions of central IN, northern KY, eastern OH and northern WV. Additionally, the magnitude of precipitation during rain‐on‐snow events has increased across the region, extending from northern KY into western PA by over 100% in many cases. Broadly, we find tendencies towards fewer events with less snow loss but more liquid precipitation that suggest complicated impacts to the hydroclimatology warranting further investigation. [ABSTRACT FROM AUTHOR]

The Vanj River Basin contains a dynamic glacier, the Medvezhiy glacier, which occasionally poses a danger to local residents due to its surging, flooding, and frequent blockages of the Abdukahor River, leading to intense glacial lake outburst floods (GLOF). This study offers a new perspective on the quantitative assessment of glacier surface velocities and associated lake changes during six surges from 1968 to 2023 by using time-series imagery (Corona, Hexagon, Landsat), SRTM elevation maps, ITS_LIVE, unmanned aerial vehicles, local climate, and glacier surface elevation changes. Six turbulent periods (1968, 1973, 1977, 1989–1990, 2001, and 2011) were investigated, each lasting three years within a 10–11-year cycle. During inactive phases, a reduction in the thickness of the glacier tongue in the ablation zone occurred. During a surge in 2011, the flow accelerated, creating an ice dam and conditions for GLOF. Using these datasets, we reconstructed the process of the Medvezhiy glacier surge with high detail and identified a clear signal of uplift in the surface above the lower glacier tongue as well as a uniform increase in velocities associated with the onset of the surge. The increased activity of the Medvezhiy glacier and seasonal fluctuations in surface runoff are closely linked to climatic factors throughout the surge phase, and recent UAV observations indicate the absence of GLOFs in the glacier's channel. Comprehending the processes of glacier movements and related changes at a regional level is crucial for implementing more proactive measures and identifying appropriate strategies for mitigation. [ABSTRACT FROM AUTHOR]

Present study focuses on the utilization of Earth observation satellite-04 (EOS-04) synthetic aperture radar (SAR) data for maintaining the continuity of the first Indian radar imaging satellite (RISAT)-1 SAR derived products along with exploring the potential of capability of the improved sensor over mountain and polar cryospheric region. Backscattering coefficient (σ0) of various snow and ice features over mountain and polar cryosphere have been analysed to understand the interaction mechanism using C-band SAR data. EOS-04 is able to pick up the spatio-temporal variability of SAR backscatters over accumulation and ablation zone of the glacier due to melt-freeze cycles, and observations were in accordance with variation in elevations over the glacier surface. When analysed for Drang-Drung glacier, wet snow zone was found to be prominently centered around 5500 m elevation zone, having sigmanaught backscatter lower than –10 dB in the ablation months, whereas percolation zone was observed at more than 6000 m elevation with higher sigma-naught backscatter of around –4 dB and above as winter started setting in. EOS-04 also showed the potential to classify various polar ice features based on backscattering signature using HH (H, horizontal) (σ0), HV (V, vertical) (σ0) and normalized difference polarization ratio index (NDPRI) respectively. EOS-04 data have been used to implement approaches to retrieve wet snow cover and set up of Weather Research and Forecasting Model Hydrological Modelling System (WRF hydro) model for snow melt runoff studies, interaction mechanism of snow and ice, snow/ice facies extraction, ice shelf monitoring, sea ice properties and sea ice advisory for Indian scientific expedition to Antarctica. Enrichment of EOS-04 data, suitable for cryosphere studies, will be employed to retrieve parameters such as snowpack properties, elevation, ice surface velocities over mountain and polar region, and to further improve comprehensive understanding on regional and global frozen ice dynamics. [ABSTRACT FROM AUTHOR]

Most climatic and glaciological processes exhibit internal variability, which is omitted from many ice sheet model simulations. Prior studies have found that climatic variability can change ice sheet sensitivity to the long-term mean and trend in climate forcing. In this study, we use an ensemble of simulations with a stochastic large-scale ice sheet model to demonstrate that variability in frontal ablation of marine-terminating glaciers changes the mean state of the Greenland Ice Sheet through noise-induced drift. Conversely, stochastic variability in surface mass balance does not appear to cause noise-induced drift in these ensembles. We describe three potential causes for noise-induced drift identified in prior statistical physics literature: noise-induced bifurcations, multiplicative noise, and nonlinearities in noisy processes. Idealized simulations and Reynolds decomposition theory show that for marine ice sheets in particular, noise-induced bifurcations and nonlinearities in variable ice sheet processes are likely the cause of the noise-induced drift. We argue that the omnipresence of variability in climate and ice sheet systems means that the state of real-world ice sheets includes this tendency to drift. Thus, the lack of representation of such noise-induced drift in spin-up and transient ice sheet simulations is a potentially ubiquitous source of bias in ice sheet models. [ABSTRACT FROM AUTHOR]

Inheritance from prior exposure often complicates the interpretation of terrestrial cosmogenic nuclide (TCN) inventories in glaciated terrain. Lochnagar, a mountain in eastern Scotland, holds a clear geomorphological record of corrie glaciation and the thinning of the last Scottish ice sheet over the last ~15 ka. Yet attempts to date the main stages in deglaciation after sampling of 21 granite boulders for 10Be, 26Al and 14C from corrie moraines, an ice sheet lateral moraine and boulder spreads revealed widespread, but variable, TCN inheritance. Only the youngest boulder ages fit within the range of expected deglaciation ages. To identify the sources of geological uncertainty, we provide simple models of ice cover duration and erosion histories for plateau, corrie and strath landscape domains, identify the variable nuclide inheritance that derives from different sources for boulders in these domains, and outline the effects of rotation, splitting and erosion of boulders during glacial transport. The combined effects increase clustering around arbitrary mean TCN values that exceed deglaciation ages. A further implication is that boulders have survived beneath overriding ice sheets. Such boulder trapping at Lochnagar may have resulted from topographic controls on katabatic winds and surface ablation acting on a thinning, cold‐based ice sheet. [ABSTRACT FROM AUTHOR]

