[Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
David Ovens
ovens at atmos.washington.edu
Thu Mar 4 14:17:01 MST 2010
All,
Bob's suggestion about using a different smoothing option in geogrid
is the only way I've been able to consistently run at 4/3-km
resolution over a region that covers Whistler, BC. We have to do 5
smoothing passes.
So, in geogrid/GEOGRID.TBL.ARW for all
name = HGT_M
name = HGT_U
name = HGT_V
I have
smooth_option = smth-desmth_special; smooth_passes=5
That has worked very well. We had the same problems trying all of the
other things that Bob mentions.
Note that we run our high resolution run after running ndown.exe, so
we're able to use smooth_passes=1 for the topography of our coarser
domains.
David
--
David Ovens e-mail: ovens at atmos.washington.edu
Research Meteorologist phone: (206) 685-8108
Dept of Atm. Sciences plan: Real-time MM5 forecasting for the
Box 351640 Pacific Northwest
University of Washington http://www.atmos.washington.edu/mm5rt
Seattle, WA 98195 Weather Graphics and Loops
http://www.atmos.washington.edu/~ovens/loops
On Thu, Mar 04, 2010 at 11:47:40AM -0700, Dumais, Bob (Civ, ARL/CISD) wrote:
> Classification: UNCLASSIFIED
> Caveats: NONE
>
> All,
>
> I found this issue as well, over very steep terrain regions.
> For example, I tried running WRF in triple nest to 300 m grid spacing
> over the White Sands Missile Range, Nm area (2.7 km; 900m; 300 m using
> NAM 218 ICs and LBCs). Simply interpolating to 300 m from the default
> USGS 1 km data worked fine. However, trying to run with 300 m terrain
> generated from higher resolution NEDS arc 1 sec data causes the model to
> crash everytime no matter which case/external dataset I try. It always
> happens within the first 2 min of model integration. It looks like a
> singular point blows up/produces an instability where there is a very
> steep model terrain slope. In fact, trying to run a grid recently for
> the Olympic venue region near Whistler, BC the same thing happened. Blow
> ups (CFL violations due to big values of W) in low levels at a single
> steep slope point in the domain, within 2 min of integration. This was
> for a 1 km grid spacing domain where the terrain was generated from the
> default 1 km USGS data! At 3 km grid spacing, the model runs fine.
>
> In the BC domain, I believe the "magic" point where things were
> blowing up was found to be found near 50.13 N and -123.625. It is not a
> boundary point. I have tried very small time steps, different vertical
> grid structures, microphysics, radiation, PBL physics, land surface, 6th
> order diffusion strength, and even divergence damping strength (smdiv in
> namelist). Nothing things to prevent this for the WSMR or Whistler areas
> I mentioned. I am cc'ing Dr Jimy Dudhia this email, since I think he may
> be able to add something regarding this possible model slope issue. I
> notice that in my cases where the instabilities occur, model slopes are
> pretty high and may be approaching 45 deg. My gut feeling is that slope
> may become an issue for some domains at grid spacings about 1 km or
> less. Maybe a different terrain smoothing option in geogrid could help??
> Where are you running your model?
>
>
> Bob
>
> -----Original Message-----
> From: wrf-users-bounces at ucar.edu [mailto:wrf-users-bounces at ucar.edu] On
> Behalf Of Min Zhu
> Sent: Thursday, March 04, 2010 3:34 AM
> To: wrf-users at ucar.edu
> Subject: Re: [Wrf-users] Upper boundary cfl error
>
> Hi,
>
>
>
> It seems that the problem is in lower boundary rather than upper
> boundary. Also your time step seems to be bigger.
>
>
>
> Cheers,
>
>
>
> Min Zhu
>
> Meso-scale Wind Modeller
>
>
>
> D +44 (0)1923 299 360
>
>
>
> RES Group, registered in England and Wales with Company Number 1589961
>
> Registered Office: Beaufort Court, Egg Farm Lane, Kings Langley,
> Hertfordshire WD4 8LR
>
> P please consider the environment - do you really need to print this
> email?
>
>
>
> From: wrf-users-bounces at ucar.edu [mailto:wrf-users-bounces at ucar.edu] On
> Behalf Of Andre Pattantyus
> Sent: 04 March 2010 00:11
> To: wrf-users at ucar.edu
> Subject: [Wrf-users] Upper boundary cfl error
>
>
>
> Hi all,
>
> I am getting these few errors at my upper boundary. Among other things,
> I have tried using the new damping option, diff_opt =2, because I am
> using running towards an LES in my inner domain. A solution seems easy
> but so far my attempts have not yielded success. below is my namelist.
