[Wrf-users] Running global WRF with time varying lower boundary conditions

[Eric Altshuler]

Hello,

I have discovered a problem when running global WRF with time varying lower boundary conditions (sst_update = 1). In the namelist file namelist.input.global in WRFV3/test/em_real, the variable interval_seconds is not specified, and apparently the default value is 43200 seconds (12 hours). Although lateral boundary conditions are not needed when running the global version, the lower boundary condition file(s) (wrflowinp_d*) are needed for each domain if time-varying lower boundary conditions are desired. Accordingly, I added these two lines to the time_control section of the namelist.input.global file

 auxinput4_inname                    = "wrflowinp_d<domain>",
 auxinput4_interval                  = 360,

since I have 6-hourly data available. However, when I run real.exe, the program produces a wrflowinp_d01 file with data only every 12 hours, despite setting auxinput4_interval = 360. I found that it is also necessary to set interval_seconds = 21600 in the namelist.input.global file in order to get 6-hourly lower boundary conditions, even though interval_seconds is supposed to be the interval for lateral boundary conditions (wrfbdy_d01).

It is also necessary to generate WPS output (met_em.d*) for all domains at each time that lower boundary conditions are available, if the user wants to run WRF with time varying lower boundary conditions. The user manual says that when running global WRF then WPS output is only needed for the initial time, but this is not true if time varying LBC are desired.

Finally, the ARW V3 description (tech report) says that the ocean mixed layer option can be used with the 5-layer land surface model option (sf_surface_physics = 1). Is the 5-layer LSM the only one that can be used with the ocean mixed layer option? I generally use the Noah LSM (sf_surface_physics = 2) because my domains of interest cover both land and ocean, and the 5-layer LSM is inadequate for representing land surface physics. Can the ocean mixed layer option be used with the Noah LSM?

Thanks in advance for your feedback.

Best regards,

Eric L. Altshuler
Assistant Research Scientist
Center for Ocean-Land-Atmosphere Studies
4041 Powder Mill Road, Suite 302
Calverton, MD 20705-3106
USA

E-mail: ela at cola.iges.org
Phone: (301) 902-1257
Fax: (301) 595-9793