new INSTRUCTIONS.md

INSTRUCTIONS.md

@@ -24,7 +24,7 @@ Before processing and combining all input layers to the basemap, we need to down
 #### General Bathymetric Chart of the Oceans (GEBCO)
 GEBCO is the DEM basis for the basemap. Download GEBCO in its global netCDF version to avoid the GeoTIFF tiles. Details on the GEBCO dataset can be found [here](https://gitlab.awi.de/sdreutte/basemap/-/blob/master/data/gebco.md).
 Download GEBCO here: https://www.gebco.net/data_and_products/gridded_bathymetry_data/
-The netCDF grid `GEBCO_2020.nc` should be placed in `~/data/gebco/`.
+The netCDF grids `GEBCO_2020.nc` and `GEBCO_2021_sub_ice_topo.nc` should be placed in `~/data/gebco/`.
 
 #### Global Land Ice Measurements from Space (GLIMS)
 To overlay the map with global glaciers, GLIMS stores the necessary data. Download the latest GLIMS dataset as ESRI Shapefile Polygon. Details on the GLIMS dataset can be found [here](https://gitlab.awi.de/sdreutte/basemap/-/blob/master/data/glims.md).