>
>
> 3 points exceeded cfl=2 in domain d03 at time 2006-03-29_12:00:16 hours
> MAX AT i,j,k: 40 80 4 vert_cfl,w,d(eta)= 2.263442993 -80.54151917
> 0.2999961376E-02
> 3 points exceeded cfl=2 in domain d03 at time 2006-03-29_12:00:16
> hours
> MAX AT i,j,k: 40 80 4 vert_cfl,w,d(eta)= 2.485260963 13.09560013
> 0.2999961376E-02
> 3 points exceeded cfl=2 in domain d03 at time 2006-03-29_12:00:16
> hours
> MAX AT i,j,k: 41 80 4 vert_cfl,w,d(eta)= 2.567909241 -117.0119095
> 0.2999961376E-02
> 22 points exceeded cfl=2 in domain d03 at time
> 2006-03-29_12:00:16+08/09 hours
> MAX AT i,j,k: 40 80 4 vert_cfl,w,d(eta)= 6.311451435 -170.4623871
> 0.2999961376E-02
> 36 points exceeded cfl=2 in domain d03 at time
> 2006-03-29_12:00:16+08/09 hours
> MAX AT i,j,k: 40 80 3 vert_cfl,w,d(eta)= 6.109247208 -223.6106720
> 0.2799987793E-02
> AVOST IN VILKA
> ~
> ~
> ~
>
> &time_control
> run_days = 2,
> run_hours = 36,
> run_minutes = 0,
> run_seconds = 0,
> start_year = 2006, 2006, 2006,
> start_month = 03, 03, 03,
> start_day = 29, 29, 29,
> start_hour = 12, 12, 12,
> start_minute = 00, 00, 00,
> start_second = 00, 00, 00,
> end_year = 2006, 2006, 2006,
> end_month = 03, 03, 03,
> end_day = 31, 31, 31,
> end_hour = 00, 00, 00,
> end_minute = 00, 00, 00,
> end_second = 00, 00, 00,
> interval_seconds = 10800
> input_from_file = .true.,.true.,.true.,
> history_interval = 60, 60, 60,
> frames_per_outfile = 1000, 1000, 1000,
> restart = .false.,
> restart_interval = 720,
> io_form_history = 2
> io_form_restart = 2
> io_form_input = 2
> io_form_boundary = 2
> debug_level = 0
> /
>
> &domains
> time_step = 8,
> time_step_fract_num = 0,
> time_step_fract_den = 1,
> max_dom = 3,
> e_we = 121, 169, 241,
> e_sn = 121, 169, 241,
> e_vert = 61, 61, 61,
> p_top_requested = 5000,
> num_metgrid_levels = 40,
> num_metgrid_soil_levels = 4,
> dx = 4500, 1500, 500,
> dy = 4500, 1500, 500,
> grid_id = 1, 2, 3,
> parent_id = 0, 1, 2,
> i_parent_start = 1, 33, 53,
> j_parent_start = 1, 33, 53,
> parent_grid_ratio = 1, 3, 3,
> parent_time_step_ratio = 1, 3, 3,
> feedback = 0,
> smooth_option = 0,
> eta_levels = 1.0000, .9976, .9948, .9920,
> .9890,
> .9858, .9825, .9790, .9754, .9718, .9679, .9637, .9590, .9538, .9480,
> .9415, .9340, .9251, .9144, .9020, .8883, .8736, .8582, .8420, .8253,
> .8079, .7900, .7714, .7523, .7326, .7124, .6915, .6699, .6477, .6248,
> .6015, .5779, .5540, .5300, .5057, .4812, .4566, .4319, .4070, .3822,
> .3576, .3333, .3100, .2881, .2679, .2494, .2316, .2135, .1936, .1707,
> .1445, .1159, .0863, .0569, .0282, .0000, /
>
>
> &physics
> mp_physics = 8, 8, 8,
> ra_lw_physics = 1, 1, 1,
> ra_sw_physics = 2, 2, 2,
> radt = 4, 4, 4,
> sf_sfclay_physics = 4, 4, 4,
> sf_surface_physics = 3, 3, 3,
> bl_pbl_physics = 4, 4, 4,
> bldt = 0, 0, 0,
> cu_physics = 0, 0, 0,
> cudt = 0, 0, 0,
> isfflx = 1,
> ifsnow = 0,
> icloud = 1,
> surface_input_source = 1,
> num_soil_layers = 6,
> sf_urban_physics = 0,
> maxiens = 1,
> maxens = 3,
> maxens2 = 3,
> maxens3 = 16,
> ensdim = 144,
> slope_rad = 1, 1, 1,
> topo_shading = 1, 1, 1,
> shadlen = 25000.,
> /
>
> &fdda
> /
>
> &dynamics
> w_damping = 1,
> diff_opt = 2,
> km_opt = 4,
> diff_6th_opt = 2, 2, 2,
> diff_6th_factor = 0.12, 0.12, 0.12,
> base_temp = 290.
> damp_opt = 3,
> zdamp = 5000., 5000., 5000.,
> dampcoef = 0.2, 0.2, 0.2
> khdif = 0, 0, 0,
> kvdif = 0, 0, 0,
> non_hydrostatic = .true., .true., .true.,
> moist_adv_opt = 1, 1, 1,
> scalar_adv_opt = 1, 1, 1,
> /
>
> &bdy_control
> spec_bdy_width = 5,
> spec_zone = 1,
> relax_zone = 4,
> specified = .true., .false.,.false.,
> nested = .false., .true., .true.,
> /
>
> &grib2
> /
>
> &namelist_quilt
> nio_tasks_per_group = 0,
> nio_groups = 1,
>
>
>
> --
> Andre Pattantyus, Graduate Student Research Assistant Marine and
> Environmental Systems, Florida Institute of Technology 150 W. University
> Blvd, Melbourne, FL 32901
>
> Phone: (321) 674-8330 | Fax: (321) 674-7212 | Email:
> apattantyus2008 at fit.edu
>
>
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