Ross A. W. Slater

Synthetic Aperture Radar (SAR) offset tracking is widely used to measure ice velocity on floating ice shelves, however, vertical displacement caused by ocean tides projects into the radar-range direction, introducing apparent horizontal motion unrelated to true ice flow. Here, we develop an observation-driven tide-correction for SAR-derived ice speed measurements using differential range offset tracking (DROT) applied to Sentinel-1 SAR data. The method estimates spatially and temporally varying tidal response coefficients directly from observed radar-range displacement variability and an ocean tide model. Application of the method to SAR-derived ice velocity measurements on Antarctic Ice Shelves shows spatial variability in the magnitude of the tide-induced ice-speed correction, with an Antarctic-wide mean tide-correction range of 106 m/yr, a standard deviation of 71 m/yr and maximum values exceeding 300 m/yr. The largest tide correction range predominantly occurs on freely floating ice shelves in regions of strong tidal forcing, particularly in the Weddell Sea and Antarctic Peninsula. Smaller tide corrections are observed near grounding zones and pinned regions where tidal motion is mechanically constrained. Time-series analyses show that the tide correction systematically reduces non-physical temporal variability in SAR-derived ice velocity products while preserving the large-scale spatial structure of ice flow. Independent validation using GNSS observations on Brunt Ice Shelf shows improved agreement between tide-corrected satellite-based ice speed and in situ measurements. Our results demonstrate that tide-induced apparent motion is a source of variability in SAR-derived ice velocity products on floating ice shelves, highlighting the importance of applying a correction when tide-induced signals are not required.

Marine-terminating glaciers in central and southeast Greenland are major contributors to Greenland’s mass loss making it essential to monitor their changing behaviour. Here, we use over a decade of Sentinel-1 satellite observations to measure the change in ice speed on 66 glaciers between 2014 and 2025. We observe widespread, synchronous acceleration between 2016 and 2020, during which two thirds of glaciers accelerate and 6 more than double their velocity, with many glaciers reaching their fastest speeds since at least 2000. This period is followed by widespread deceleration after 2020, although the slowdown is smaller in magnitude and more gradual, with most glaciers remaining faster than their pre-2016 values. The acceleration coincides with exceptionally warm surface ocean waters in 2016 (+3 °C anomaly), warming at depth in 2018 (+1 °C anomaly) and a prolonged reduction in regional sea-ice concentration, suggesting ocean-driven processes played a role in driving this change. Our results show that ice dynamic change in southeast Greenland has been more spatially extensive and larger magnitude than previously recognised, highlighting the sensitivity of these glaciers to environmental forcing and their susceptibility to rapid, synchronous change.

Synthetic Aperture Radar (SAR) offset tracking is widely used to measure ice velocity on floating ice shelves, however, vertical displacement caused by ocean tides projects into the radar-range direction, introducing apparent horizontal motion unrelated to true ice flow. Here, we develop an observation-driven tide-correction for SAR-derived ice speed measurements using differential range offset tracking (DROT) applied to Sentinel-1 SAR data. The method estimates spatially and temporally varying tidal response coefficients directly from observed radar-range displacement variability and an ocean tide model. Application of the method to SAR-derived ice velocity measurements on Antarctic Ice Shelves shows spatial variability in the magnitude of the tide-induced ice-speed correction, with an Antarctic-wide mean tide-correction range of 106 m/yr, a standard deviation of 71 m/yr and maximum values exceeding 300 m/yr. The largest tide correction range predominantly occurs on freely floating ice shelves in regions of strong tidal forcing, particularly in the Weddell Sea and Antarctic Peninsula. Smaller tide corrections are observed near grounding zones and pinned regions where tidal motion is mechanically constrained. Time-series analyses show that the tide correction systematically reduces non-physical temporal variability in SAR-derived ice velocity products while preserving the large-scale spatial structure of ice flow. Independent validation using GNSS observations on Brunt Ice Shelf shows improved agreement between tide-corrected satellite-based ice speed and in situ measurements. Our results demonstrate that tide-induced apparent motion is a source of variability in SAR-derived ice velocity products on floating ice shelves, highlighting the importance of applying a correction when tide-induced signals are not required.

