Fine horizontal grid resolution


Hello all,

I wonder whether there is a limit (or a recommended range) to the horizontal grid resolution of CMAQ.

We will be able to obtain meteorological forecasting data of 600m and 200m horizontal grid resolution, for which the 200m data even has LES module turned on. We wish to use them directly as the boundary conditions for CMAQ. We are thus curious whether it is recommended to do so and what may require our special attention.

It is also useful to know whether similar simulations have been previously tested/done.

Any comment is appreciated.



This is not a topic for which I am an expert, but there are several considerations:

  • horizontal and vertical resolutions must be appropriate for each other;
  • neither the cloud nor the vertical diffusion modules are appropriate at LES scales;
  • temporal resolution of the met forcing data must be appropriate (consider wind-speed as a conversion factor between temporal and spatial resolution, and allow for the fact that the met models tend not to resolve features smaller than 5 DX: is 10 M/S a reasonable upper bound? …then 200M horizontal resolution corresponds to a 100 second met-file temporal resolution.

Better to use a chem-enabled version of your LES met-model…