real.exe fails due to configuration of lateral boundary conditions

[georgelimpert]

Hello,

I am attempting to run WRF with specified lateral boundary conditions at southern and western lateral boundaries, but open lateral boundary conditions at the northern and eastern lateral boundaries. To achieve this, I've set the following options in my namelist.input:

 &bdy_control
 spec_bdy_width                      = 5,
 open_xe                             = .true.
 open_ye                             = .true.
 specified                           = .true.
 /

I'm indicating that I want to use specified lateral boundary conditions, except that I want the east and north lateral boundaries to be open. I have just a single domain, and the specified lateral boundary conditions are derived from the NARR. After configuring the rest of my namelist correctly, I attempted to run real.exe. Here is the final section of the rsl.error.000 file:

*************************************
REAL_EM V4.0 PREPROCESSOR
 *************************************
 Parent domain
 ids,ide,jds,jde             1          950            1          900
 ims,ime,jms,jme            -4          126           -4          120
 ips,ipe,jps,jpe             1          119            1          113
 *************************************
DYNAMICS OPTION: Eulerian Mass Coordinate
   alloc_space_field: domain             1 ,                 663458608  bytes allocated
d01 2013-07-01_00:00:00  Yes, this special data is acceptable to use: OUTPUT FROM METGRID V4.0
d01 2013-07-01_00:00:00  Input data is acceptable to use: met_em.d01.2013-07-01_00:00:00.nc
 metgrid input_wrf.F first_date_input = 2013-07-01_00:00:00
 metgrid input_wrf.F first_date_nml = 2013-07-01_00:00:00
d01 2013-07-01_00:00:00 Timing for input         29 s.
d01 2013-07-01_00:00:00          flag_soil_layers read from met_em file is  1
Max map factor in domain 1 =  1.01. Scale the dt in the model accordingly.
  *** Error in boundary condition specification
  boundary conditions at xs             1
  boundary conditions at xe             2
  boundary conditions at ys             1
  boundary conditions at ye             2
  boundary conditions logicals are
  periodic_x     F
  periodic_y     F
  symmetric_xs   F
  symmetric_xe   F
  symmetric_ys   F
  symmetric_ye   F
  open_xs        F
  open_xe        T
  open_ys        F
  open_ye        T
  polar          F
  nested         F
  specified      T
-------------- FATAL CALLED ---------------
FATAL CALLED FROM FILE:  <stdin>  LINE:     165
 *** Error in boundary condition specification
-------------------------------------------

It definitely appears that the issue is due to how I'm trying to configure the lateral boundaries. I suspect that the issue is that while it's possible to mix open, symmetric, and periodic lateral boundary conditions for a domain, it seems that I might only be able to use specified lateral boundary conditions for all of the lateral boundaries.

So, I suppose I'll start by asking this: Can I actually run real.exe (and by extension, WRF-ARW) in this configuration, where the southern and western lateral boundaries are specified, but the eastern and northern lateral boundaries are open?

And if that's possible, any guidance on how to accomplish this would be greatly appreciated.

Thank you for your time and any help you can offer -- even if it's not actually possible to run WRF in this configuration.

 

[kwerner]

Hi,
According to the internal code, which can be found in share/module_bc.F, it's not possible to use open BCs with specified BC's. The exception is that on the west/east sides, you can do this if you're also using periodic conditions. Unfortunately to manipulate this would take more than just modifying this section of the code. Specified BCs are hard-coded to do things at all boundaries, and deactivating this would take a great deal of code modification.