[Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
Dumais, Bob (Civ, ARL/CISD)
robert.dumaisjr at us.army.mil
Thu Mar 4 16:50:00 MST 2010
Classification: UNCLASSIFIED
Caveats: NONE
Thank you , Mark. That is a good suggestion, especially as if you say
the hi res structure stays intact even after 5 passes. I would be
worried if the 5 pass smoothing made 500 m terrain field look more like
a 2 km terrain field after 1 pass. As Sen Chiao mentioned earlier,
without capturing the higher resolution terrain & land use structure,
the impact of a higher resolution grid becomes questionable in most
cases when considering the computational cost involved. Have a great
night-
Bob
-----Original Message-----
From: wrf-users-bounces at ucar.edu [mailto:wrf-users-bounces at ucar.edu] On
Behalf Of Mark Stoelinga
Sent: Thursday, March 04, 2010 3:50 PM
To: wrf-users at ucar.edu
Subject: Re: [Wrf-users] Upper boundary cfl error (UNCLASSIFIED)
I can also confirm what Bob and David suggested...I had the same problem
for 4/3-km simulations, and solved it the same way ( don't recall if we
did 4 or 5 smoothing passes).
What I do recall is that the resultant smoothing of the terrain is not
as drastic as one might fear from 5 smoothing passes. The differences
are noticeable, but most of the hi-res structure in the terrain is still
there. And the WRF crash problem goes away.
Mark
--
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Senior Scientist
3TIER Inc. <http://www.3tier.com/>
3TIER Inc.
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On Mar 4, 2010, at 1:17 PM, David Ovens wrote:
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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Caveats: NONE
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