Input data¶

OGGM needs various data files to run. To date, we rely exclusively on open-access data that are all downloaded automatically for the user. This page explains the various ways OGGM uses to get the the data it needs.

At the first import, OGGM will create a cached .oggm directory in your $HOME folder. This directory contains all data obtained from the oggm sample data repository. It contains various files needed only for testing, but also some important files needed for calibration and validation. For example: This directory should be updated automatically when new files are available on GitHub, but if you encounter any problems simply delete it, it will be re-downloaded automatically. All other data: auto-downloads and the ~/.oggm_config file¶ OGGM implements a bunch of logic to make access to the input data as painless as possible, including the automated download of all the required files. Unlike runtime parameters (such as physical constants or working directories), the input data is shared accross runs and even accross computers. Therefore, the paths to previously downloaded data are stored in a simple configuration file that you’ll find in your $HOME folder: the ~/.oggm_config file.

The file should look like:

dl_cache_dir = /path/to/download_cache
tmp_dir = /path/to/tmp_dir
cru_dir = /path/to/cru_dir
rgi_dir = /path/to/rgi_dir
test_dir = /path/to/test_dir
has_internet = True


With:

• dl_cache_dir is a path to a directory where all the files you downloaded will be cached for later use. Most of the users won’t need to explore this folder (it is organized as a list of urls) but you have to make sure to set this path to a folder with sufficient disk space available.
• dl_cache_readonly indicates if writing is allowed in this folder (this is the default). Setting this to True will prevent any further download in this directory (useful for cluster environments, where this data might be available on a readonly folder).
• tmp_dir is a path to OGGM’s temporary directory. Most of the topography files used by OGGM are downloaded and cached in a compressed format. They will be extracted in tmp_dir before use. OGGM will never allow more than 100 .tiff files to exist in this directory by deleting the oldest ones following the rule of the Least Recently Used (LRU) item. Nevertheless, this directory might still grow to quite a large size. Simply delete it if you want to get this space back.
• cru_dir is the location where the CRU climate files are extracted. They are quite large! (approx. 6Gb)
• rgi_dir is the location where the RGI shapefiles are extracted.
• test_dir is the location where OGGM will write some of its output during tests. It can be set to tmp_dir if you want to, but it can also be another directory (for example a fast SSD disk – the data written for testing is much smaller than the input files).

Note

tmp_dir, cru_dir and rgi_dir can be overridden and set to a specific directory by defining an environment variable OGGM_EXTRACT_DIR to a directory path. Similarly the envorinment variables OGGM_DOWNLOAD_CACHE and OGGM_DOWNLOAD_CACHE_RO override the dl_cache_dir and dl_cache_readonly settings.