Input data set: Land-sea mask

Protocol relation: Protocol
Data Type: Other
Simulation rounds: ISIMIP3b, ISIMIP3a, ISIMIP2b, ISIMIP2a, ISIMIP Fast Track

Land-sea masks, on a global 0.5°x0.5° lat-lon grid, for the different ISIMIP simulation rounds.


Three land-sea masks are offered in ISIMIP3: "landseamask", "landseamask_no-ant" and "landseamask_water-global".

1. "landseamask" is the land-sea mask of the W5E5 dataset. Over all grid cells marked as land by this mask, all climate data that are based on W5E5 (GSWP3-W5E5 as well as climate data bias-adjusted using W5E5) are guaranteed to represent climate conditions over land.
2. "landseamask_no-ant" is the same as the previous one but without Antarctica.
3. "landseamask_water-global" is the same as the generic land-sea mask from ISIMIP2b, to be used for global water simulations in ISIMIP3.

There is one generic land-sea mask from ISIMIP2b. This one marks more grid cells as land than "landseamask" for ISIMIP3. Over those additional land cells, the climate data that are based on W5E5 (GSWP3-W5E5 as well as climate data bias-adjusted using W5E5) are not guaranteed to represent climate conditions over land. Instead they may represent climate conditions over sea or a mix of conditions over land and sea.

** Note: For models that have grid cells partially covered by land and ocean, modelers should indicate the LSM used within the model documentation and provide their land-sea mask along the data uploads.


The land-sea mask used to create the ISIMIP2b land-only climate input-data files differs from the intended CRU land-sea mask (the land-sea mask of the WATCH forcing data that were used for bias correction in the ISIMIP fast track). The difference pertains to one grid cell only: Antipodes Islands located at 49.75°S, 178.75°W in the CRU land-sea mask and at 49.25°S, 178.75°E in the ISIMIP2b land-sea mask. This mismatch should be irrelavant for most analyses and modelling groups. If necessary, climate input data for the real Chatham Island grid cell can be retrieved from the un-masked climate input data files.

Download Instructions

For ISIMIP participants, these files are available for download on the DKRZ server. For ISIMIP2b, using the path ISIMIP2b: /ISIMIP/ISIMIP2b/InputData/landseamask/. For ISIMIP3a (equivalent for ISIMIP3b), using the path /ISIMIP/ISIMIP3a/InputData/geo_conditions/landseamask/.

For external users, these data will be made available on the ISIMIP ESGF server ( Currently they are available via an rsync facility (described here:, for which the password will be provided upon request (