SMB: surface mass balance and surface climate
Surface mass balance and surface climate of the ice sheets from regional climate models, remapped onto the grids of the domains. SMB is a thematic dataset made by remapping (see Gridded data): its products are defined in SMB/remap.toml.
Products
| Product | Source | Fields | Domains |
|---|---|---|---|
SMB-RACMO2.4p1-1981-2010, SMB-RACMO2.4p1-1991-2020, SMB-RACMO2.4p1-annual; annual means SMB-RACMO2.4p1-1981-2010-annual-mean, SMB-RACMO2.4p1-1991-2020-annual-mean |
van Dalum et al. (2025): RACMO2.4p1 forced by ERA5, 11 km, doi:10.5194/tc-19-4061-2025, data doi:10.5281/zenodo.19255213 | smb, pr, sf, runoff, melt, subl (kg m-2 yr-1), t2m, T_srf (K): monthly climatologies and their annual means, annual values 1979-2023; z_srf, f_ice, mask_land, mask_icesheet |
Antarctica |
SMB-RACMO2.3p2-1981-2010, SMB-RACMO2.3p2-1991-2020, SMB-RACMO2.3p2-1985-2014, SMB-RACMO2.3p2-annual; annual means SMB-RACMO2.3p2-1981-2010-annual-mean, SMB-RACMO2.3p2-1991-2020-annual-mean, SMB-RACMO2.3p2-1985-2014-annual-mean |
van Wessem et al. (2018, 2023): RACMO2.3p2 forced by ERA5, 27 km, doi:10.5194/tc-12-1479-2018, data doi:10.5281/zenodo.7760491 | smb, pr, sf, runoff, melt, subl (kg m-2 yr-1), t2m, T_srf (K): monthly climatologies and their annual means, annual values 1979-2022; z_srf, f_ice, mask_grounded. 1985-2014: reference climate of ISMIP7, filled over the whole grid (see below) |
Antarctica |
SMB-MARv3.14-1961-1990, SMB-MARv3.14-1981-2010, SMB-MARv3.14-1991-2020, SMB-MARv3.14-annual; annual means SMB-MARv3.14-1961-1990-annual-mean, SMB-MARv3.14-1981-2010-annual-mean, SMB-MARv3.14-1991-2020-annual-mean |
Fettweis et al. (2017), Timmermans et al. (2026): MAR v3.14.3 forced by ERA5, 1 km, doi:10.5194/tc-11-1015-2017 | smb, pr, sf, rf, melt, runoff (kg m-2 yr-1), t2m, T_srf (K): monthly climatologies and their annual means, annual values 1940-2025; z_srf, f_ice, mask |
Greenland |
All sources use the same names and units: fluxes in kg m-2 yr-1 (mm water equivalent per year), also for the months of a climatology, and temperatures in K. The -annual-mean products are the annual means (x, y) of the monthly climatologies, the months weighted by their mean length over the period. Each file also has f_valid, the fraction of each cell covered by the source. Fields are remapped conservatively and smoothed on grids finer than the source; the masks are remapped as classes.
SMB-RACMO2.3p2-1985-2014 (and its annual mean) is a reference climate for model forcing (the reference period of the ISMIP7 experiments), defined on the whole grid: smb is pr + subl off the glaciated surfaces (see vanWessem2023_racmo23), and smb, pr, sf, t2m, T_srf and z_srf are filled outside the RACMO domain (the corners of the grids) by harmonic interpolation (fill, mask = "all", marked by mask_fill).
