MM5 Grids

• The number of rows (NROWS) and columns (NCOLS) should be an even integer.
• The smallest grid domain must contain at least two radiosonde observations.
• Use no more than four grids in a nested grid family simulation.
• Set Delta X equal to Delta Y to maintain accuracy of finite difference schemes.
• External boundary thickness should be set to “0”.
• Horizontal grid spacing for the MM5 nested grids generally have a 3:1 ratio, although a 4:1 ratio has been employed.

CCTM Grids

• A CTM grid uses the same horizontal resolution as its MM5 parent grid.
• Minimum grid dimensions of 30 rows and 30 columns are recommended.
• External boundary thickness should be set to “1”.
• A CCTM grid should be smaller than its parent MM5 grid by at least four grid cells and preferably by six.