An increase in winter air temperature can amplify snowmelt and sublimation in mountain regions with implications to water resources and ecological systems. Winter Warm Spells (WWS) are defined as a winter period (December to February, DJF) of at least 3 consecutive days with daily maximum temperature anomaly above the 90th percentile (using a moving‐average of 15 days between 2001 and 2013). We calculate WWS for every 4‐km grid cell within an atmospheric model over western North America to characterize WWS and analyze snow ablation and their changes in a warmer climate. We find that days with ablation during WWS represent a small fraction of winter days (0.6 days), however, 49% of total winter ablation (33.4 mm/DJF) occurs during WWS. Greater extreme ablation rates (99th percentile) occur 18% more frequently during WWS than during non‐WWS days. Ablation rates during WWS in humid regions are larger (9 mm d−1) than in dry regions (7 mm d−1) in a warmer climate, which can be explained by differences in the energy balance and the snowpack's cold content. We find that warmer (0.8°C), longer (1.8 days) and more frequent (3.7 more events) WWS increase total winter ablation (on average 109% or 18 mm/DJF) in a warmer climate. Winter melt during WWS in warm and humid places is expected to increase about 3 times more than in the cold and dry region. This study provides a comprehensive description of WWS and their impact on snowpack dynamics, which is relevant to reservoir operations and water security. Plain Language Summary: Extreme maximum winter temperatures (Winter Warm Spells, WWS) can affect the snow in winter by increasing snowmelt, with consequences for mountain water supplies. In this study we quantify snowpack response to WWS in the mountains of western North America and its sensitivity to a warmer future climate using numerical models, observations, and statistical tools. We find that 49% of snow lost in winter happens during WWS, despite having only 0.6 days with WWS per winter. Across the mountains, the humid climatic regions are more affected by WWS than arid regions. We show that snowpack ablation during WWS will increase in a warmer climate, which will put more stress on reservoir and water security planning. Key Points: Winter Warm Spells account for 49% of snowpack winter ablation (16.5 mm), despite only representing 0.6 days on averageHistorical Winter Warm Spells increase in frequency (3.7 more events), duration (1.8 days) and magnitude (0.8°C) in a warmer climateWinter snow ablation driven by melt (93.6%) is expected to increase in a warmer climate (147%), especially in humid regions [ABSTRACT FROM AUTHOR]

A significant portion of surface melt on the Greenland Ice Sheet (GrIS) is due to dark ice regions in the ablation zone, where solar absorption is influenced by the physical properties of the ice, light absorbing constituents (LACs), and the overlying crustal surface or melt ponds. Earth system models (ESMs) typically prescribe the albedo of ice surfaces as a constant value in the visible and near‐infrared spectral regions. This work advances ESM ice radiative transfer modeling by (a) incorporating a physically based radiative transfer model (SNow, ICe and Aerosol Radiation model Adding‐Doubling Version 4; SNICAR‐ADv4) into the Energy Exascale Earth System Model (E3SM), (b) determining spatially and temporally varying bare ice physical properties over the GrIS ablation zone from satellite observations to inform SNICAR‐ADv4, and (c) assessing the impacts on simulated GrIS albedo and surface mass balance associated with modeling of more realistic bare ice albedo. GrIS‐wide bare ice albedo in E3SMv2 is overestimated by ∼4% in the visible and ∼7% in the near‐infrared wavelengths compared to the Moderate Resolution Imaging Spectroradiometer. Our bare ice physical property retrieval method found that LACs, ice crustal surfaces, and melt ponds reduce visible albedo by 30% in the bare ice region of the GrIS ablation zone. The realistic bare ice albedo reduces surface mass balance by ∼145 Gt, or 0.4 mm of sea‐level equivalent between 2000 and 2021 compared to the default E3SM. This work highlights the importance of simulating bare ice albedo accurately and realistically to improve our ability to quantify changes in the GrIS surface mass and radiative energy budgets. Plain Language Summary: A large portion of melt from the Greenland Ice Sheet (GrIS) comes from regions with dark bare ice, because dark ice absorbs more incoming sunlight than regions with bright snow. Earth System Models, which simulate changes in the Earth's climate and the impacts of these changes, prescribe the reflectivity of these dark ice regions as a constant. This work shows that treating bare ice as though it has a constant reflectivity is not a good approximation, because the dark ice regions change as the winter snowpack melts and impurities accumulate on the ice surface. This work improves how the reflectivity of bare ice is calculated by incorporating a new physical model into the Energy Exascale Earth System Model and uses satellite measurements to inform the new model. The improvements made here show that previous methods overestimate the reflectivity of bare ice, meaning they underestimate how much light is absorbed and how much melt comes from the bare ice regions on the GrIS. It is important to have more accurate methods for determining the reflectivity of bare ice regions, as this will ultimately lead to improved estimates of sea‐level rise. Key Points: The Energy Exascale Earth System Model version 2 bare ice albedo scheme overestimates the exposed bare ice albedo on the Greenland Ice Sheet by an average of 5%Satellite observations can infer the optically relevant bare ice properties to predict albedo over the Greenland Ice Sheet ablation zoneRealistic spatio‐temporally varying ice albedo in the Greenland Ice Sheet ablation zone increases surface melt by ∼6 Gt/year from 2000 to 2021 [ABSTRACT FROM AUTHOR]

The detection of Martian polar ice cap change patterns is important for understanding their effects on driving Mars's global water cycle and for regulating atmospheric circulation. However, current Martian ice cap identification using optical remote sensing data mainly relies on visual interpretation, which makes it difficult to quickly extract ice caps from multiple images and analyze their fine-scale spatiotemporal variation characteristics. Therefore, this study proposes an automatic Martian polar ice cap extraction algorithm for remote sensing data and analyzes the dynamic change characteristics of the Martian North Pole ice cap using time-series data. First, the automatic Martian ice cap segmentation algorithm was developed based on the ice cap features of high reflectance in the blue band and low saturation in the RGB band. Second, the Martian North Pole ice cap was extracted for the three Martian years MY25, 26, and 28 using Mars Orbiter Camera (MOC) Mars Daily Global Maps (MDGMs) data, which had better spatiotemporal continuity to analyze its variation characteristics. Lastly, the spatiotemporal variation characteristics of the ice cap and the driving factors of ice cap ablation were explored for the three aforementioned Martian years. The results indicated that the proposed automatic ice cap extraction algorithm had good performance, and the classification accuracy exceeded 93%. The ice cap ablation boundary retreat rates and spatiotemporal distributions were similar for the three years, with approximately 105 km2 of ice cap ablation for every one degree of areocentric longitude of the Sun (Ls). The main driving factor of ice cap ablation was solar radiation, which was mainly related to Ls. In addition, elevation had a different effect on ice cap ablation at different Ls in the same latitude area near the ablation boundary of the ice cap. [ABSTRACT FROM AUTHOR]

