Back to Example List

TERRAIN in 1-way /2-way nested mode

The nested mode is controlled by NSTTYP

• NSTTYP = 2 : 2-way nested model
  • Ratio between mother and child domain MUST be 3:1
  • Number of grid points for a nest therefore must be 3x+1 (where x is any integer value)
  • Feedback between mother and child domain will ensure consistent terrain over nested area
  • Program will check to ensure that the mother:child ratio is 3:1
    
• NSTTYP = 1 : 1-way nested model
  • Ratio between mother and child domain must be an integer. Recommend no bigger than 6:1.
  • Number of grid points for a nest therefore must be Ax+1 (where x is any integer value, and A is the grid ratio)
  • No feedback is performed between mother and child domains 
     

Domain 1 always needs to have NSTTYP=1.

I set NSSTTYP to 1, but I used a 3:1 ratio between model domains, does it mean I cannot run MM5 with 2-way nested option later on? Although it is never recommenced that you run MM5 with 2-way nested option it you run TERRAIN with 1-way nested option, you can do it as long as the mother:child ratio is 3:1. The only difference will be that the terrain feedback between mother and child domain did not take place, and that you run the risk of having inconsistent terrain information over the nest area. If you run TERRAIN as a 1-way nested run, and the mother:child ratio was 5:1, YOU CANNOT RUN MM5 AS A 2-WAY NESTED RUN.