Using custom regions with the IMI
The IMI supports regions within the following domains:
Africa: 37°S-40°N, 20°W-53°E
Asia: 11°S-55°N, 60°E-150°E
Europe: (33°N-61°N, 30°W-70°E
Middle East: 12°N-44°N, 20°W-70°E
North America: 10°N-70°N, 140°W-40°W
Oceania 50°S-5°N, 110°E-180°E
Russia 41°N-83°N, 19°E-180°E
South America 59°S-16°N, 88°W-31°W
These are the nested-grid windows used in GEOS-Chem for which pre-cut meteorological files are available. You may apply the IMI to other regions, but this requires either using global meteorological fields which can be computationally expensive (not recommended) or cropping global meteorological fields via a pre-processing step.
To facilite cropping global meteorological fields, a sample script (crop_met.sh) has been included with the IMI. This script utilizes the Climate Data Operators (CDO) . It also includes an option to first download global meteorological fields at 0.25° x 0.3125° resolution. The global files are large (approx. 300G per month), so when using that option it is recommend that you process short periods at a time and delete the global files before processing additional periods.
In a text editor, modify the user settings section in crop_met.sh
. The region
defined in crop_met.sh
should be the same or larger than the domain defined for your
IMI in config.yml.
|
Two-letter string to identify region (e.g. |
|
Minimum longitude edge of the region of interest. |
|
Maximum longitude edge of the region of interest. |
|
Minimum latitude edge of the region of interest. |
|
Maximum latitude edge of the region of interest. |
|
Boolean for downloading global 0.25° x 0.3125° meteorology fields for cropping. Default is |
|
Boolean for deleting global meteorology files after cropping. Default is |
|
Directory containing the global high-resolution meteorology fields. |
|
Directory where the cropped meteorology files will be placed. We recommend specifying this as |
The cropped meteorology files can be generated by then executing ./crop_met.sh
at the
command line or submitting the script to your cluster’s scheduler if available. Headers for the
SLURM scheduler are included at the top of the script, but you can modify or remove those as needed.
To utilize the cropped meteorology files in the IMI, you will need to create a new IMI directory. Modify config.yml
so that NestedRegion
matches the value set in crop_met.sh
. This will automatically
add the region ID string in the appropriate locations in the HEMCO_Config.rc
files utilized
by GEOS-Chem.
If you have regional emissions that you would like to use, please see modifying prior emission estimates.
Finally, you can run the IMI preview to quickly check that the IMI is working as expected for your custom region.