For WRF-Chem Users
If you are a WRF-Chem user but you have found this page through search, congratulations! WRF-GC is a model just like WRF-Chem, but uses chemistry provided by the GEOS-Chem chemical model instead of the chemical schemes in WRF. Learn more about WRF-GC.
This page details some differences (such as advantages) of WRF-GC compared to WRF-Chem. It may be useful to existing WRF-Chem users, because the running workflow of WRF-GC is very similar and you can get up and running quickly.
Major differences to WRF-Chem
WRF-GC only supports one chemistry option provided by GEOS-Chem, using
chem_opt = 233. WRF-GC must be downloaded separately, replacing the
WRF. See Downloading WRF-GC.
WRF-GC does not use off-line emissions, instead using on-line emissions computed by HEMCO. You do not need to pre-process any emissions data anymore, and can simply configure emissions using a text file. Most inventories, such as CEDS, MIX, NEI, EDGAR, are available out-of-the-box. MEIC emissions for China, etc. are also developed by other groups. WRF-GC is fully compatible with any emission files used by GEOS-Chem users.
WRF-Chem has X feature, does WRF-GC have it?
Support for WRF physical/dynamics options… Maybe. But this is also a maybe in WRF-Chem. See Domain, meteorology, and configuration for a table with supported options.
Nested domains? Yes.
Aerosol-radiation and aerosol-cloud interactions? Yes, using GEOS-Chem aerosols. Feng et al., 2021 GMD describes this capability.
Nudging? Yes. See Nudging meteorology.
Initial/boundary conditions? Yes, from GEOS-Chem global outputs. See Chemical Initial/Boundary Conditions (IC/BC). We used to support CAM-chem and MOZART4GEOS5 outputs used by WRF-Chem, but this support is deprecated. We recommend running global GEOS-Chem instead. But we use a modified but similar version of
mozbc, so you can use CAM-chem/MOZART4GEOS5 outputs at your own risk.
Do I have to run WRF and GEOS-Chem separately?
No, WRF-GC is an online coupled model just like WRF-Chem. Compile them together, run them together.
Does GEOS-Chem output separately?
No, species are written to the
wrfout_d0... files like WRF-Chem. Species names are different, and generally are the same as GEOS-Chem.
Can I use offline emissions like WRF-Chem?
No, only HEMCO can be used when GEOS-Chem chemistry is used.
Can I run WRF-GC and WRF-Chem in the same WRF install?
No, they must be installed separately. WRF-GC removes all the existing chemistry in WRF-Chem.
I’m sold! How do I get started quickly, as a WRF-Chem user?
You need some GEOS-Chem input files, see Preparing your system. The libraries required for WRF-GC are completely covered by WRF-Chem, so you can reuse the computational environment.
You need to replace the
chemfolder with WRF-GC, see Downloading WRF-GC. Then
./configure -hyb(WRFv3) or
./configure(WRFv4), then you must go to
make install_registry, then go back and
Everything is configured in
No need to prepare emissions input files manually using prep_chem_sources or whatever - HEMCO will do it. Configure emissions using a text file in
Simply run WRF-GC like before -
real.exe, do initial/boundary conditions with our mozbc (Chemical Initial/Boundary Conditions (IC/BC)), then
wrf.exeand off you go.