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There are three main steps in this process:
Step (a) downscale dowsample USGS topography data to the atmosphere grid
Step (b) apply dycore-specific smoothing to reduce the amount of gravity wave noise if the topography is too rough. This is a tunable parameter, and a rigorous analysis probably needs to be performed to determine the optimal tuning parameter for future very-high-resolution atmosphere grids. For pg2 grids there is the extra step of generating consistent topo data on both the GLL (dynamics) and pg2 (physics) grid.
Step (c) based on the smoothed topography, compute the SGH and SGH30 surface roughness fields used by some parameterizations
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