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Indicators for the start and end of annual break-up and freeze-up of sea ice at various coastal locations around the Arctic are developed. Relative to broader offshore areas, some of the coastal indicators show an earlier freeze-up and later break-up, especially at locations where shorefast ice is prominent. However, the trends towards earlier break-up and later freeze-up are unmistakable over the post-1979 period in synthesized metrics of the coastal break-up/freeze-up indicators.

We present an averaging algorithm for multidimensional snow stratigraphy profiles that elicits the predominant snow layering among large numbers of profiles and allows for compiling of informative summary statistics and distributions of snowpack layer properties. This creates new opportunities for presenting and analyzing operational snowpack simulations in support of avalanche forecasting.

Process-based models are frequently used to investigate the influence of climate change on lake ice cover, but an assessment of their validity at large spatial scales is currently lacking. Here, we provide a global assessment of lake ice models, comparing the models can accurately simulate the long-term change in lake ice but fail to capture the occurrence of extreme ice years. Model performance also differs across location and morphometric gradients.

As temperature increases more snow and ice melt at the surface of ice sheets. Here we use an ice dynamics and subglacial hydrology model with simplified geometry and climate forcing to study the impact of variations in melt-water on ice dynamics. We focus on the variations in length and intensity of the melt season. Our results show that a longer melt season lead to faster glaciers. However, more intense melt season reduces glaciers seasonal velocities albeit leading to higher peak velocities.

Snow avalanches cause considerable material and human damage in all mountain regions of the world. Here, we present the first model to automatically inventory avalanches at the scale of a catchment area – here the Amu Darya in Afghanistan – every year since 1990. This model called Snow Avalanche Frequency Estimation (SAFE) is available online on the Google Engine interface. SAFE has been designed to be simple and universal to use. Nearly 30,000 avalanches were detected over the 32 years studied.

Impacts of rain-on-snow (ROS) on satellite-retrieved sea ice variables remains to be fully understood. This study evaluates the impacts of ROS over sea ice on active and passive microwave data collected during the 2019–20 MOSAiC expedition. Rainfall and subsequent refreezing of the snowpack significantly altered emitted and backscattered radar energy, laying important groundwork for understanding their impacts on operational satellite retrievals of various sea ice geophysical variables.

Ice Surface Temperature (IST) products were used to develop the first multi-sensor, gap-free L4 IST product of the Greenland Ice Sheet (GIS) for 2012, when a significant melt event occurred. For the melt season, mean IST was −15 °C to −1 °C and almost the entire GIS experienced at least 1 to 5 melt days. Inclusion of the L4 IST to a surface mass budget (SMB) model, improved model performance during the key onset of the melt season, where biases are typically large.

This study compares snow depth measurements from two manual instruments and an airborne platform in a field and forest. The manual instruments’ snow depths differed by 1 to 3 cm. The airborne measurements , which do not penetrate the leaf litter, were consistently shallower than either manual instrument. When combining airborne snow depth maps with manual density measurements, corrections may be required to create unbiased maps of snow properties.

Megadunes are fields of huge snow dunes present in Antarctica and other planets, important as they present mass loss on the leeward side (glazed surfaces), in a continent characterised by mass gain. Here, we studied megadunes using remote data and measurements acquired during past field expeditions. For the first time, we quantified their physical properties and demonstrated that they migrate against slope and wind. We further discovered an expansion of glazed surfaces over recent years.

Glacier ice contains information on past climate and can help us understand how the world changes through time. We have found and sampled a buried ice mass in Antarctica that is much older than most ice on Earth and difficult to date. Therefore, we developed a new dating application which showed the ice to be 3 million years old. Our new dating solution will potentially help to date other ancient ice masses, since such old glacial ice could yield data on past environmental conditions on Earth.

The Pamir Alay is located at the edge of regions with anomalous glacier mass changes. Unique long-term in situ data are available for Abramov glacier located in the Pamir Alay. In this study, we use this extraordinary data set in combination with reanalysis data and a coupled surface energy balance–multilayer subsurface model to compute and analyse the distributed climatic mass balance from 1968 to 2020.

