The purpose of this page is to document the procedure for adding support for new atmosphere grids. The process should be the same for new uniform resolutions as well as for new regionally-refined meshes, although some settings will need to be changed for new regionally-refined mesh configurations. This page is a work in progress, and will be updated as this process is refined and (eventually) made more automated. This documentation is an update of a document written by Mark Taylor and Colin Zarzycki, available as a Google Doc here.
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Archives of already-created grid and mapping files can be accessed at https://web.lcrc.anl.gov/public/e3sm/mapping/grids/ and https://web.lcrc.anl.gov/public/e3sm/mapping/maps/ . This page focuses on creating new versions of these files.
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Step 2: Generate the atmosphere initial condition
Two options are now available to generate the atmosphere initial condition. The first method is document on the page: Generate atm initial condition from analysis data. The second method is documented here in the section Spinning up the atmosphere.
Option 1: Generate atm initial condition from analysis data
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There are two general approaches to generating a new atmospheric initial condition file: remapping an existing initial condition file or remapping reanalysis data. Both of these situations can be addressed with the new HICCUP tool.
Generating atmosphere initial condition data using HICCUP
The procedure to generate new initial conditions (outlined here) has been built into into the HICCUP tool (see https://github.com/E3SM-Project/HICCUP ). HICCUP is a set of flexible and robust python routines to automate and streamline the task of generating a new atmospheric initial condition for E3SM. Most of these routines are essentially wrappers to NCO commands, but there are also routines that directly modify the data using xarray. HICCUP is setup to use ERA5 reanlaysis data or regrid an existing atmospheric initial condition file (either horizontal, vertical, or both). HICCUP includes a surface adjustment routine that follows the original adjustment routine published by ECMWF, which was also reproduced in similar tools by Jerry Olson and Wuyin Lin. HICCUP was built with code readability and documentation as a top priority and includes some unit tests. HICCUP has also successfully been used to generate initial conditions for ne1024 grids using large memory analysis nodes available at HPC centers. Development of HICCUP is ongoing and new features are planned, so any feedback or feature requests are welcome.
The spin-up procedure described below is often not needed when using an initial condition derived from ERA5 reanalysis. However, for certain situations a series of spin-up simulations is required for stability. An example of this is when an RCE initial condition needs to be produced from an aqua planet initial condition.
Spinning up the atmosphere
The following procedure is copied from the recommendations in Mark and Colin's Google Doc https://docs.google.com/document/d/1ymlTgKz2SIvveRS72roKvNHN6a79B4TLOGrypPjRvg0/edit on running new RRM configurations (TODO: clean this up and update):
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land grid descriptor file in SCRIP format
ESMF_RegridWeightGen
geographic distribution for each land surface type along with grid descriptor files for each of those surface types
mkmapdata.sh (found in components/elm/tools/mkmapdata/)
mksurfdata.pl (found in components/clm/tools/clm4_5/mksurfdata_map/)
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