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Introduction

New focus group in ISMIP7
Overall aim is to support observational needs for ice sheet modelling, including for:

Initialization – assimilation of ice velocity and surface elevation etc

Deriving new parameterizations – implementation of empirical relationships based on observations

Calibration/Validation – comparisons of modelled and observed parameters, calibration of ensemble members based on observed mass changes

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Lots of progress in observations over the ice sheets

The satellite record covers now more than three decades for ice velocity, elevation changes, & mass changes

1960s imagery over Larsen B glaciers

(North & Barrows, 2024)

ICESat-2 launched in 2018

Crevasses mapping

(Surawy-Stepney et al, 2023)

Grounding line mapping

(Mohajerani et al., 2021)

Calving front mapping

(Baumhoer et al., 2023)

50 years of mass changes derived from EO

New satellites missions enabling finer spatial and temporal resolution for most ice sheet parameters (monthly, a few kms)

Recent work on historical imagery to derive DEMs

Use of AI and deep-learning to make use of the EO archive and process very large datasets

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Action items

Survey ISM groups (July 2024):

Identify priorities and key topics
current datasets used, format of the data, temporal/spatial resolution
11 groups responded

Data tables (June 2025):

List potential datasets to include in collated netcdf file
Choose priority datasets and upcoming products

Curated dataset (Sept 2025):

Thanks to Mathieu!!

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1. Survey results: Current observational datasets used

Topography, Grounding Line & ice mask from BedMachine

Mass changes from IMBIE

Ice velocities from MEaSUREs

Surface elevation changes from laser altimetry (Smith et al., 2020)

+ own 1980s surface DEM

Surface temperature and precipitation from reanalysis or RACMO

Geothermal heat flux maps from various sources

Calving U-NET

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1. Survey results: data needs

Surface elevation and its changes
Geothermal heat flux
Ice temperature, frozen VS thawed bed indicator

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1. Survey results: Spatial/temporal resolution during the contemporary period

Annual is sufficient
High resolution near the grounding line preferred
Between 500 m and 5 km

Would ice sheet wide datasets be useful for singular time stamps or short period?

Not really
For damage, calibrating SMB, melt ponds, ice shelf basal melt

→ Link up with the other FGs

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Data formatting

Various datasets already used
Regular grids preferred, but groups are used to interpolate to their own grids/ISMIP grids
All datasets made available on the same grid would be convenient
Would be helpful to have a recommended set of drainage basins for the ice sheets but can easily be changed in post-processing

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2. Data tables:

https://docs.google.com/spreadsheets/d/1jhr-_g_b7y36BG__zpa5n8YYHl4diMmVEjIGh3G4ivc/edit?usp=sharing

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3. Data files:

Greenland is done
Antarctica is in the works.
Everything is annual, except ice velocity (Greenland)

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Questions for the group:

Upcoming tasks:

Look through data tables. Are we missing any key datasets?
Strategy to integrate with other focus groups on key parameters?

Create Antarctic data file (goal by AGU)
Expand metadata notes for each dataset
Write a paper about data choices and needs

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ISMIP7 observations dataset

for Greenland

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Ice Masks:

Promice Ice mask - 2022

Greene Ice mask - monthly masks from

1972 to 2022

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Drainage basins:

Mouginot basins

Mouginot glacier drainage

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BedMachine mask, bed, and thickness

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Surface elevation

GIMP

GRIMP

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Surface elevation change

Smith dh/dt – dh/dt from laser

altimetry, 2003 to 2019

Khan dh/dt – annual dh/dt from radar and

laser altimetry, 2003 to 2023

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Surface velocity

Velocity mosaic

Velocity time series

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Geothermal heat flux

Colgan et al. (2021)

Martos et al. (2018)

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