SMB-RACMO2.3p2-1981-2010, SMB-MARv3.14-1961-1990 and SMB-MARv3.14-1981-2010 (and their annual means) are also defined on the whole grid, for model forcing, but filled where there are no source data (f_valid = 0, marked by mask_fill_<field>) as follows:
smbis defined on the ice only (RACMO: f_ice >= 0.1; MAR: its ice mask, see Fettweis2017_mar314, so that the cells at the ice margin are not mixed with the strongly negative values of MAR off the ice). Off the ice and outside the RCM domain (e.g. the ice caps of the Canadian Arctic on the GRL grids), it is the linear regression ofsmbon the surface elevation over the cells with data within 150 km (grown until there are 20), at the elevation of the cell (max(z_srf, 0)ofTOPO-BedMachine-v4) clamped to the range of the elevations of these cells (no extrapolation), at most -91.7 kg m-2 yr-1 (-0.1 m yr-1 ice equivalent, with 917 kg m-3): a small negative surface mass balance off the ice, on land and ocean. In the monthly climatologies the bound applies to the annual mean (months weighted by their length), all months shifted by the same amount (fill,method = "elevation_regression", see Gap filling).t2mandT_srf: the same regression on the elevation (a local lapse rate), without bound. They are missing only outside the RCM domain (RACMO: the corners of the grids; MAR: e.g. the Canadian Arctic), as the RCMs give them on land and ocean.z_srf(the RCM orography): the elevation of the regression,max(z_srf, 0)ofTOPO-BedMachine-v4, in every cell wheresmbis filled (method = "elevation",gaps_of = "smb"), also where the RCM has an orography of its own (e.g. 0 over the ocean of MAR, in the Canadian Arctic), so that it is the reference elevation of the filledsmb(e.g. for an elevation correction in a model). Elsewhere it is the RCM orography, the elevation of the RCMt2mandT_srfwhere onlysmbis filled.pr,sf(andrffor MAR, so thatpr = sf + rfholds): harmonic interpolation. Off the ice,smbis notprminus runoff or sublimation (which stay missing there), but the bound above.
runoff, melt and subl are not filled.
Precision
The float fields are rounded on output to a tolerance by kind (see Precision and file sizes): smb, pr, sf, rf, runoff, melt and subl to 1%; t2m and T_srf to 0.01 K; z_srf to 0.01 m; f_ice and f_valid to 0.001. The masks are exact.
Licences
| Source | Licence |
|---|---|
| van Dalum et al. (2025), RACMO2.4p1 | CC BY 4.0 |
| van Wessem et al. (2023), RACMO2.3p2 | CC BY 4.0 |
| Fettweis et al. (2017), MAR v3.14 | No licence stated (freely available at ftp.climato.be, cite the references); publishing assumed to be allowed |
Making the dataset
julia -t 8 fesmdata.jl remap SMBDownloads
Download the files with fesmdata.jl into $FESMDATA_PRODUCTS/<Domain>/<GRID>/ (see Download), or one by one from the links below. All released datasets are listed under Products.
Antarctica
Version 2.5.1 (2026-10-16, packages). 48 files, 1.26 GB.
julia fesmdata.jl fetch SMB Antarctica # all grids julia fesmdata.jl fetch SMB ANT-32KM # one grid
ANT-4KM 12 files, 839.1 MB
ANT-8KM 12 files, 291.9 MB
ANT-16KM 12 files, 96.9 MB
ANT-32KM 12 files, 30.7 MB
Greenland
Version 2.5.1 (2026-10-16, packages). 39 files, 787.9 MB.
julia fesmdata.jl fetch SMB Greenland # all grids julia fesmdata.jl fetch SMB GRL-32KM # one grid
GRL-1KM 6 files, 509.3 MB
GRL-2KM 6 files, 165.0 MB
GRL-4KM 6 files, 52.0 MB
GRL-8KM 7 files, 43.3 MB
GRL-16KM 7 files, 13.7 MB
GRL-32KM 7 files, 4.5 MB
Nests and crops
These nests and crops get products of SMB by cropping those of the domain (or crop) that contains them: fetch downloads these and cuts them (see Nests and crops), e.g. julia fesmdata.jl fetch SMB Amery.
| Nest or crop | Cut from | Products |
|---|---|---|
| Amery | Antarctica | 12 |
| Amundsen | Antarctica | 12 |
| FilchnerRonne | Antarctica | 12 |
| Helheim | Greenland | 7 |
| Jakobshavn | Greenland | 7 |
| NEGIS | Greenland | 7 |
| Petermann | Greenland | 7 |
| PineIsland | Antarctica | 12 |
| Ross | Antarctica | 12 |
| Thwaites | Antarctica | 12 |
| WilkesBasin | Antarctica | 12 |
Figures
MARv3.14-1961-1990
MARv3.14-1981-2010
MARv3.14-1991-2020
MARv3.14-annual
RACMO2.3p2-1981-2010
RACMO2.3p2-1985-2014
RACMO2.3p2-1991-2020
RACMO2.3p2-annual
RACMO2.4p1-1981-2010
RACMO2.4p1-1991-2020
RACMO2.4p1-annual
