FlexGrid
NOTE: This page is being actively edited right now and the information might be incomplete.
FlexGrid documentation by Jiawei Zhuang (jiaweizhuang@g.harvard.edu)
Overview
FlexGrid is a new functionality in GEOS-Chem v11-02 to unify all metfield I/O routines by HEMCO.
HEMCO's interface and regridding&cropping capability allow users to
- Set up a nested simulation over any custom domains without changing model's source code.
- Explicitly control each meteorological variable in run-time configuration files to perform metfield experiments (an interface resembling GCHP).
FlexGrid idea
Setting up a new nested domain should be extremely easy. In theory, it simply requires
- New metfields over that domain
- New regional emission data sets if necessary
- Tunning several domain-dependent or resolution-dependent parameters.
There's no reason that one has to touch the model source code. However, in previous versions, all nested domains were hard-coded so users need to do a lot of tedious coding in order to set up a new domain. The major trouble was metfield I/O, as we assumed that the model grid exactly matches the metfield grid.
FlexGrid implementation plan
The table below shows the implementation plan for FlexGrid:
| Stage | Detail | Status |
|---|---|---|
| Stage 1: Read metfields by HEMCO | Enable the compile option "MET=flexgrid" to read any NetCDF-format metfields through HEMCO. This unifies "MET=geosfp" and "MET=merra2" |
|
| Stage 2: Implement custom nested simulations | Enable the compile option "NEST=cu" (custom) to allow custom nested simulations. |
|
| Stage 3: Grid-independent GEOS-Chem classic | Unify compile options "GRID=xxx" by moving all grid size parameters and resolution-dependent parameters to run-time configuration files. | No specific plan right now. Need to be traded off against the nested-GCHP development. |
FlexGrid for different types of users
Users with different research focuses and different computational resource available can get different benefits from FlexGrid: