Activity 3: More about nesting
Note: you should attempt this assignment only after you completed Assignment 2.
You may have noticed that in order to create nests, we also need to define two paramenters in the namelist called:
These two parameters refer to the position in your domain where you would like your nests to be. They refer to the grid point location of your nest relative to its parent. Just be careful when working with them, because you want one nest to be inside the other - without any overlapping - if they receive information from each other! The figure below exemplifies what it is meant by i_parent_start and j_parent_start:
Figure 1 - Illustration from the WRF Users' Guide, page 3-20, on the parameters used when creating a nest.
In the experiment you created in Activity 2, try to change the values for i_parent_start and j_parent_start. Can you create a setup where the nests are more centred over southern Norway?
You may have noticed that you should also define the number of grid points you want for a nest. This is done via the paramenters e_we and e_sn of your namelist.wps. In the WRF Users' Manual, page 3-20, it says:
If you have a ratio of 3:1, what should your e_we and e_sn values be if you want your nests to have:
You are welcome to post any questions on our Facebook group.