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Combining boundary conditions in REAL case

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Pechudin

Member
Hello beautiful community,

so, I've been wanting to run some idealized simulations with nesting. One way to do that would be to modify an idealized case, but that seems like a lot of work. Another case would be to modify:
  • the input files (ERA5 in this case)
  • the static fields (geo_em files)
In my case, I want to put a long, uniform-profile mountain in a large, flat domain and nest several smaller domains around the mountain. I managed to substitute real ERA5 input data with a horizontally homogeneous sounding (basically extracted a profile from a point and set the entire dataset equal to it). I also adjusted the surface fields to conform to the new domain (meaning, set stuff like LANDMASK to 1 everywhere, set LANDUSE, LAI, soil moisture etc. to constant, height manipulation etc). All went through ungrib and metgrid, real processed it and wrf seems to run it.

Since the boundary conditions in this case are constant, this induces some reflections. However, the WRF description document says that (for real cases) "specified" boundary conditions can be mixed and matched with "open", "periodic" etc. boundary conditions. My questions are then:
  1. Is this possible? Does e.g. periodic x-condition overwrite the "specified" x-conditions?
  2. Am I torturing the model too much and should instead look into models more suited to these kinds of manipulations?
Thank you in advance for your answers to this (admittedly vague) question. I will run tests anyway, as this is quite fun. My plan was to run the simulation until any kind of unphysical reflection or disturbance reached the innermost domain (which would be very small compared to the outer domain).
 
I apologize, in the manual it says that specified conditions on the coarsest grid must be on all four sides. Cheers. I guess I could combine periodic and open conditions on different sides.
 
Pechudin said:
I apologize, in the manual it says that specified conditions on the coarsest grid must be on all four sides. Cheers. I guess I could combine periodic and open conditions on different sides.
Click to expand...
Hi,
Does this mean that your question is resolved and you no longer need assistance?
 
kwerner said:
Hi,
Does this mean that your question is resolved and you no longer need assistance?
Click to expand...

Pretty much yes. I managed to make a flat domain with constant lower conditions (temperature, roughness length etc.) and it seems like the solution is physical. I decided to use all open conditions and just terminate the simulation if the disturbance reaches the inflow edge.

Until that moment the open boundary acts akin to the inflow (or specified) lateral boundary.
 
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