As an important hydrological ecosystem component, the glacier basin has great significance for climate and environment, and it is also linked to regional water sustainability. In this paper, the sampling and isotope analysis of glacial ice, ice-melt water, river water (river midstream and river downstream), groundwater (spring), and precipitation were carried out in a hydrological year of the Mingyong Glacier basin, which is located at the Meili Snow Mountains, Southeastern Tibetan Plateau. At the same time, the hydrograph separation of the recharge sources of the lower mountain pass is studied. The results show that the range of δD, δ18O, and d-excess (deuterium excess) in natural water bodies are significantly different, and the precipitation is the most obvious. The high values of δD and δ18O in the water samples all appeared in spring and summer, and the low values appeared in autumn and winter, while glacial ice showed opposite trends. Meanwhile, the local meteoric water line (LMWL) of the Mingyong Glacier basin is δD = 8.04δ18O + 13.06. The End-Member Mixing Analysis (EMMA) was adopted to determine the sources proportion of river water (river downstream) according to the δD, δ18O, and d-excess ratio relationships. The results showed that the proportion of ice-melt water, groundwater, and precipitation in the ablation period was 80.6%, 17.2%, and 2.2% as well as 19.2%, 73.1%, and 7.7% in the accumulation period, respectively. Ice-melt water has a higher conversion recharge rate to groundwater and indirectly recharges river water, especially in nonmonsoon seasons. In other words, the main recharge source of river water in the lower reaches of the Mingyong Glacier basin during the ablation period is ice-melt water. In the accumulation period, the main recharge source of river water in the lower reaches of the Mingyong Glacier basin is groundwater, while nearly half of the recharge of groundwater comes from ice-melt water. Therefore, regardless of the ablation period or the accumulation period, ice-melt water is sustainable and important to this region. [ABSTRACT FROM AUTHOR]

The termini of Icelandic glaciers are highly dynamic environments. Pronounced changes in frontal ablation in recent years have consequently changed ice dynamics. In this study, we reveal the inter‐seasonal dynamics of the Kvíárjökull ablation zone and proglacial zone using ArcticDEM and Sentinel‐2 images acquired between 2011 and 2021 and intra‐seasonal dynamics with repeated UAV surveys during summer 2021. Average glacier surface velocity in the ablation zone ranged from 51 m year−1 in 2015 up to 199 m year−1 in 2018, with maxima within the axial zone of the glacier and minima on the glacier edges. Coincidentally, and in accordance with glacier retreat/advance, the ice‐marginal proglacial lake fluctuated in its area, and we interpret that it was also a key factor in the development of the glacier terminus morphology. A complex spatial pattern of glacier surface elevation changes, including thickening in the frontal true left margin of the terminus, is interpreted to be due to variable subglacial topography, relatively fast ice flow from the accumulation zone and an insulating effect of glacier surface debris cover. In contrast, the true right (southern) part of the glacier terminus experienced thinning and retreat/disintegration also during the 2021 summer season, which we attribute to enhanced frontal ablation connected to the intrusion of lake water into the crevassed glacier terminus. Overall, this study suggests that where glaciers are developing ice‐marginal lakes complex patterns of glacier dynamics and mass loss can be expected, which will confound understanding of the short‐term evolution of these environments. [ABSTRACT FROM AUTHOR]

Understanding the microscopic variability of impurities in glacier ice on a quantitative level has importance for assessing the preservation of paleoclimatic signals and enables the study of macroscopic deformational as well as dielectric ice properties. Two‐dimensional imaging via laser‐ablation‐inductively‐coupled‐plasma‐mass‐spectrometry (LA‐ICP‐MS) can provide key insight into the localization of impurities in the ice. So far, these findings are mostly qualitative and gaining quantitative insights remains challenging. Recent advances in LA‐ICP‐MS high‐resolution imaging now allow ice grains and grain boundaries to be resolved individually. These resolutions require new adequate quantification strategies and, consequently, accurate calibration with matrix‐matched standards. Here, we present three different quantification methods, which provide a high level of homogeneity at the scale of a few tens of microns and are dedicated to imaging applications of ice cores. One of the proposed methods has a second application, offering laboratory experiments to investigate the displacement of impurities by grain growth, with important future potential to study ice‐impurity interactions. Standards were analyzed to enable absolute quantification of impurities in selected ice core samples. Calibrated LA‐ICP‐MS maps indicate similar spatial distributions of impurities in all samples, while impurity levels vary distinctly: Higher concentrations were detected in glacial periods and Greenland, and lower levels in interglacial periods and samples from central Antarctica. These results are consistent with ranges from complementary meltwater analysis. Further comparison with cm‐scale melting techniques calls for a more sophisticated understanding of the ice chemistry across spatial scales, to which calibrated LA‐ICP‐MS maps now contribute quantitatively. Plain Language Summary: Compared to the large amount of information relating to paleoclimate signals reconstructed from cm‐scale impurity measurements on ice cores, knowledge about the spatial variability of impurities at the micro‐scale is extremely sparse—and becomes even more rare once quantitative datasets are concerned. However, there is an increasing demand for quantitative data for assessing the preservation of paleoclimatic signals and for the study of macroscopic deformational as well as dielectric ice properties in ice flow modeling and remote sensing. Two‐dimensional imaging via laser‐ablation‐inductively‐coupled‐plasma‐mass‐spectrometry (LA‐ICP‐MS) has shown great potential in this context, but so far, gaining reliable quantitative results for micro‐scale imaging has not been possible. Here, we present new quantification strategies that finally allow accurate calibration using ice standards. We carefully discuss the pros and cons of each method, apply the calibration to different samples from Greenland and Antarctica, and deliver the first calibrated LA‐ICP‐MS impurity maps at 40 μm resolution. Our results are consistent with bulk measurements performed on melted samples. The calibrated LA‐ICP‐MS maps will be essential for further comparison with bulk meltwater analysis, which may ultimately deliver an improved understanding of paleoclimate signals stored in deep ice. Key Points: This study presents new quantification strategies for two‐dimensional micro‐scale impurity imaging on ice cores with laser‐ablation‐inductively‐coupled‐plasma‐mass‐spectrometry (LA‐ICP‐MS)Calibrated LA‐ICP‐MS maps reveal similar spatial distributions of impurities in all ice core samples, while concentrations vary distinctlyWe developed a method to investigate the displacement of impurities by grain growth and to study ice‐impurity interactions in the laboratory [ABSTRACT FROM AUTHOR]

Mountain snowpack forecasting relies on accurate mass and energy input information to the snowpack. For this reason, coupled snow-atmosphere models, which downscale input fields to the snow model using atmospheric physics, have been developed. These coupled models are often limited in the spatial and temporal extent of their use by computational constraints. In addressing this challenge, we introduce HICARsnow, an intermediate-complexity coupled snow-atmosphere model. HICARsnow couples two physics-based models of intermediate complexity to enable basin-scale snow and atmospheric modeling at seasonal time scales. To showcase the efficacy and capability of HICARsnow, we present results from its application to a high-elevation basin in the Swiss Alps. The simulated snow depth is compared throughout the snow season to aerial LiDAR data. The model shows reasonable agreement with observations from peak accumulation through late-season melt-out, representing areas of high snow accumulation due to redistribution processes, as well as melt patterns caused by interactions between radiation and topography. HICARsnow is also found to resolve preferential deposition, with model output suggesting that parameterizations of the process using surface wind fields only may be inappropriate under certain atmospheric conditions. The two-way coupled model also improves surface air temperatures over late-season snow, demonstrating added value for the atmospheric model as well. Differences between observations and model output during the accumulation season indicate a poor representation of redistribution processes away from exposed ridges and steep terrain, and a low-bias in albedo at high elevations during the ablation season. Overall, HICARsnow shows great promise for applications in operational snow forecasting and studying the representation of snow accumulation and ablation processes. [ABSTRACT FROM AUTHOR]

