Connectivity files ¶

The horizontal grids used by E3SM's atmosphere component EAM, and sometimes the land component ELM as well, are cubed spheres. Since these are unstructured grids from ParaView's perspective, QuickView needs to know how to map data to the globe. Therefore, for each simulation data file, a "connectivity file" needs to be provided.

In EAMv2, v3, and v4, most of the variables (physical quantities) are written out on a "physics grid" (also referred to as "physgrid", "FV grid", or "control volume mesh") described in Hannah et al. (2021). The naming convention for such grids is ne*pg2, with * being a number, e.g., 4, 30, 120, 256, 1024. Further details about EAM's cubed-sphere grids can be found in EAM's documentation, for example in this overview and this description.

Future versions of QuickView will also support the cubed-sphere meshes used by EAM's dynamical core, i.e., the ne*np4 grids (also referred to as "native grids" or "GLL grids").

Connectivity file download ¶

Collections of connectivity files can be found on Zenodo for quasi-uniform meshes and regionally refined meshes. These collections are continually updated as more users inform us about the grids they use.

Generating connectivity files ¶

Users can generate connectivity files with TempestRemap (Ullrich and Taylor, 2015; Ullrich et al., 2016) using this script shared by Mark A. Taylor at Sandia National Laboratories.

Paths in Mark's script

Before using Mark's script, please set exepath therein to where TempestRemap is installed and change wdir to the location where the newly generated connectivity files should be written to.

TempestRemap

TempestRemap is available as a part of the E3SM-Unified conda environment. It can also be installed following the instructions provided in its repo.

Quasi-uniform meshes ¶

Using Mark's script, the command

./makeSE.sh 30

will generate several different files for the ne30pg2 grid, including, e.g.,

TEMEPST_NE30pg2.g (Exodus format),
TEMPEST_ne30pg2.scrip.nc (SCRIP format).

The QuickView family uses the SCRIP format.

Regionally refined meshes ¶

Each configuration of the E3SM Regionally Refined Model (RRM, see, e.g., Tang et al., 2023) has a corresponding grid file in the Exodus format (a .g file). The .g file can be used to generate the SCRIP-format connectivity file needed by the QuickView family.

For example, a connectivity file for the NARRM grid described in Tang et al., 2023 can be generated using Mark's script via the following command, assuming the paths in the script have been adapted as needed and the grid file northamericax4v1.g is available in the current directory:

./makeSE.sh northamericax4v1.g