Two question about mesh resolution and physics setting

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islandowner

New member
I have two questions，the fisrt one is about mesh resolution.
As we know, the resolution in WRF means the size of dx and dy. For MPAS，how to understand the resolution of the MPAS grid？Such as quasi-uniform 60km mesh and variable-resolution 60-3km mesh.
The second one is about physics setting. In the variable-resolution mesh simulation case, such as 60-3km, I want to trun on convction physics in the coarse region and trun off in the refinement region. How do you set these features？

Thank you!

Ignoring map scale factors, in WRF, dx and dy give the distances from one cell center to the next in the x- and y-directions. In MPAS, the mesh resolution is in some sense a generalization of this idea: it's the mean distance between a cell's center and the centers of its neigboring cells. Because MPAS meshes can have variable resolution, the mesh resolution can be thought of as a 2-d, spatially varying field. Actually, when considering map scale factors, the same is true in WRF as well -- the true resolution is a 2-d, spatially varying field.

There is one "scale-aware" convection scheme available in MPAS as part of the "convection_permitting" suite, specifically, the Grell-Freitas scheme. To get an understanding of how this scheme behaves in MPAS, you might have a look at this paper: https://journals.ametsoc.org/doi/abs/10.1175/MWR-D-15-0311.1 . In general, if you'd like to take any other convection scheme in MPAS, and to turn that scheme off as the mesh resolution increases, you'd need to do some model development work. For examples of what this development might look like, you can search for the work that was done on the multi-scale Kain-Fritsch scheme by Kiran Alapaty et al.

Assessment of MPAS variable resolution simulations in the grey-zone of convection against WRF model results and observations
https://docsbay.net/assessment-of-mpas-variable-resolution-simulations-in-the-grey-zone-of-convection-against-wrf-model-results-and-observations