During the ablation season, active microbial communities colonise large areas of the Greenland Ice Sheet surface and produce dissolved organic matter (DOM) that may be exported downstream by surface melt. Meltwater flow through the bare ice interfluvial area, characterized by a porous weathering crust, is slow (~ 10-2 m d-1), meaning that it presents a potential site for photochemical and/or microbial alteration of supraglacial DOM. Transformations of supraglacial DOM during transport through the supraglacial drainage system remain unexplored, limiting our understanding of supraglacial DOM inputs to downstream subglacial and coastal ecosystems. Here, we employ negative-ion electrospray ionization 21 tesla Fourier transform ion cyclotron resonance mass spectrometry to catalogue the molecular composition of DOM in supraglacial dark ice, weathering crust meltwater, and supraglacial stream water sampled in a hydrologically connected supraglacial micro- catchment to address this knowledge gap. Dark ice DOM contained significantly more aromatic (25 ± 3 %) and less biolabile (13 ± 4 %) DOM than weathering crust meltwater (3 ± 0 and 50 ± 0 %, respectively), pointing to retention of DOM on the ice surface and microbial, as well as photochemical alteration of DOM during transit through the supraglacial drainage system. These findings have implications for our understanding of supraglacial biogeochemical cycling, highlighting the importance of including the weathering crust photic zone when assessing supraglacial inputs to subglacial and downstream ecosystems. [ABSTRACT FROM AUTHOR]

The volcano-sedimentary unit in the Bafq-Saghand metallogenic province (BSMP) of Central Iran hosts various types of iron ore bodies including Fe-oxides with jaspilite beds, Mn-dominated iron lenses, magnetite-apatite lenses, and massive magnetite-apatite deposits. The Fe-oxides with jaspilite beds and Mn-dominated iron lenses have limited outcrops and show volcano-sedimentary features in the field. The main features are the presence of syngenetic submarine rhyolite-hosted magnetite, lamination and bedding of iron ore body, jaspilite and dropstone. Volcano-sedimentary origin is testified by magnetite composition showing affinity to BIF and positive Eu and negative Ce anomaly. Magnetite-apatite lenses and massive magnetite-apatite deposits that having spatio-temporal correlation form the main economically important deposits. They have magmatic to high-temperature hydrothermal field characteristics (lava flow-like ore bodies, the presence of degassing tubes in ore bodies, occurrence of brecciated texture and developed Na-Ca metasomatism). Mineral composition (enrichment of LREE, magnetite and apatite negative Eu anomaly and Co/Ni < 1 in pyrites) is in agreement with magmatic and high temperature hydrothermal origin. We propose a hydrous and oxidizing mantle derived iron-rich basic magma that formed in an extensional post-collisional setting for origin of Kiruna-type IOA ore bodies of the BSMP. Fe-oxides with jaspilite beds and Mn-dominated iron lenses resulted from degassing or eruption of iron-rich magma during Ediacaran in a submarine environment. However, magnetite-apatite lenses and massive magnetite-apatite deposits formed from an Early Cambrian magmatic-hydrothermal transition system from a magnetite-crystal mush zone. [ABSTRACT FROM AUTHOR]

Recent observations revealed the existence of ice slabs and aquifers on the Greenland ice sheet (GrIS). Both affect the ice sheet's hydrology: ice slabs facilitate runoff and aquifers modulate drainage to the bed. However, their climatic drivers and history remain unclear, as most observations cover only two decades. Here, we present a model simulation of the evolution of GrIS ice slabs and aquifers (1980–2020), evaluated using radar measurements. The results show that accumulation, melt and rain rates are good predictors for the spatial distribution of ice slabs and aquifers. Both features were already present in the late 1980s, and their extent remained relatively constant until the beginning of this century, after which increased melt led to their expansion. We show that almost any transect from the coast to the ice‐sheet interior will cross either an ice slab region, or an aquifer, or both. Plain Language Summary: The Greenland ice sheet is covered by a layer of old, porous snow called firn, which has the capacity to prevent surface melt runoff. The firn can however, form thick ice slabs or store large amounts of water underground. These change the fate of surface melt by respectively enhancing runoff and draining water to the ice sheet's bed. While observations have shown where these phenomena occur, it is still unknown what the exact atmospheric conditions are that lead to their formation. Here, we tackle this problem using computer simulations. Our results show that the amount of snowfall, melt and rain determine whether ice slabs or aquifers can form. The results also suggest that ice slabs and aquifers are more abundant than previously assumed, and that their observed expansion started only in the early 2000s, and they will continue to expand if the climate gets warmer and melt and rain become more abundant. Key Points: Accumulation, melt and rain are good predictors of ice slab and firn aquifer locationsThe expansion of modeled ice slabs and aquifers on the Greenland ice sheet started in the early 2000sWe show that, in between the ablation zone and the accumulation zone, there are always ice slabs and/or aquifers present [ABSTRACT FROM AUTHOR]

The reduction in the area and volume of glaciation in all mountain regions of the Earth has strongly accelerated for the last decades. In this work, we analysed the trends of the main climatic parameters which caused the glacier recession in the Kamchatka Peninsula. It was shown that the glaciers of the northern part of the Sredinny Range decreased by 125 km2 (35.6%) from 1950 to 2016–2017. The average rate of their reduction in the period from 2002 to 2016–2017 (1.45%/year) increased approximately 4.3 times compared to the period 1950–2002 (0.34%/year). The greatest reduction is observed in small glaciers with an area of less than 0.1 km2 and in glaciers with southeastern and southern expositions. On the Kronotsky Peninsula, the glacier area reduction for 1957–2019 was equal to 32.1 km2 (35.6%), and the rates were almost the same in the periods of 1957–2000 (0.61%/year) and 2000–2019 (0.67%/year). According to the data of weather stations and ERA5 reanalysis, it was shown that, in the ablation (summer) period the warming rate was minimal (0.3°C/10 years) and in the accumulation period a significant decrease in precipitation (5%–10%/10 years) was revealed in some areas. At the same time, a significant increase in the radiation balance was revealed in the warm season along with a tendency in downward shortwave radiation increase for the last two decades due to a decrease in cloud amount. These trends are in good agreement with the growth of the geopotential height over the North Pacific during the warm season in the 21st century, and with the growth of velocity divergence in the middle troposphere and the intensification of downward air movements. All this confirms an increase in anticyclone frequency in the warm season, which could be the cause of a radiation balance increase and, consequently, an increase in glacier ablation. [ABSTRACT FROM AUTHOR]

