Packages and methods used

In this package, we decided to use GDAL and GRASS software for their functionalities and computational speed. In the same way, we used Cloud Optimized GeoTIFFs (COG) to download only the data needed for all climatic files. This technique can done with the gdal_translate function and the /vsicurl virtual file system. In R itself, terra and stars packages help to handle and visualize Tiff files as R object.

Computing time

Comparison with 3 different areas : New Caledonia, French Guiana and Madagascar.

For all area, resolution is set to 1km. Others parameters don’t change computing time.

Area transform_shp_country_extent get_env_variable get_chelsa_current merge_files get_chelsa_future
Madagascar 2min 13min 25min 6min 1h15min
New Caledonia 2min 5min 9min 8min 47min
French Guiana 2min 3min 6min 2min 25min

Output size

Area layer’s size number of cells
Madagascar 1673 x 875 1.463.875
New Caledonia 689 x 1921 1.323.569
French Guiana 444 x 445 197.580

Type of output

Each output is a multilayer Tiff file with -32768 as NoData value. All values are in Int16 for optimizing space on disk.