[Wrf-users] Big cfl errors at beginning of timestep

[afwande juliet]

Dear WRF users,
I have been running WRF model for past 4weeks continuously.
Now when I do the run, I get big values for the cfl errors. Even when I
reduce timestep to as low  as 3*dx, I still get the cfl error with big
values . This happens immediately the first time integration.  Previously
the run were fine and was able to do 6years successfully using ERA
-interim.

d01 1988-02-01_00:30:00 MAX AT i,j,k: 4 2 40 vert_cfl,w,d(eta)= 7.145714
-25.96785 9.4717517E-03

d01 1988-02-01_00:30:00 377 points exceeded cfl=2 in domain d01 at time
1988-02-01_00:30:00 hours

d01 1988-02-01_00:30:00 MAX AT i,j,k: 5 2 41 vert_cfl,w,d(eta)= 10.26220
-16.27522 8.7547116E-03

Timing for main: time 1988-02-01_00:33:20 on domain 1: 0.67898 elapsed
seconds

d01 1988-02-01_00:33:20 528 points exceeded cfl=2 in domain d01 at time
1988-02-01_00:33:20 hours

d01 1988-02-01_00:33:20 MAX AT i,j,k: 4 2 40 vert_cfl,w,d(eta)= 33.15524
-73.26998 9.4717517E-03

d01 1988-02-01_00:33:20 230 points exceeded cfl=2 in domain d01 at time
1988-02-01_00:33:20 hours

d01 1988-02-01_00:33:20 MAX AT i,j,k: 10 1 33 vert_cfl,w,d(eta)= 2.872805
-1.684849 1.5666291E-02

d01 1988-02-01_00:33:20 105 points exceeded cfl=2 in domain d01 at time
1988-02-01_00:33:20 hours

d01 1988-02-01_00:33:20 MAX AT i,j,k: 12 1 33 vert_cfl,w,d(eta)= 2.867926
-2.430345 1.5666291E-02

Timing for main: time 1988-02-01_00:36:40 on domain 1: 0.22810 elapsed
seconds

Below is my physics and domain settings. Same settings I have used in
previous run without any problem.

&physics
 mp_physics                          = 6,
 ra_lw_physics                       = 4,
 ra_sw_physics                       = 4,
 radt                                = 30,
 sf_sfclay_physics                   = 1,
 sf_surface_physics                  = 2,
 bl_pbl_physics                      = 1,
 bldt                                = 0,
 cu_physics                          = 1,
 cudt                                = 5,
 kfeta_trigger                       = 2,
 cu_rad_feedback                     = .true.,
 isfflx                              = 1,
 sst_update                          = 1,
 tmn_update                          = 1,
 sst_skin                            = 1,
 bucket_mm                           = 100.0,
 bucket_J                            = 1.e9,
 ifsnow                              = 1,
 icloud                              = 1,
 surface_input_source                = 1,
 num_soil_layers                     = 4,
 sf_urban_physics                    = 0,



&domains
 time_step                           = 180,
 time_step_fract_num                 = 0,
 time_step_fract_den                 = 1,
 max_dom                             = 1,
 e_we                                = 250,
 e_sn                                = 150,
 e_vert                              = 51,
 p_top_requested                     = 5000,
 num_metgrid_levels                  = 38,
 num_metgrid_soil_levels             = 4,
 dx                                  = 36000, 12000,  3333.33,
 dy                                  = 36000, 12000,  3333.33,
 grid_id                             = 1,
 parent_id                           = 1,
 i_parent_start                      = 1,
 j_parent_start                      = 1,
 parent_grid_ratio                   = 1,
 parent_time_step_ratio              = 1,
 feedback                            = 1,
 smooth_option                       = 0,
!sfcp_to_sfcp                        =.true.,
!use_surface                         = .true.,



Could the problem related to running model for 4weeks without stoping model
to relax.?
I really don't know where problem is.
I got some online info from WRF FAQ  Q8 here but didn't understand or got
confused
http://www2.mmm.ucar.edu/wrf/users/FAQ_files/FAQ_wrf_physics.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/wrf-users/attachments/20151202/786ad2e0/attachment.html