Cosmic rays that enter the atmosphere produce secondary particles. These particles react with surface minerals to produce radioactive nuclides. Cosmogenic nuclides are often used to constrain Earth's surface processes. However, the production rates from muons are not well constrained. We measured ¹⁴C in ice with well-constrained exposure history to quantitatively constrain the production rates from muons. We find that the commonly used ¹⁴C production rates are overestimated.

Here we validate soil temperatures from eight reanalysis products across the pan-Arctic, and compare their performance to a newly calculated ensemble mean soil temperature product. We find that most products are biased cold by 2–7 K, especially in the cold season, and that the ensemble mean product outperforms individual reanalysis products. As such, we recommend the product for a wide range of applications – including validation of climate models, or as input to permafrost models.

This paper describes an intercomparison of snow models, of varying complexity, used for numerical weather prediction or academic research. The results show that the simplest models are able, under certain conditions, to reproduce the surface temperature as well as the most complex models. Moreover, the diversity of surface parameters of the models has a strong impact on the temporal variability of the components of the simulated surface energy balance.

In this study, a new permafrost stability mapping is obtained by integrating time-series InSAR and machine learning method, this method provides another alternative for measuring permafrost degradation when the ground temperature is limited to the site-specific measurements. Also, the influences of topography and vegetation coverage on the ground deformations are studied to illustrate that the permafrost stability is high related to the environmental factors.

Snow sublimation is an important component of glacier surface mass balance; however, seldom studied in detail in the Himalayan region owing to data scarcity. We present an 11-year long wintertime snow surface energy balance and sublimation characteristics at the Chhota Shigri Glacier moraine site at 4863 m a.s.l. The estimated winter sublimation is 16–42 % of the winter snowfall at the study site, which signifies how sublimation is important in the Himalayan region.

The Greenland ice-sheet largely depends on the climate state. The uncertainties associated with the year-to-year variability have only a marginal impact on our simulated surface mass budget, this increases our confidence in projections and reconstructions. Basing the simulations based on proxies for, f.ex., temperature, overestimates the surface mass balance, as climatologies lead to small amounts of snowfall every day. This can be reduced by including sub-monthly precipitation variability.

New observations reveal the Thwaites gyre in a habitually ice-covered region in the Amundsen Sea for the first time. This gyre rotates anticlockwise, despite the wind here favours clockwise gyres like the Pine Island Pay gyre – the only other ocean gyre reported in this region. We use an ocean model to suggests that sea ice alters the wind stress felt by the ocean and hence determines the gyre direction and strength. These processes may also be applied to other gyres in polar oceans.

We present a method to compute albedo (percentage of the light reflected) of the cryosphere surface using observations from any optical satellite sensors. This method surpasses all existing models, may be applied globally (Arctic, Antarctic, Sea of Okhotsk) and to any realistic cryosphere surface: sea ice, snow-covered ice, melt-pond, open-ocean, and their mixing. Evaluation of the albedo values calculated using the approach demonstrated excellent agreement with observations.

We present the guidelines developed by the IPA Action Group (within the ESA Permafrost CCI project) to include InSAR-based kinematic information in rock glacier inventories. Nine operators applied these guidelines to eleven regions worldwide; more than 3,600 rock glaciers are classified according to their kinematics. We test and demonstrate the feasibility of applying common rules to produce homogeneous kinematic inventories at global scale, useful for hydrological and climate change purposes.

Sea ice is bright, playing an important role in reflecting incoming solar radiation. The reflectivity of sea ice is affected by the presence of pollutants, such as crude oil, even at low concentrations. Modelling how the brightness of three different types of sea is affected by increasing concentrations of crude oils show that the type of oil, the type of ice, the thickness of the ice, and the size of the oil droplets are important factors. This shows that sea ice is vulnerable to oil pollution.

Sea-ice thickness within the Arctic’s Last Ice Area was measured by sonar during 2009–10. 1.7 million points were measured at 1-m spacing. Half the transect crossed multi-year pack ice, with 3-m mean thickness. After adjustment for seasonal ice growth, the new data were statistically indistinguishable from 1970s data. Ice hazards on a 250-m scale were numerous on the new transect, some extreme (6–14 m thick) but only 400–600 m wide, others thinner (3.5–4.5 m) but 6–14 km across.