Synthetic Aperture Radar (SAR) offset tracking is widely used to measure ice velocity on floating ice shelves, however, vertical displacement caused by ocean tides projects into the radar-range direction, introducing apparent horizontal motion unrelated to true ice flow. Here, we develop an observation-driven tide-correction for SAR-derived ice speed measurements using differential range offset tracking (DROT) applied to Sentinel-1 SAR data. The method estimates spatially and temporally varying tidal response coefficients directly from observed radar-range displacement variability and an ocean tide model. Application of the method to SAR-derived ice velocity measurements on Antarctic Ice Shelves shows spatial variability in the magnitude of the tide-induced ice-speed correction, with an Antarctic-wide mean tide-correction range of 106 m/yr, a standard deviation of 71 m/yr and maximum values exceeding 300 m/yr. The largest tide correction range predominantly occurs on freely floating ice shelves in regions of strong tidal forcing, particularly in the Weddell Sea and Antarctic Peninsula. Smaller tide corrections are observed near grounding zones and pinned regions where tidal motion is mechanically constrained. Time-series analyses show that the tide correction systematically reduces non-physical temporal variability in SAR-derived ice velocity products while preserving the large-scale spatial structure of ice flow. Independent validation using GNSS observations on Brunt Ice Shelf shows improved agreement between tide-corrected satellite-based ice speed and in situ measurements. Our results demonstrate that tide-induced apparent motion is a source of variability in SAR-derived ice velocity products on floating ice shelves, highlighting the importance of applying a correction when tide-induced signals are not required.

As the climate continuous to warm, glaciers on the Antarctic Peninsula (AP) are experiencing rapid dynamic changes, including accelerated rates of thinning, terminus retreat, and ice flow, all of which have significant implications for global sea level rise and climate feedback mechanisms. These glaciological changes unfold over varying timescales spanning from months to decades, necessitating temporally and spatially detailed monitoring. Here, we used sub-seasonal records of terminus area change (2013–2023) together with high-resolution satellite-derived ice surface velocity measurements (2014–2024) to investigate the evolution of 42 key outlet glaciers on the northern AP. We found that during the past decade, these glaciers underwent substantial but spatially heterogeneous changes in terminus position and ice flow velocity. Cumulative ice loss amounted to ~279 km², with 73 % of this loss occurring on the eastern side, particularly within the Larsen B embayment. By contrast, western glaciers showed smaller, more variable responses. Overall, 71 % of glaciers accelerated, though most eastern glaciers displayed slight trends of slowdown – except in the Larsen B region, where major calving events beginning in early 2022 were followed by drastic increases in velocity, with some glaciers more than doubling their flow speed. In addition, a seasonality analysis revealed widespread inter-annual variability: two-thirds of glaciers showed strong to very strong seasonal fluctuations in flow speed, and about half exhibited comparable signals in terminus change. Cross-correlation analysis further indicated that, for most glaciers, terminus area changes and ice velocity dynamics had only minimal influence on one another. These results highlight the spatially and temporally heterogeneous nature of glacier dynamics on the northern AP, suggesting that glacier change in this region is shaped by a combination of environmental drivers and glacier-specific factors operating on widely varying timescales. They underscore the need for detailed, high-resolution observations and continuous monitoring to improve the understanding of glacier evolution under ongoing climatic and environmental change.

As the climate continuous to warm, glaciers on the Antarctic Peninsula (AP) are experiencing rapid dynamic changes, including accelerated rates of thinning, terminus retreat, and ice flow, all of which have significant implications for global sea level rise and climate feedback mechanisms. These glaciological changes unfold over varying timescales spanning from months to decades, necessitating temporally and spatially detailed monitoring. Here, we used sub-seasonal records of terminus area change (2013–2023) together with high-resolution satellite-derived ice surface velocity measurements (2014–2024) to investigate the evolution of 42 key outlet glaciers on the northern AP. We found that during the past decade, these glaciers underwent substantial but spatially heterogeneous changes in terminus position and ice flow velocity. Cumulative ice loss amounted to ~279 km², with 73 % of this loss occurring on the eastern side, particularly within the Larsen B embayment. By contrast, western glaciers showed smaller, more variable responses. Overall, 71 % of glaciers accelerated, though most eastern glaciers displayed slight trends of slowdown – except in the Larsen B region, where major calving events beginning in early 2022 were followed by drastic increases in velocity, with some glaciers more than doubling their flow speed. In addition, a seasonality analysis revealed widespread inter-annual variability: two-thirds of glaciers showed strong to very strong seasonal fluctuations in flow speed, and about half exhibited comparable signals in terminus change. Cross-correlation analysis further indicated that, for most glaciers, terminus area changes and ice velocity dynamics had only minimal influence on one another. These results highlight the spatially and temporally heterogeneous nature of glacier dynamics on the northern AP, suggesting that glacier change in this region is shaped by a combination of environmental drivers and glacier-specific factors operating on widely varying timescales. They underscore the need for detailed, high-resolution observations and continuous monitoring to improve the understanding of glacier evolution under ongoing climatic and environmental change.

