Atmospheric Topography Generation


Topography needs to be interpolated from a high resolution USGS file, and then doctored up a bit to allow the model to run stably with the new topography. The tool chain used to compute topography is documented in the following paper:  

There are three main steps in this process:

Step (a) Remap (with cell averaging) 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 physgrid configurations (pg1, pg2, pg3) there is the extra step of generating consistent topo data on both the GLL (dynamics) and pgN (physics) grid. 
Step (c) based on the smoothed topography, compute the SGH and SGH30 surface roughness fields used by some parameterizations

Step (b) requires running the homme_tool's smoothing algorithm.  The namelist should be edited to specify the resolution (NE value) or grid file (RRM) grid and the amount of smoothing
Detailed instructions depend on which version of the model is being used: