Strategies
Domains
As a characteristic of the model, MC2 can be run in a series of cascades using data from a previous run to nest a subsequent run of the model. Before relaunching MC2 on a subsequent run, we select a subdomain of interest within the domain of the previous run and define, on that subdomain, a grid at higher resolution. This self-nesting capability of the MC2 modelling system becomes very important when we try to run the model at very high resolution (up to 1 km) starting with initial analysis available only at much coarser resolution.
Nesting Strategies: |
A: 50 km grid => | B: 15 km grid => | C: 4 km grid => | D: 1 km grid |
The MC2 computational domains in this study are discretized using Nx x Ny x Nz points on a rectangular tensor-product grid. Resolution of each domain is uniform in each horizontal direction and the number of grid points in the vertical direction is typically one order of magnitude smaller than in the horizontal. Each of the domains can be seen in detail below :
Click theletter on the map to zoom in on each domain:
In this demonstration, we selected a case on July 14 , 1997 and show you how MC2 performs under the strategies. See Output.
Initial Conditions and Boundary Conditions
The 50 km resolution run is based on the initial conditions of an objective analysis of the SEF global model from 00Z July 14 to 06Z July 15, 1997. However the initial conditions for 15 km, 4 km or 1 km resolution run are derived from the previous run as a part of the self-nesting strategies. Lateral boundary conditions are derived either from the SEF global model (for 50 km run) or from the output of previous run within each of the limited area domains (for 15 km, 4 km and 1 km runs).
Restart Time Flow-Chart for Self-nesting
In the self-nesting process, each restart time is designed later than previous run's start time to reduce initial fields errors. In each run the meteorological fields need to be initialized to dynamic balance, and moreover, need time to spin-up. Clearly, at the start og a runthe meteorological fields are not suitable as nesting fields for the higher resolution runs.