Blowing snow sublimation is an important boundary layer process in polar regions and is the major ablation term in the surface mass balance (SMB) of the Antarctic ice sheet. In this study, we update the blowing snow model in the Regional Atmospheric Climate Model (RACMO), version 2.3p3, to include, among other things, the effect of blowing snow sublimation in the prognostic equations for temperature and water vapour. These updates are necessary to remove undesired numerical artefacts in this version's modelled blowing snow transport fluxes. Specifically, instead of a uniformly discretised ice particle radius distribution used in the previous version of the model which limited the maximum ice particle radius to ≤ 50 μ m, we use a non-uniformly discretised ice particle radii to include all relevant ranges of radii between 2 to 300 μ m without any additional computational overhead. The updated model results are compared against the meteorological observations from site D47 in Adélie Land, East Antarctica. The updates alleviate the numerical artefacts observed in the previous model results and successfully predict the power-law variation of the blowing snow fluxes with wind speed while improving the prediction of the magnitude of the blowing snow fluxes. Furthermore, we obtain an average blowing snow layer depth of 230 ± 116 m at the observation site D47, which matches well with the typical values obtained from the satellite observations. A qualitative comparison of the blowing snow frequency from updated RACMO with CALIPSO satellite observations shows that RACMO successfully predicts the blowing snow frequency. For the period 2000–2010, compared to the previous model version, the contribution of integrated blowing snow sublimation is increased by 30 %, with a yearly mean of 176 ± 4 Gt yr-1. It contributes to a 1.2 % reduction in the integrated SMB of the Antarctic ice sheet compared to the previous model results. In addition, we observe significant changes in the sublimation in coastal and lower escarpment zone, indicating the these improvements to the climatology of blowing snow in Antarctica. [ABSTRACT FROM AUTHOR]

The mass loss of glaciers outside the polar ice sheets has been accelerating during the past several decades and has been contributing to global sea-level rise. However, many of the mechanisms of this mass loss process are not well understood, especially the calving dynamics of marine-terminating glaciers, in part due to a lack of high-resolution calving front observations. Svalbard is an ideal site to study the climate sensitivity of glaciers as it is a region that has been undergoing amplified climate variability in both space and time compared to the global mean. Here we present a new high-resolution calving front dataset of 149 marine-terminating glaciers in Svalbard, comprising 124 919 glacier calving front positions during the period 1985–2023 (10.5281/zenodo.10407266, Li et al., 2023). This dataset was generated using a novel automated deep-learning framework and multiple optical and SAR satellite images from Landsat, Terra-ASTER, Sentinel-2, and Sentinel-1 satellite missions. The overall calving front mapping uncertainty across Svalbard is 31 m. The newly derived calving front dataset agrees well with recent decadal calving front observations between 2000 and 2020 (Kochtitzky and Copland, 2022) and an annual calving front dataset between 2008 and 2022 (Moholdt et al., 2022). The calving fronts between our product and the latter deviate by 32 ± 65 m on average. The R2 of the glacier calving front change rates between these two products is 0.98, indicating an excellent match. Using this new calving front dataset, we identified widespread calving front retreats during the past four decades, across most regions in Svalbard except for a handful of glaciers draining the ice caps Vestfonna and Austfonna on Nordaustlandet. In addition, we identified complex patterns of glacier surging events overlaid with seasonal calving cycles. These data and findings provide insights into understanding glacier calving mechanisms and drivers. This new dataset can help improve estimates of glacier frontal ablation as a component of the integrated mass balance of marine-terminating glaciers. [ABSTRACT FROM AUTHOR]

Frontal ablation has caused 32 %–66 % of Greenland Ice Sheet mass loss since 1972, and despite its importance in driving terminus change, ocean thermal forcing remains crudely incorporated into large-scale ice sheet models. In Greenland, local fjord-scale processes modify the magnitude of thermal forcing at the ice–ocean boundary but are too small scale to be resolved in current global climate models. For example, simulations used in the Ice Sheet Intercomparison Project for CMIP6 (ISMIP6) to predict future ice sheet change rely on the extrapolation of regional ocean water properties into fjords to drive terminus ablation. However, the accuracy of this approach has not previously been tested due to the scarcity of observations in Greenland fjords, as well as the inability of fjord-scale models to realistically incorporate icebergs. By employing the recently developed IceBerg package within the Massachusetts Institute of Technology general circulation model (MITgcm), we here evaluate the ability of ocean thermal forcing parameterizations to predict thermal forcing at tidewater glacier termini. This is accomplished through sensitivity experiments using a set of idealized Greenland fjords, each forced with equivalent ocean boundary conditions but with varying tidal amplitudes, subglacial discharge, iceberg coverage, and bathymetry. Our results indicate that the bathymetric obstruction of external water is the primary control on near-glacier thermal forcing, followed by iceberg submarine melting. Despite identical ocean boundary conditions, we find that the simulated fjord processes can modify grounding line thermal forcing by as much as 3 °C , the magnitude of which is largely controlled by the relative depth of bathymetric sills to the Polar Water–Atlantic Water thermocline. However, using a common adjustment for fjord bathymetry we can still predict grounding line thermal forcing within 0.2 °C in our simulations. Finally, we introduce new parameterizations that additionally account for iceberg-driven cooling that can accurately predict interior fjord thermal forcing profiles both in iceberg-laden simulations and in observations from Kangiata Sullua (Ilulissat Icefjord). [ABSTRACT FROM AUTHOR]

Amid global warming, the timely supplementation of soil water is crucial for the effective restoration and protection of the ecosystem. It is therefore of great importance to understand the temporal and spatial variations of soil water sources. The research collected 2451 samples of soil water, precipitation, river water, ground ice, supra-permafrost water, and glacier snow meltwater in June, August, and September 2020. The goal was to quantify the contribution of various water sources to soil water in the Three-Rivers Headwater Region (China) during different ablation periods. The findings revealed that precipitation, ground ice, and snow meltwater constituted approximately 72 %, 20 %, and 8 % of soil water during the early ablation period. The snow is fully liquefied during the latter part of the ablation period, with precipitation contributing approximately 90 % and 94 % of soil water, respectively. These recharges also varied markedly with altitude and vegetation type. The study identified several influencing factors on soil water sources, including temperature, precipitation, vegetation, evapotranspiration, and the freeze–thaw cycle. However, soil water loss will further exacerbate vegetation degradation and pose a significant threat to the ecological security of the "Chinese Water Tower". It emphasizes the importance of monitoring soil water, addressing vegetation degradation related to soil water loss, and determining reasonable soil and water conservation and vegetation restoration models. [ABSTRACT FROM AUTHOR]

