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Revision as of 21:10, 29 June 2017 by JiaweiZhuang (Talk | contribs) (FlexGrid idea)

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NOTE: This page is being actively edited right now and the information might be incomplete.

FlexGrid documentation by Jiawei Zhuang (jiaweizhuang@g.harvard.edu)


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"
  • Will be included in v11-02
Stage 2: Implement custom nested simulations Enable the compile option "NEST=cu" (custom) to allow custom nested simulations.
  • Will be included in v11-02
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:

FlexGrid Stage 1 User's Guide


Set up run directory

Use FlexGrid functionalities

FlexGrid Stage 2 User's Guide

Issues to discuss

FlexGrid implementation details

Source code availability

Utilities for compile flags