DOI: 10.5281/zenodo.16338734
title: A nine-year record of slush on the Greenland Ice Sheet

description: A Nine-Year Record of Slush Extent on the Greenland Ice Sheet (2016–2024)

Emily Glen, Lancaster University

Dataset Description

This dataset provides the first near-decadal, ice-sheet-wide record of slush extent on the Greenland Ice Sheet, covering melt seasons from 2016 to 2024. Slush is defined as partially saturated snow or firn, formed by meltwater accumulation and refreezing, with significant implications for runoff, energy balance, and supraglacial drainage evolution.

Methodology





Satellite source: Sentinel-2 MSI




Classification: Supervised Random Forest model in Google Earth Engine




Output: Monthly classifications at 10 m resolution




Regional summaries produced for six basins (SW, CW, NW, NO, NE, SE)



Contents





Monthly slush shapefiles (2016–2024)Classified monthly slush extent (May–September) for each year.




Annual compositesUnion of monthly slush extent per year (2016–2024).



Format and Metadata





File format: ESRI Shapefile (.shp, .shx, .dbf, .prj)




Coordinate system: EPSG:3413 — WGS 84 / NSIDC Sea Ice Polar Stereographic North



Usage Notes





Cloud-covered regions are excluded from classification.




Slush extent may be underestimated in persistently cloudy areas.




Use in conjunction with climate data (e.g., RACMO) for full context.



Funding

This work was conducted under the 4DGreenland project, funded by the European Space Agency (ESA) and the UK Engineering and Physical Sciences Research Council (EPSRC).

Dataset DOI

https://doi.org/10.5281/zenodo.16338735

Figures from our Upcoming Paper

Figure 1. Overview map of Greenland separated into six drainage basins: Southwest (SW), Central West (CW), Northwest (NW), North (NO), Northeast (NE), and Southeast (SE) (Mouginot and Rignot, 2019). Red boxes indicate the footprints of the 24 training/validation images used to train and validate the RF classifier.Base map source: Esri.

Figure 2. Flowchart of slush classification workflow adapted from Dell et al. (2022), originally designed for Antarctic ice shelves and modified here for the Greenland Ice Sheet (GrIS).

Figure 3. Slush persistence and average coverage across basins during summer (May–September).





Persistence is indicated by colour (1–9 years).




Circle size represents average slush coverage (2016–2024).




Embedded pie charts show average monthly slush distribution.




Additional overlays:





Ice slab extent (2010–2018; Jullien et al., 2023) – dark green dotted outline




Firn aquifer extent (2010–2014; Miège et al., 2016) – purple dotted outlineBase map source: Esri.





Figure 4. Temporal variability in slush area and climate anomalies (2016–2024).





Top: Total slush area by month (May–September), annually.




Middle: Monthly snowmelt anomalies (mm w.e.) from RACMO (Noël et al., 2019).




Bottom: Monthly near-surface air temperature anomalies (°C) from RACMO.



Figure 5. Bar plots of total slush-covered area (km²) by basin and month.





Each panel shows a specific basin (NW, CW, SW, SE, NE, NO).




Monthly breakdown: May–September.




Overlaid:





Snowmelt anomalies (black lines, mm w.e.)




2 m air temperature anomalies (red lines, °C)




Shaded regions = standard error.