The martian North Polar layered deposits (NPLD) are composed of alternating water‐ice and dust‐rich layers resulting from atmospheric deposition and are key to understanding Mars climate cycles. Within these deposits are spiral troughs whose migration affects deposition signals. To understand the relationship between NPLD stratigraphy and Martian climate, we must identify modern‐day drivers of NPLD ice migration. Prevailing theory posits migration driven by upstream‐migrating bed undulations bounded by hydraulic jumps, caused by katabatic winds flowing over trough walls with asymmetric cross‐sectional relief. This is supported by trough‐parallel clouds, whose formation has been attributed to hydraulic jumps. We present a cloud atlas across the Martian north pole using ∼13,800 THEMIS images spanning ∼18 Earth years. We find trough‐parallel clouds in ∼400 images, with regions nearer to the pole having higher cloud frequency. We compare spiral trough geometry to our cloud atlas and find regions with trough‐parallel clouds often correlate with metrics associated with modern‐day sublimation‐deposition cycles (i.e., relief and asymmetry), but not always. In some regions, troughs with morphologies conducive to cloud formation have no clouds. Overall, trough geometry varies greatly across the deposits, both within and between troughs, suggesting localized differences in deposition relative to migration, varying katabatic wind intensities, differing past climatic states influencing the troughs, varying trough initiation properties, or the possibility of additional mechanisms for trough initiation and migration (e.g., in situ trough erosion). Understanding what controls trough shape variability across the NPLD and how these controls change through time and space is key when interpreting Martian paleoclimate. Plain Language Summary: The Martian North polar ice cap is composed of layers of water‐ice and dust deposited from the atmosphere, and differences in their thicknesses are thought to be the result of climate variations. Interpretations of the climate recorded in these layers can be affected by other processes that can deposit or erode ice. One process we need to understand is the migration history for the large spiraling troughs that occur across the ice cap, which tend to have asymmetric wall slopes and reliefs. The leading theory suggests that their migration is driven by ice ablation from winds that flow down the higher trough wall, and deposition (and cloud formation) when the wind hits the trough floor and decelerates. We present an updated record of cloud coverage across the ice cap using orbital images spanning ∼18 Earth years and analyze ∼3,000 trough cross‐sections to compare trough shape to cloud location. We find regions with clouds often correlate with trough shapes associated with modern‐day sublimation‐deposition cycles (wall asymmetry), but often asymmetric troughs have no clouds, or the troughs are symmetric. The fact that trough shape changes across the ice cap suggests that ice transport processes are variable and need to be considered when interpreting paleoclimate. Key Points: The spiral troughs on Mars' northern polar layered deposits (NPLD) have highly variable geometry, both within a trough and between troughsThe presence of trough‐parallel clouds, indicative of katabatic jumps and active trough migration, are regionally variable across the NPLDThe trough shape most conducive to the formation of katabatic jumps and generating clouds is not as widespread as previously suggested [ABSTRACT FROM AUTHOR]

Reconstructions of palaeo-ice stream activity provide an insight into the processes governing ice stream evolution over millennial timescales. The northwestern sector of the Laurentide Ice Sheet experienced a period of rapid retreat driven by warming during the Bølling–Allerød (14.7 – 12.9 ka) which may have contributed significantly to global mean sea level rise during this time. It therefore provides an opportunity to investigate ice sheet dynamics during a phase of rapid ice sheet retreat. Here, we classify coherent groups of ice flow parallel lineations into 326 flowsets and then categorise them as ice stream, deglacial, inferred deglacial or event type flowsets. Combined with ice marginal landforms and a new ice margin chronology (Dalton et al., 2023), we present the first reconstruction of ice flow dynamics of the northwestern Laurentide Ice Sheet at 500-year timesteps through the last deglaciation. At the local Last Glacial Maximum (17.5 ka), the ice stream network was dominated by large, marine-terminating ice streams (>1000 km long) that were fed by the Laurentide-Cordilleran ice saddle to the south and the Keewatin Ice Dome to the east. As the ice margin retreated onshore, the drainage network was characterised by shorter, land-terminating ice streams (<200 km long), with the exception of the Bear Lake and Great Slave Lake ice streams (~600 km long) that terminated in large glacial lakes. Rapid reorganisation of the ice drainage network, from predominantly northerly ice flow to westerly ice flow, occurred over ~2000 years, coinciding with a period of rapid ice sheet surface lowering in the ice saddle region. We note a peak in ice stream activity during the Bølling–Allerød that we suggest is a result of increased ablation and a steepening of the ice surface slope in ice stream onset zones and the increase in driving stresses which contributed to rapid ice drawdown. The subsequent cessation of ice stream activity by the end of the Bølling–Allerød was a result of ice drawdown lowering the ice surface profile, reducing driving stresses and leading to widespread ice stream shut-down. [ABSTRACT FROM AUTHOR]

Dark (low albedo) surface ice on the Greenland Ice Sheet enhances melting and subsequent runoff, a major mass loss contributor during the ablation season. The accumulation of both biological (e.g., glacier ice algae) and abiotic (e.g., mineral dust) light‐absorbing particulates are important darkening factors, that are potentially influenced by the duration of snow‐free, bare ice (a phenological factor), and other geo‐topographical factors such as elevation, slope, aspect and the distance from the ice margin. Here, we present the first medium‐resolution (30 m) analysis of the phenological and geo‐topographical controls on the distribution of dark ice in SE and SW Greenland from statistical analysis of data derived from a harmonized satellite albedo product and ArcticDEM. The duration of bare ice primarily controls the distribution of dark surface ice, allowing for algae growth on inland ice surfaces in particular, whereas geo‐topographical factors are only secondary controls. Plain Language Summary: Meltwater that runs off the Greenland Ice Sheet is currently the largest single glaciological contributor to global sea level rise. Recent darkening of the surface ice has contributed significantly to increased melt rates. We used medium resolution (30m) satellite data to link ice surface darkness (albedo) to the topography (elevation, slope, and aspect) of the ice sheet surface, the distance from the ice margin, and the duration of bare or snow‐free surface ice. Our analysis shows that the duration of bare ice or snow‐free conditions was the most significant factor in driving the darkening of ice. We also found that the impact of topographic factors on the ice darkening varied depending on whether abiotic or biological processes were driving the darkening. This information helps us to better explain where the ice sheet is melting fastest and to predict the loss of ice mass, particularly considering the expected increase in the area of bare, snow‐free ice in our warming climate. Key Points: The duration of snow‐free, bare ice is the primary control on the distribution of dark iceLonger durations of bare ice (median = 40 days) are prerequisites for ice to become darkSurface slope and aspect influence darkening by modulating the duration of bare ice and glacier ice algae growth [ABSTRACT FROM AUTHOR]

