DOI: 10.6096/1007
title: Ice velocity and thickness of the world's glaciers

description: ###Global mapping of surface ice flow velocity and ice thickness of glaciers around the world from Millan et al. (2022)

The dataset presented here contains a global mapping of surface ice flow velocity and the ice thickness of glaciers around the world. Glacier surface flow velocities were calculated using *Sentinel-2/ESA*, *Landsat-8/USGS*, *Venμs/CNES-ISA*, *Pléiades/AirbusD&S* and radar data from *Sentinel-1/ESA*. 

*Reference and link to RGI*: The Randolph Glacier Inventory (RGI) is used to define the glacier outlines. This inventory provides global glacier outlines compiled from maps, aerial photographs and satellite images and can be found [here](https://www.glims.org/RGI/rgi60_dl.html).

*Projections* : UTM (EPSG:326XX for the northern hemisphere and EPSG:327XX for the southern hemisphere) and Polar Stereographic (EPSG:3031 for Antarctica and EPSG:3414 for Greenland)

Data are posted at 50 m horizontal spacing. 

Data are provided as geotiff `.tif` that can be opened in geographic information system. The naming convention is `VAR_RGI-X.Y_date.tif`, where:
- `VAR` is the type of variable contained in the geotiff, 
- `RGI-X.Y` indicates the RGI region number with `X` (1 to 19) and sub-region with `Y`, and 
- `date` gives the date of the file generation. 

###Ice velocity product

Optical satellite images from [Landsat-8](https://www.usgs.gov/landsat-missions/landsat-8), [Sentinel-2](https://sentinel.esa.int/web/sentinel/missions/sentinel-2), [Venμs](https://venus.cnes.fr/fr) and synthetic aperture radar images from [Sentinel-1](https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-1) were used globally to map glacier surface flow velocity in 2017 and 2018. 

5 different variables (`VAR`) are provided to describe :
- `V` the magnitude of the ice velocity in m/year,
- `VX` the component of velocity in m/year in x direction (east-west; positive toward east),
- `VY` the component of velocity in m/year in y direction (north-sourth; positive toward north),
- `STDX` the standard deviation of `VX` individual measurements in m/year, and 
- `STDY` the standard deviation of `VY` individual measurements in m/year.

No data values are set to NaN and zero for all layers.

Note : the ice velocity of the ice sheets are not provided here. The ice velocity map of Antarctica can be found here https://nsidc.org/data/NSIDC-0754/versions/1 , and the ice velocity map of Greenland can be found here https://nsidc.org/data/NSIDC-0646/versions/1

###Ice thickness product

Data are posted at 50 m horizontal spacing in georeferenced geotiff  format `.tiff`.

2 different variables (`VAR`) are provided to describe :
- `THICKNESS` the ice thickness model in m,
- `ERRTHICKNESS` the estimated error on the ice thickness model in m

Note : the ice thickness of glaciers connected to the coast or ice shelves of the Antarctic ice sheet are not provided here. Thickness map for these areas can be found here https://nsidc.org/data/NSIDC-0756/versions/1 

Surface reference used : access the Arctic DEM at https://www.pgc.umn.edu/data/arcticdem/ ; the ASTER GDEM v3 is available at https://search.earthdata.nasa.gov and the TanDEM-X global DEM at https://geoservice.dlr.de