Building a unified elevation data analysis tool in the frame of the CO3D mission

Satellites can measure how fast glaciers move, which helps scientists understand ice loss and rising sea levels. However, these measurements have rarely been checked against ground-based observations on small mountain glaciers. We compared satellite-derived glacier speeds against precise ground measurements. The satellite data generally agreed well with ground observations. Our results help scientists use satellite glacier velocity data more reliably.

The Antarctic Peninsula is a mountainous region containing an ice sheet and peripheral glaciers. Differences remain between the methods used to estimate its mass changes. We use thousands of digital elevation models derived from high resolution stereoscopic images to calculate a new estimate of mass changes. We find that between 2007 and 2021, the ice sheet lost -28±6Gt/a and its peripheral glaciers -14±3Gt/a. We highlight the importance of resolving fine-scale changes in complex coastal areas.

Avalanches are vital for glacier survival, yet their impact is difficult to quantify. We used low-cost cameras and drones to monitor an avalanche cone in the French Alps for two years. By accounting for ice flow, we found that avalanches can deposit 30 meters of snow annually – 50 times more than normal snowfall. This high-frequency data reveals that these cones fill until reaching a specific steepness, after which new snow slides further down to the base.

Sub-annual glacier surface velocity derived from remote sensing images are receiving increasing attention. In the meantime, systematic seasonal errors (i.e. biases) have been reported in time series derived from optical images on various landforms, such as landslides or dunes. The extent to which such biases affect glacier velocity maps remains poorly investigated. Here, we propose characterizing the amplitude and spatial distribution of these seasonal biases.

We reconstruct historical topography for a rapidly warming Antarctic region with limited existing data. Using approximately 2000 aerial photographs from the year 1989 over the western Antarctic Peninsula and nearby islands, we created detailed elevation models and orthoimages that have high accuracy compared to recent satellite data. This open dataset aids tracking historical ice loss and its role in sea level rise.

This study introduces a new workflow to process the elevation time series of glacier surges, an ice flow instability. Applied to a dense, 20-year satellite dataset of glacier surface elevation, the method filters and interpolates these changes on a monthly scale, revealing detailed patterns and estimates of mass transport. The dataset produced by this method allows for a more accurate and a remarkably detailed description of glacier surges at the scale of a large region.

While global annual glacier velocities are openly accessible, sub-annual velocity time series are still lacking. This hinders our ability to understand flow processes and the integration of these observations in numerical models. We introduce an open source Python package called TICOI (Temporal Inversion using linear Combinations of Observations, and Interpolation) to fuse multi-temporal and multi-sensor image-pair velocities produced by different processing chains to produce standardized sub-annual velocity products.

The NASA MEaSUREs Inter-mission Time Series of Land Ice Velocity and Elevation (ITS_LIVE) project provides glacier and ice sheet velocity products for the full Landsat, Sentinel-1, and Sentinel-2 satellite archives and will soon include data from the NISAR satellite. This paper describes the ITS_LIVE processing chain and gives guidance for working with the cloud-optimized glacier and ice sheet velocity products.

We reconstruct the evolution of terminus position, ice thickness, and surface flow velocity of the reference Abramov glacier (Kyrgyzstan) from 1968 to present. We describe a front pulsation in the early 2000s and the multi-annual present-day buildup of a new pulsation. Such dynamic instabilities can challenge the representativity of Abramov as a reference glacier. For our work we used satellite‑based optical remote sensing from multiple platforms, including recently declassified archives.

Avalanches contribute to increasing the accumulation on mountain glaciers by redistributing snow from surrounding mountains slopes. Here we quantified the contribution of avalanches to the mass balance of Argentière Glacier in the French Alps, by combining satellite and field observations to model the glacier dynamics. We show that the contribution of avalanches locally increases the accumulation by 60–70 % and that accounting for this effect results in less ice loss by the end of the century.

Satellites have made it possible to observe glacier elevation changes from all around the world. In the present study, we compared the results produced from two different types of satellite data between different research groups and against validation measurements from aeroplanes. We found a large spread between individual results but showed that the group ensemble can be used to reliably estimate glacier elevation changes and related errors from satellite data.

Avalanches are important for the mass balance of mountain glaciers, but few data exist on where and when they occur and which glaciers they affect the most. We developed an approach to map avalanches over large glaciated areas and long periods of time using satellite radar data. The application of this method to various regions in the Alps and High Mountain Asia reveals the variability of avalanches on these glaciers and provides key data to better represent these processes in glacier models.

The South Col Glacier is a small body of ice and snow located on the southern ridge of Mt. Everest. A recent study proposed that South Col Glacier is rapidly losing mass. In this study, we examined the glacier thickness change for the period 1984–2017 and found no thickness change. To reconcile these results, we investigate wind erosion and surface energy and mass balance and find that melt is unlikely a dominant process, contrary to previous findings.

We established a new inventory of surging glaciers across High Mountain Asia based on glacier elevation changes and morphological changes during 1970s–2020. A total of 890 surging and 336 probably or possibly surging glaciers were identified. Compared to the most recent inventory, this one incorporates 253 previously unidentified surging glaciers. Our results demonstrate a more widespread surge behavior in HMA and find that surging glaciers are prone to have steeper slopes than non-surging ones.

How glaciers have responded to climate change over the last 20 years is well-known, but earlier data are much more scarce. We change this in Switzerland by using 22 000 photographs taken from mountain tops between the world wars and find a halving of Swiss glacier volume since 1931. This was done through new automated processing techniques that we created. The data are interesting for more than just glaciers, such as mapping forest changes, landslides, and human impacts on the terrain.

We present a new approach for modelling debris area and thickness evolution. We implement the module into a combined mass-balance ice-flow model, and we apply it using different climate scenarios to project the future evolution of all glaciers in High Mountain Asia. We show that glacier geometry, volume, and flow velocity evolve differently when modelling explicitly debris cover compared to glacier evolution without the debris-cover module, demonstrating the importance of accounting for debris.