Tibetan Plateau (TP) is known as the water tower of Asia, and glaciers are solid reservoirs that can regulate the amount of water. Black carbon (BC), as one of the important factors accelerating glacier melting, is causing evident environmental effects in snow and ice. However, a systematical summary of the potential sources, analytical methods, distributions, and environmental effects of BC in snow and ice on the TP's glaciers is scarce. Therefore, this study drew upon existing research on snow and ice BC on glaciers of the TP to describe the detection methods and uncertainties associated with them to clarify the concentrations of BC in snow and ice and their climatic effects. The primary detection methods are the optical method, the thermal–optical method, the thermochemical method, and the single-particle soot photometer method. However, few studies have systematically compared the results of BC and this study found that concentrations of BC in different types of snow and ice varied by 1–3 orders of magnitude, which drastically affected the regional hydrologic process by potentially accelerating the ablation of glaciers by approximately 15% and reducing the duration of snow accumulation by 3–4 days. In general, results obtained from the various testing methods differ drastically, which limited the systematical discussion. Accordingly, a universal standard for the sampling and measurement should be considered in the future work, which will be beneficial to facilitate the comparison of the spatiotemporal features and to provide scientific data for the model-simulated climatic effects of BC. [ABSTRACT FROM AUTHOR]

For many ice core related scientific questions, like the analysis of fast changing climate signals, the depth resolution of conventional methods of analysis is not sufficient. In this study we present a setup of Laser Ablation Inductively Coupled Plasma – Mass Spectrometry (LA-ICP-MS) for high resolution glacier ice impurity analysis to the sub-millimetre scale. This setup enables chemical impurity ice core analysis to a depth resolution of ~ 80 μm while consuming only minimal amounts of ice. The system was used for simultaneous analysis of sodium, magnesium and aluminium incorporated in the ice structure. In a first case study within the framework of the WACSWAIN (WArm Climate Stability of the West Antarctic ice sheet in the last INterglacial) project, the method was applied to a selection of samples from Skytrain ice core (West Antarctica), on a total length of 6.7 m consisting of about 130 single samples. The main goal of this study was to use the new LA-ICP-MS method to extract meaningful climate signals on a depth resolution level beyond the limits of Continuous Flow Analysis (CFA). A comparison between low resolution CFA data and the high resolution LA-ICP-MS data reveals generally good agreement on the decimetre scale. Stacking of parallel laser measurements together with frequency analysis is used to analyse the high resolution LA-ICP-MS data on the millimetre scale. Spectral analysis revealed that despite effects of impurity accumulation in ice crystal grain boundaries, periodic concentration changes in the Skytrain ice core on the millimetre scale can be identified in ice from 26 ka BP (kilo years before present; 1950 CE) and also from the Last Interglacial (LIG). These findings can open new possibilities for climate data interpretation with respect to fast changes in the last glacial and beyond. [ABSTRACT FROM AUTHOR]

A widely spread ridge relief complex was formed by the last ice cover in the northeastern part of the Kola Peninsula. The complex belongs to the ice-marginal formations of the ice streams of the north-eastern Fennoscandian Ice Sheet. The applied morphometric research technique (including the analysis of the digital elevation model) has allowed identifying the ridge relief complex to make a sub-longitudinal belt. The belt comprises frontal and radial ridges, ridges and hills of the distal part of the belt, and complex-shaped ridges. These landforms were studied in eight outcrops and trenches. The frontal and some complex-shaped ridges consist of basal and ablation tills and glaciofluvial deposits deformed by the east- and north-eastward advancing glacier. The radial ridges composed of glaciofluvial sediments are the eskers. Glaciofluvial deposits with a thin cover of ablation and flow tills form the ridges on the distal part of the belt. They mark the limits of glacier expansion at an individual glacial stage. Some complexshaped ridges are composed only of the ablation melt-out till and formed in crevasses of dead ice massifs. The ridge relief complex shows morphological similarities with the Veiki moraine in North Sweden, Pulju moraine in Finland, and ridges of the "ice-walledlake plains" in North America. The location of the moraine ridge landforms is controlled by the topography of crystalline bedrock. During the last glaciation, the glacier retreated in several stages marked by belts of the ridge landforms. Each stage was followed by a series of oscillations corresponding to chains of frontal moraine ridges. The correlation of the ice-marginal forms in other parts of the Kola and Karelia regions allows the authors to refer them to the Neva Stage (other names are Keiva I, Syamozero), which took place in the Older Dryas Stadial. [ABSTRACT FROM AUTHOR]

The presented study aims to apply a method for monitoring the retreat of mountain glaciers in the Alpine region of the Swiss Alps, which consists of using optical satellite imagery and their spectral capabilities to observe snow and ice objects on the earth's surface. Satellite imagery with its big legacy archive dating back to 1972 for Landsat imagery, can be of big help to track and monitor the alpine glaciers retreat for long periods and serve as a database for modelling and predicting the glaciers retreat in the future. By combining different satellite data processing approaches, results have been obtained on the spatial distribution and dynamics of the Morteratsch Glacier over a period of 51 years. The focus of the study is to track the changes that have occurred along the positions of the ice front (terminus) in the glacier's ablation zone to obtain information about the glacier's dynamics during the study period. [ABSTRACT FROM AUTHOR]

Deep-sea hydrothermal vent systems are under investigation for base and precious metal exploitations. The impact of mining will depend critically on the ability of larval dispersal to connect and replenish endemic populations. However, assessing connectivity is extremely challenging, especially in the deep sea. Here, we investigate the potential of elemental fingerprinting of mollusk larval shells to discriminate larval origins between multiple hydrothermal sites in the southwest Pacific Ocean. The gastropod Shinkailepas tollmanni represents a suitable candidate as it uses capsules to hold larvae before dispersal, which facilitates sampling and ensures mineralization occurs on the site of origin. Multielemental microchemistry was performed using cutting-edge femtosecond laser ablation inductively coupled plasma mass spectrometry analysis to obtain individual measurements on 600 encapsulated larval shells. We used classification methods to discriminate the origin of individuals from 14 hydrothermal sites spanning over 3500 km, with an overall success rate of 70 %. When considering fewer sites within more restricted areas, reflecting dispersal distances reported by genetic and modeling approaches, the success rate increased up to 86 %. We conclude that individual larval shells register site-specific elemental signatures that can be used to assess their origin. These results open new perspectives to get direct estimates on population connectivity from the geochemistry of pre-dispersal shells of recently settled juveniles. [ABSTRACT FROM AUTHOR]