In order to overcome internal climate variability, this study investigates spatio-temporal changes of atmospheric drivers within key atmospheric circulation patterns (ACP) over the Greenland Ice Sheet (GrIS). We present the extent of the recent tropospheric warming and increase in water vapor as dependent on season and on the prevailing ACP along with regional impacts of atmospheric drivers on the GrIS surface energy components.

Future ice loss from Antarctica could raise sea levels by several metres, and key to this is the rate at which the ocean melts the ice sheet from below. Existing methods for modelling this process are either too time-consuming or very simplified. We present a new approach, using machine learning to mimic the melt rates calculated by a full ocean model but in a fraction of the time. This could replace to existing methods, providing accurate and efficient melt rate for use in an ice sheet model.

Better understanding of the cryosphere impacts on Arctic marine ecosystems is essential for accurate future projections. We present spatial and temporal trends in freshwater runoff and primary production records since the late 19th century, for a Greenlandic fjord system receiving solid and liquid discharge from the Greenland Ice Sheet. We show that climate warming, freshwater discharge and fjord productivity increased abruptly and concomitantly in the 1990’s, before monitoring efforts begun.

Glacial lakes development around the World has been observed since the end of the Little Ice Age. The whole process is especially rapid in Arctic region what shows last researches. One of the last regions which still has not been covered by data about changes of glacial lakes is the Svalbard Archipelago (Norway). We used remote sensing materials and methods to provide information's about changes of glacial lakes and to show major activity of glacial lakes outburst floods.

Ice crystal alignment in the sheared margins of fast flowing polar ice is important as it may control ice sheet flow rate, from land to the ocean. Sampling shear margins is difficult because of logistical and safety considerations. We show that crystal alignments in a glacier shear margin in Antarctica can be measured using sound waves. Results from a seismic experiment on the 50m scale and from ultrasonic experiments on the decimetre scale match ice crystal measurements from an ice core.

A large area of landfast sea ice exists in the Prydz Bay, and it is always a safety concern to transport cargos on ice to the research stations. Knowing the mechanical properties of sea ice is helpful to solve the issue; however, these data are rarely reported in this region. We explore the effects of sea ice physical properties on the flexural strength, effective modulus, and uniaxial compressive strength, which gives new insights into assessing the bearing capacity of landfast sea ice cover.

Using multi-temporal ArcticDEM and ICESat-2 altimetry data, we document changes in surface elevation of a subglacial lake basin from 2012 to 2021. The long-term measurements show that the subglacial lake was recharged by surface meltwater and a rapid drainage event that occurred in late August 2019 induced an abrupt ice velocity change. Multiple factors regulate the episodic filling and drainage of the lake. Our study also reveals ~64 % of the surface meltwater successfully descended to the bed.

In this study we develop a novel method to map subsurface water flow paths and spatially reference in situ data from such environments. We demonstrate the feasibility of our method with the reconstruction of the flow path of an englacial channel and the water pressures therein. Our method opens up for direct mapping of subsurface water flow paths, not only in glacier hydrology, but also in other applications (e.g. karst caves, pipelines, sewer systems).

The freeze-thaw of the ground is an interesting topic to climatology, hydrology, and other earth sciences. The global freeze-thaw distribution is available by passive microwave remote sensing technique. However, the remote sensing technique indirectly detects freeze-thaw states by measuring the brightness temperature difference between frozen and unfrozen soil. Thus, we present different interprets of the brightness signals to the FT-state by using its sub-daily character.

Representing water at constant density, neglecting cryosuction, and neglecting heat advection are three commonly applied but not validated simplifications in permafrost models to reduce computation complexity at field scale. We investigated this problem numerically by ATS and found that without cryosuction can cause significant bias (10 %~60 %); constant density primarily affects predicting water saturation; ignoring heat advection has the least impact but can improve computation efficiency.

