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creating region for limited area simulation using variable mesh


New member
I am interested in running simulations at 3 kms over a defined region. Since running a global simulation is computationally expensive, is it appropriate to define the desired region for limited area simulation using the variable resolution input (say, which is 60 km - 3km)? The desired region lies in the refined region of the variable resolution mesh. Or do I need to use 3-km quasi uniform mesh? Also, is the database from mpas tutorial good enough for generating static fields and initial data from ds083.3 for generating ICs at 3 km?
It's perfectly fine to use a variable-resolution mesh for a regional simulation, and there may be some advantages to extracting a regional domain from a variable-resolution global mesh: the regional mesh will have fine resolution in the interior and coarsen as it approaches the boundaries of the limited-area region, allowing small-scale structures to be filtered out as they propagate to the boundaries (which are typically driven by coarser analyses).

The global time-invariant ("static") geographical datasets for topography height, land use category, etc., that are provided for the MPAS tutorial should be fine for mesh spacing down to ~3 km. Some of these fields (e.g., the GMTED2010 topography height) are on a 30-arc-second lat-lon grid and are aggregated down to the MPAS mesh scale, while others (e.g., monthly climatological vegetation fraction) are on significantly coarser grids and are interpolated to the nominal cell center locations.

The 0.25-degree FNL analyses (ds083.3) should be fine for use as initial and lateral boundary conditions. When interpolating these analyses to a 3-km grid, some small imbalances in the fields may result, but the model will adjust and any noise generated by these initial imbalances should be filtered out during the model spin-up.
Thank you Michael for clarifications! I will extract the region for LAS simulations from variable resolution mesh. I guess spin-up of about 2 days would be good for simulating extreme precipitation episodes