Efficient water resource management in glacier- and snow-dominated basins requires accurate estimates of the snow water equivalent (SWE) in late winter and spring and melt onset timing and intensity. To understand the high spatio-temporal variability of snow and glacier ablation, a spatially distributed energy balance model combining satellite-based retrievals of albedo and snow cover was applied. Incoming short-wave energy, contributing to daily estimates of melt energy, was constrained by remotely sensed surface albedo for snow-covered surfaces. Fractional snow cover was used for non-glaciated areas, as it provides estimates of snow cover for each pixel to better constrain snow melt. Thus, available daily estimates of melt energy in a given area were the product of the possible melt energy and the fractional snow cover of the area or pixel for non-glaciated areas. This provided daily estimates of melt water to determine seasonal snow and glacier ablation in Iceland for the period 2000–2019. Observations from snow pits on land and glacier summer mass balance were used for evaluation, and observations from land and glacier-based automatic weather stations were used to evaluate model inputs for the energy balance model. The results show that the interannual SWE variability was generally high both for seasonal snow and glaciers. For seasonal snow, the largest SWE (>1000 mm) was found in mountainous and alpine areas close to the coast, notably in the East- and Westfjords, Tröllaskaga, and in the vicinity of glacier margins. Lower SWE values were observed in the central highlands, flatter inland areas, and at lower elevations. For glaciers, more SWE (glacier ablation) was associated with lower glacier elevations while less melt was observed at higher elevations. For the impurity-rich bare-ice areas that are exposed annually, observed SWE was more than 3000 mm. [ABSTRACT FROM AUTHOR]

Climate warming is changing the magnitude, timing, and spatial patterns of mountain snowpacks. A warmer atmosphere may also induce precipitation phase shifts, resulting in a decreased snowfall fraction (Sf). The combination of Sf and snowpack directly influences the frequency and intensity of rain-on-snow (ROS) events, a common cause of flash-flood events in snow-dominated regions. In this work, we investigate ROS patterns and their sensitivity to temperature and precipitation changes in the Pyrenees by modeling ROS through a physically based snow model. This model is forced with reanalysis climate data for elevations of 1500, 1800, and 2400 m perturbed using a range of temperature and precipitation values consistent with 21st century climate projections. ROS patterns are characterized by their frequency, rainfall quantity, and snow ablation. The highest ROS frequency for the historical climate period (1980–2019) is found in the 2400 m zones of the southwest Pyrenees (17 d yr -1). The maximum ROS rainfall amount is detected in 1800 m areas of the southeast (45 mm d -1 , autumn), whereas the highest ROS ablation is found in the 2400 m zones of the northwest (- 10 cm d -1 , summer). When air temperature increases from 1 to 4 ∘ C compared to the historical climate period, ROS rainfall amount and frequency increase at a constant rate during winter and early spring for all elevation zones. For the rest of the seasons, non-linear responses of ROS frequency and ablation to warming are found. Overall, ROS frequency decreases in the shoulders of the season across eastern low-elevation zones due to snow cover depletion. However, ROS increases in cold, high-elevation zones where long-lasting snow cover exists until late spring. Similarly, warming induces greater ROS ablation (+ 10 % ∘ C -1) during the coldest months of the season, 2400 m elevations, and northern sectors, where the deepest snow depths are found. In contrast, small differences in ROS ablation are found for warm and marginal snowpacks. These results highlight the different ROS responses to warming across the mountain range, suggest similar ROS sensitivities in near-mid-latitude zones, and will help anticipate future ROS impacts in hydrological, environmental, and socioeconomic mountain systems. [ABSTRACT FROM AUTHOR]

Frontal ablation at tidewater glaciers, which comprises iceberg calving, submarine and subaerial melting, is a key boundary condition for numerical ice sheet models but remains difficult to measure directly in-situ. Many previous studies have quantified frontal ablation over varying spatio-temporal scales, however most use ice discharge as an approximation for frontal ablation, thereby neglecting the influence of terminus location change. Frontal ablation estimates that do account for terminus location change are spatio-temporally limited by the availability of observational data. Here, we present a processing chain to quantify frontal ablation using open-source observational data. We apply the processing chain to 49 tidewater glaciers in Greenland with reliable near-terminus bathymetry data in the BedMachine V4 dataset. Nearterminus volume change over the time period 1987 - 2020 is determined using a previously published dataset of terminus positions (TermPicks), ice thicknesses from ArcticDEM and AeroDEM, adjusted for surface elevation change over time, and bathymetry data from BedMachine v4. Assuming a vertical terminus geometry and uniform ice density, we estimate frontal ablation as the difference between mass flux towards the terminus (Mankoff et al., 2020) and mass change between consecutive observation. The frontal ablation dataset offers exciting opportunities for developing new insights into ice dynamics, including helping to improve numerical model hindcasting and projections. Lastly, we provide a processing chain that may serve as a community standard for determining frontal ablation from observational data for any tidewater glacier. [ABSTRACT FROM AUTHOR]

The negative surface mass balance of glaciers and ice caps under a warming climate impacts local ecosystems, influencing the volume and timing of water flow in local catchments, while also contributing to global sea level rise. Peripheral glaciers distinct to the Greenland ice sheet respond faster to climate change than the main ice sheet. Accurate assessment of surface mass balance depends on in-situ observations of near-surface climate and ice ablation, but very few in-situ observations of near-surface climate and ice ablation are freely available for Greenland’s peripheral glaciers. The transect of three automated weather and ablation stations on the peripheral A. P. Olsen ice cap in northeast Greenland is an example of this much needed data. The transect has been monitored since 2008, and in 2022 the old weather and ablation stations were replaced by a new standardized setup. In order to ensure comparable data quality from the old and new monitoring station setups, it was necessary to re-evaluate the data collected between 2008 and 2022. This paper presents the fully reprocessed near-surface climate and ablation data from the A. P. Olsen ice cap transect from 2008 to 2022, with a focus on data quality and the usability for ice ablation process studies. The usability and some quality issues are exemplified by using the data in an energy balance melt model for two different years. We showed that the inherent uncertainties of the data resulted in an accurate reproduction of ice ablation for just one of the two years. A transect of three automatic ablation and weather stations of this length is unique for Greenland’s peripheral glaciers and it has a broad scale of usage from input to climate reanalysis to detailed surface ablation studies. The dataset can be downloaded here: https://doi.org/10.22008/FK2/X9X9GN (Larsen and Citterio, 2023). Future refinements will be uploaded as new versions and the continuation of the transect time series are available via. [ABSTRACT FROM AUTHOR]

We describe the annual pattern of frontal ablation driven by submarine melting mechanisms at the Hansbreen terminus: these are reflected in the intensity and spatial distribution of calving events. Analysis of time-lapse images of the Hansbreen front in conjunction with oceanographic and meteorological data shows that calving intensity is driven primarily by seawater temperature. Regression analysis also highlights the importance of air temperature, which we take to be a proxy for surface ablation and subglacial discharge. This, combined with seasonal changes in ice cliff tortuosity and the increasing significance of wave motion outside the ablation season, enabled us to determine seasonal changes in the mechanisms of ice cliff undercutting by submarine melting. While submarine melting controlled by estuarine circulation primarily drives frontal ablation in summer, wave-driven melting at the waterline is more important outside the ablation season. During winter, ice cliff undercutting by melting is suspended by low seawater temperature, negligible subglacial water discharge and sea-ice cover. The most intense frontal ablation, recorded in summer, was related to higher sea temperature and vigorous estuarine circulation. [ABSTRACT FROM AUTHOR]