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 unstructed 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").

Connecitivity file download

A collection of connectivity files can be found on Zenodo. The archive is continually updated as more users inform us about the grids 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. (TempestRemap is available as a part of the E3SM-Unified conda environment. It can also be installed following the instructions provided in its repo.)

For example, 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).

QuickView uses the SCRIP format.