[Wrf-users] Exceeded cfl=2 at the corners of the domain

Wang, Yaoping wang.3866 at buckeyemail.osu.edu
Wed Mar 30 19:04:52 MDT 2016


Hello,


I am new to WRF and am setting up a run over the North American domain at 30km resolution. But I keep getting "exceeded cfl=2". After testing various time steps it seems that the error keep occurring at the corners of my domain. I also checked the wind speeds and divergence in the input meteorological data, but did not find any clear outlier models. Could anyone give some suggestions as to what can be done to solve the problem?


The trials and errors:

time step = 180s

d01 1967-01-01_00:00:00         5537 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:          283          42           2 vert_cfl,w,d(eta)=  2.4396536E+07            NaN  9.9999905E-03
d01 1967-01-01_00:00:00         1906 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:           21         190          20 vert_cfl,w,d(eta)=   1102.228      -6444.851      3.5938144E-02
Timing for main: time 1967-01-01_00:03:00 on domain   1:   15.48090 elapsed seconds


time step = 90s

d01 1967-01-01_00:00:00         6080 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:          283          46          29 vert_cfl,w,d(eta)=   6955.001     -1.8047905E+15  9.2214663E-03
d01 1967-01-01_00:00:00         1969 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:          278          56          21 vert_cfl,w,d(eta)=   2879.670       56544.66      3.2001421E-02
Timing for main: time 1967-01-01_00:01:30 on domain   1:   13.09157 elapsed seconds


time step = 30s, namelist.input &domains  smooth_cg_topo = .true.

d01 1967-01-01_00:00:00         5537 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:          283          42           2 vert_cfl,w,d(eta)=  2.4396536E+07            NaN  9.9999905E-03
d01 1967-01-01_00:00:00         1906 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:           21         190          20 vert_cfl,w,d(eta)=   1102.228      -6444.851      3.5938144E-02


time step = 10s, namelist.input &domains  smooth_cg_topo = .true.

d01 1967-01-01_00:00:00         2548 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:          285         179          23 vert_cfl,w,d(eta)=  8.4951393E+14  2.3136813E+23  2.4293438E-02
d01 1967-01-01_00:00:00          987 points exceeded cfl=2 in domain d01 at time 1967-01-01_00:00:00 hours
d01 1967-01-01_00:00:00  MAX AT i,j,k:          285         196          14 vert_cfl,w,d(eta)=   24310.53       372558.9      6.8435431E-02
Timing for main: time 1967-01-01_00:00:10 on domain   1:   15.84628 elapsed seconds


The namelist.input file:

 &time_control
 run_days                            = 3,
 run_hours                           = 0,
 run_minutes                         = 0,
 run_seconds                         = 0,
 start_year                          = 1967,
 start_month                         = 01,
 start_day                           = 01,
 start_hour                          = 00,
 start_minute                        = 00,
 start_second                        = 00,
 end_year                            = 1967,
 end_month                           = 01,
 end_day                             = 04,
 end_hour                            = 00,
 end_minute                          = 00,
 end_second                          = 00,
 interval_seconds                    = 21600
 input_from_file                     = .true.
 history_interval                    = 60,
 frames_per_outfile                  = 1000,
 restart                             = .false.,
 restart_interval                    = 5000,
 io_form_history                     = 2
 io_form_restart                     = 2
 io_form_input                       = 2
 io_form_boundary                    = 2
 debug_level                         = 0
 /

 &domains
 time_step                           = 10,
 time_step_fract_num                 = 0,
 time_step_fract_den                 = 1,
 max_dom                             = 1,
 s_we                                = 1,
 s_sn                                = 1,
 s_vert                              = 1,
 e_we                                = 290,
 e_sn                                = 200,
 e_vert                              = 30,
 p_top_requested                     = 5000,
 num_metgrid_levels                  = 27,
 num_metgrid_soil_levels             = 4,
 dx                                  = 30000,
 dy                                  = 30000,
 grid_id                             = 1,
 parent_id                           = 1,
 i_parent_start                      = 1,
 j_parent_start                      = 1,
 smooth_option                       = 0
 smooth_cg_topo = .true.
 /

 &physics
 mp_physics                          = 3,
 ra_lw_physics                       = 1,
 ra_sw_physics                       = 1,
 radt                                = 30,
 sf_sfclay_physics                   = 1,
 sf_surface_physics                  = 2,
 bl_pbl_physics                      = 1,
 bldt                                = 0,
 cu_physics                          = 1,
 cudt                                = 5,
 isfflx                              = 1,
 ifsnow                              = 1,
 icloud                              = 1,
 surface_input_source                = 1,
 num_soil_layers                     = 4,
 sf_urban_physics                    = 0,
 /

 &fdda
 /

 &dynamics
 w_damping                           = 0,
 diff_opt                            = 1,
 km_opt                              = 4,
 diff_6th_opt                        = 0,
 diff_6th_factor                     = 0.12,
 base_temp                           = 290.
 damp_opt                            = 0,
 zdamp                               = 5000.,
 dampcoef                            = 0.2,
 khdif                               = 0,
 kvdif                               = 0,
 non_hydrostatic                     = .true.,
 moist_adv_opt                       = 1,
 scalar_adv_opt                      = 1,
 /

 &bdy_control
 spec_bdy_width                      = 5,
 spec_zone                           = 1,
 relax_zone                          = 5,
 specified                           = .true.,
 nested                              = .false.,
 /

 &grib2
 /

 &namelist_quilt
 nio_tasks_per_group = 0,
 nio_groups = 1,
 /


Thank you very much,

Yaoping Wang

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