Knowing the type of Antarctic sea ice – first-year ice (grown in one season) or multiyear ice (having survived one summer melt) – is needed in order to understand and model its evolution because the ice types behave and react differently. We have adapted and extended an existing method (originally for the Arctic) and now for the first time can derive daily maps of the Antarctic sea ice type from microwave satellite data. This will allow to build a new data set from 2002 well into the future.

This is the first study to confirm the presence of microplastics in Antarctic snow, highlighting the extent of plastic pollution globally. Fresh snow was collected from Ross Island, Antarctica and subsequent analysis identified an average of 29 microplastic particles per litre of melted snow. The most likely source of these airborne microplastics is local scientific research stations, however modelling shows their origin could have been up to 6000 km away.

This research was conducted to better understand how coupled climate models simulate one of the large-scale interactions between the atmosphere and Arctic sea ice that we see in observational data; the accurate representation of which is important for producing reliable forecasts of Arctic sea ice on seasonal to inter-annual timescales. With network theory, this work shows that models do not reflect this interaction well on average, which is likely due to regional biases in sea ice thickness.

Marine-terminating glaciers have recently retreated dramatically, but the role of anthropogenic forcing remains uncertain. We use idealized model simulations to develop a framework for assessing the probability of rapid retreats in the context of natural climate variability. Our analyses show that century-scale anthropogenic trends can substantially increase the probability of such retreats. This provides a roadmap for future studies to formally attribute recent glacier change to human activity.

This work documents the snowfall variability observed from late XIX century to recent years in Montevergine (Southern Apennines) and discuss its relationship with large-scale atmospheric circulation. The main results lie in the absence of a trend until mid-1970s and in the strong reduction of the snowfall quantity from mid-1970s to 1990s. Montevergine data offer a unique opportunity to investigate meteorological and climatological features of the mountainous environment prior to the 1950s.

On the fringes of polar oceans, sea ice is easily broken by waves. As small pieces of ice, or floes, are more easily melted by the warming waters than a continuous ice cover, it is important to incorporate these floe sizes in climate models. These models simulate climate evolution at the century scale and are built by combining specialised modules. We study the statistical distribution of floe sizes under the impact of waves to better understand how to connect sea ice modules to wave modules.

Four glacial substages exist in Bhutanese Himalaya during LIA. The number of glacial substages has a negative correlation with the glacier length, suggesting the number and occurrence of glacial substages are regulated by the heterogeneous responses of glaciers to climate change. In addition, the analysis of monthly glacier surface mass balance suggests that the decreasing summer temperature dominants the LIA glacier fluctuations in BH.

The coherent backscatter opposition effect can enhance the intensity of radar backscatter from dry snow by up to a factor of two. Despite widespread use of radar backscatter data by snow scientists, this effect has received notably little attention. For the first time, we characterize this effect for the Earth's snow cover with bistatic radar experiments from ground and from space. We are also able to retrieve scattering and absorbing lengths of snow at Ku- and X-band frequencies.

Recent studies have suggested that some portions of the Antarctic Ice Sheet were less extensive than present in the last few thousand years. We discuss how past ice loss and regrowth during this time would leave its mark on geological and glaciological records and suggest ways in which future studies could detect such changes. Determining timing of ice loss and gain around Antarctica and conditions under which they occurred is critical for preparing for future climate warming-induced changes.

Glacier surges are widespread in the Karakoram and have been intensely studied using satellite data and DEMs. In this study, we use time series of such datasets to study three glacier surges in the same region of the Karakoram. We found strongly contrasting advance rates/flow velocities, maximum velocities of 30 m/d and a change of the surge mechanism during a surge. A sensor comparison revealed good agreement, but steep terrain and the two smaller glaciers caused limitations for some of them.

UKESM is the first Earth system model to fully include interactions of the atmosphere and ocean with the Antarctic Ice Sheet. Under low greenhouse-gas scenario, the ice sheet remains stable over the 21st century. Under strong greenhouse-gas scenario, the model predicts strong increases in melting of large ice shelves and strong snow accumulation on the surface. The dominance of accumulation leads to a sea level fall at the end of the century.