The Greenland Ice Sheet is a major contributor to global sea-level rise, with its mass loss raising global sea-levels by 13.59 ± 1.27 mm from 1992 to 2020. Changes to the ice dynamics of the Greenland Ice Sheet make up a significant part of this mass loss, meaning that monitoring and understanding changes in ice dynamics is crucial to assessing contemporary sea-level rise and making projections of its future.Since 2014, the European Space Agency’s Sentinel-1 synthetic aperture radar constellation has provided near-continuous, weather-independent coverage of the Greenland Ice Sheet, with 6–12 day repeat intervals over almost all outlet glaciers. We process the full Sentinel-1 archive using an intensity feature offset tracking workflow implemented in GAMMA Remote Sensing to produce a dense, decade-spanning time series of ice velocity at 100 m resolution. This Sentinel-1 derived ice velocity dataset is extremely valuable, capturing long-term speed trends and short-term interannual variability due to seasonal drivers. However, analysing this 60 TB dataset efficiently and obtaining maximum scientific value from it is a substantial data engineering challenge, as the data volume greatly exceeds available memory quotas on HPC systems, even for relatively small geographic areas.Here, we address this challenge with an analysis pipeline built on the Xarray, Dask, and Zarr python packages, and deployed on a HPC service. This pipeline allows both large scale interactive analysis in Jupyter notebooks, streaming to GIS software, and traditional batch processing. We leverage these tools we calculate ice-sheet wide speed change, seasonal speed variability and ice discharge in a fast, reproducible and scalable manner.Our results reveal a highly heterogeneous dynamic response across Greenland, with neighbouring glaciers often exhibiting contrasting behaviour over the past decade. We find that short-term and seasonal variability dominates the velocity signal for most glaciers, often exceeding long-term speed changes. These findings highlight the importance of resolving short-term ice-dynamic processes when assessing Greenland’s contribution to future sea-level rise and the benefit of efficient big-data processing workflows.

The Antarctic Peninsula is among the most rapidly warming regions on Earth and has experienced widespread glacier retreat and acceleration since at least the 1980s, with significant implications for global sea level rise. Glacier change in this region unfolds across a wide range of timescales, spanning from short-lived dynamic events that can trigger persistent adjustments to recurring seasonal variability. However, Earth observation datasets that capture glaciological variables such as ice velocity or calving front dynamics at intra-annual timescales remain scarce. This is largely due to the small size and fast ice flow of Antarctic Peninsula glaciers, combined with complex topography, variable climate, and extreme weather conditions.Here, we address this observational gap by leveraging a newly developed dataset of sub-seasonal terminus area change records (2013–2023) together with high-resolution satellite-derived ice surface velocity measurements (2014– 2024) to investigate the dynamics of 42 key outlet glaciers on the northern Antarctic Peninsula.Our results reveal widespread glacier retreat and acceleration, with cumulative ice loss amounting to ~279 km². The majority of this loss (73 %) was observed for glaciers on the eastern Antarctic Peninsula, particularly within the Larsen B embayment, and is attributed to major calving events in early 2022. Although 71 % of the glaciers accelerated over the study period, most eastern glaciers displayed slight trends of slowdown – except for those in the Larsen B embayment, where initial deceleration was followed by abrupt and pronounced velocity increases after the calving events, with some glaciers more than doubling their flow speed. Seasonal analysis further indicates substantial inter-annual variability, with two-thirds of glaciers exhibiting strong seasonal velocity fluctuations, and around half displaying comparable signals in terminus area change.Overall, the findings demonstrate the persistence of long-term trends of glacier retreat and flow acceleration, while also highlighting substantial spatial and temporal heterogeneity in glacier dynamics across the region, underscoring the need for temporally and spatially detailed monitoring.