Additional portals for meteorology data

As discussed in the previous chapter, the GEOS-Chem Input Data portal is the main source of input data for GEOS-Chem Classic, GCHP, and the HEMCO standalone model. This portal contains the entire catalog of emissions inventories, chemical inputs, initial conditions, and most years of GEOS-FP, MERRA-2, and GEOS-IT meteorology.

We also maintain two additional data portals for special data sets.

GEOS-Chem Nested Input Data

The GEOS-Chem Nested Input data portal (aka s3://gcgrid) stores GEOS-FP and MERRA-2 meteorology fields that have been cropped to specific nested-grid domains. These data can be used to perform high-resolution inversions with the Integrated Methane Inversion (IMI) workflow.

Data stored at the GEOS-Chem Nested Input Data portal is covered by the AWS Open Data Sponsorship Program. and may be downloaded without incurring any data egress fees.

Available nested-grid meteorology (2018 to present day)

Nested domain	Meteorology	Grid
Africa	GEOS-FP	0.125° x 0.15625° AF nested grid [1]
Africa	GEOS-FP	0.25° x 0.3125° AF nested grid
Asia	GEOS-FP	0.125° x 0.15625° AS nested grid [2]
Asia	GEOS-FP	0.25° x 0.3125° AS nested grid
Asia	MERRA-2	0.5° x 0625° AS nested grid
Europe	GEOS-FP	0.25° x 0.3125° EU nested grid
Europe	MERRA-2	0.5° x 0625° EU nested grid
Middle East	GEOS-FP	0.25° x 0.3125° ME nested grid
North America	GEOS-FP	0.125° x 0.15625° NA nested grid [3]
North America	GEOS-FP	0.25° x 0.3125° NA nested grid
North America	MERRA-2	0.5° x 0625° NA nested grid
Oceania	GEOS-FP	0.25° x 0.3125° OC nested grid
Russia	GEOS-FP	0.25° x 0.3125° RU nested grid
South America	GEOS-FP	0.125° x 0.15625° SA nested grid [4]
South America	GEOS-FP	0.25° x 0.3125° SA nested grid

Notes

[1]

Winds, pressures, and specific humidity are read at 0.125° x 0.15625° over the nested Africa domain. Other met fields are taken from the GEOS-FP 0.25° x 0.3125° AF nested grid archive.

[2]

Winds, pressures, and specific humidity are read at 0.125° x 0.15625° over the nested Asia domain. Other met fields are taken from the GEOS-FP 0.25° x 0.3125° AS nested grid archive.

[3]

Winds, pressures, and specific humidity are read at 0.125° x 0.15625° over the nested North America domain. Other met fields are taken from the GEOS-FP 0.25° x 0.3125° NA nested grid archive.

[4]

Winds, pressures, and specific humidity are read at 0.125° x 0.15625° over the nested South America domain. Other met fields are taken from the GEOS-FP 0.25° x 0.3125° SA nested grid archive.

The data can be accessed by:

• AWS S3 Explorer (https://gcgrid.s3.amazonaws.com/index.html)

• Direct HTTP or wget download

• GEOS-Chem Classic dry-run simulation

Cropping global meteorology to other domains

If the region that you wish to simulate is not one of the pre-cut nested domains listed above, or you don’t find the years you need, you may crop the global meteorology archive to a domain and a year range of your own choosing. This is a one-time preprocessing step; once the cropped files exist, GEOS-Chem reads them exactly as it would read the pre-cut nested-grid data.

Note

Reading global meteorology directly into a nested-grid simulation also works, but is much slower and is not recommended.

Sample scripts for cropping the global meteorology archives are included at this portal, in the folders listed below.

Meteorology	Folder containing the cropping scripts
GEOS-FP (0.25° x 0.3125°)	GEOS_0.25x0.3125/crop_met_fields (README, crop_met.sh)
MERRA-2 (0.5° x 0.625°)	GEOS_0.5x0.625/MERRA2/crop_met_fields (README, crop_met.sh)

Each folder contains a crop_met.sh script, which downloads the global meteorology for a given month and crops it to a user-specified longitude/latitude box with the Climate Data Operators (CDO); a nc_chunk.pl script, which chunks and compresses the cropped files with the netCDF Operators (NCO); and a README with instructions for editing the user settings in crop_met.sh.

GCAP 2.0 meteorology hosted at U. Rochester

The atmos.earth.rochester.edu portal (curated by Lee Murray at the University of Rochester) contains the GCAP 2.0 meteorological data inputs for use with GEOS-Chem simulations.

The data can be accessed by:

• Direct HTTP or wget download (http://atmos.earth.rochester.edu/input/gc/ExtData/)

• GEOS-Chem Classic dry-run simulation