Output files from MM5 are processed by MCIP to create the I/O API files used in the CCTM. MCIP can also be used to reduce the number of vertical layers. This is sometimes necessary as additional vertical layers greatly increase the required computer resources. The coarse MM5 grid is considered to be the “parent” grid for any nested MM5 domain. Any MCIP domain uses the MM5 domain that is at the same horizontal resolution as a “parent.” The MCIP output grid has two fewer grid cells in each direction than the MM5 domain. In addition, it is recommended that a number of boundary grid cells be eliminated for the domain used by the CCTM. The user may eliminate three or six grid cells on each edge. This must be decided when the grids are defined. Grids must be defined for MM5 and MCIP to ensure that the CCTM domain is large enough to include the area of interest. Defining grids is covered in Chapter 5. You must first identify the desired CCTM domain and resolution and work backwards to establish the MCIPand MM5 domains and resolutions.