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Slope and topography shading do not show any difference

gpriftis

New member
I am running a 3 domain (9- ,3- ,1-km) WRF simulation for the month of August 2020, centered over the island of Java in Indonesia. The mountains over island are higher than 2.5 km. However, there is not difference in the shortwave downward shortwave radiation (SWDOWN) when I turn on the slope_rad and topo_shading flags. I have attached the elevation map, as well as 2 maps of the SWDOWN with and without the slope shading flag.

I am trying to figure out why I don’t see any difference. Any ideas/suggestions would be very helpful.

Thank you !

Here is the namelist:

&time_control
start_year = 2020, 2020, 2020
start_month = 08, 08, 08
start_day = 01, 01, 01
start_hour = 00, 00, 00
start_minute = 00, 00, 00
start_second = 00, 00, 00
end_year = 2020, 2020, 2020
end_month = 08, 08, 08
end_day = 01, 01, 01
end_hour = 06, 06, 06
end_minute = 00, 00, 00
end_second = 00, 00, 00
interval_seconds = 21600,
input_from_file = .true., .true., .true.
history_interval = 60, 60, 60
frames_per_outfile = 24, 24, 24
restart = .false.,
restart_interval = 1440,
io_form_history = 2
io_form_restart = 2
io_form_input = 2
io_form_boundary = 2
debug_level = 0
/

&domains
time_step = 15,
time_step_fract_num = 0,
time_step_fract_den = 1,
max_dom = 3,
e_we = 246, 370, 301
e_sn = 246, 202, 121
e_vert = 69, 69, 69
p_top_requested = 5000,
num_metgrid_levels = 34,
num_metgrid_soil_levels = 4,
dx = 9000, 3000, 1000
dy = 9000, 3000, 1000
grid_id = 1, 2, 3
parent_id = 1, 1, 2
i_parent_start = 1, 61, 100
j_parent_start = 1, 74, 50
parent_grid_ratio = 1, 3, 3
parent_time_step_ratio = 1, 3, 3
feedback = 1,
smooth_option = 0,
eta_levels = 1. , 0.9975278 , 0.99506141, 0.99260082, 0.99014601, 0.98769697,
0.98525369, 0.98281614, 0.98038433, 0.97795823, 0.97553783, 0.96951170,
0.96352091, 0.95756525, 0.95164453, 0.94575853, 0.93990706, 0.92830686,
0.91684234, 0.9055119 , 0.89431398, 0.88324703, 0.85614264, 0.82982382,
0.80426781, 0.7794525 , 0.75535643, 0.73195875, 0.70923920, 0.68717816,
0.66575651, 0.64495574, 0.62475785, 0.60514536, 0.58610131, 0.56760922,
0.54965309, 0.53221740, 0.49884740, 0.46738373, 0.43771748, 0.40974597,
0.38337238, 0.35850544, 0.33505906, 0.31295210, 0.29210804, 0.27245474,
0.25392417, 0.23645219, 0.21997833, 0.20444557, 0.18980015, 0.17599138,
0.16297146, 0.15069532, 0.13912048, 0.12820688, 0.11791674, 0.10821444,
0.09906640, 0.09044096, 0.08230826, 0.07464016, 0.06741012, 0.06059310,
0.05416552, 0.04810512, 0.0000
/

&physics
mp_physics = 8, 8, 8
ra_lw_physics = 1, 1, 1
ra_sw_physics = 2, 2, 2
radt = 10, 10, 10
sf_sfclay_physics = 2, 2, 2
sf_surface_physics = 2, 2, 2
bl_pbl_physics = 2, 2, 2
bldt = 0, 0, 0
cu_physics = 5, 5, 5
shcu_physics = 1, 1, 1
cu_rad_feedback = .false., .false., .false.
cugd_avedx = 3,
ishallow = 0,
cu_diag = 1, 1, 1
cudt = 5, 5, 5
slope_rad = 1, 1, 1
topo_shading = 1, 1, 1
isfflx = 1,
ifsnow = 0,
icloud = 0,
num_soil_layers = 5,
num_land_cat = 21,
sf_urban_physics = 1, 1, 1
maxiens = 1,
maxens = 3,
maxens2 = 3,
maxens3 = 16,
ensdim = 144,
/

&fdda
/

&dynamics
w_damping = 0,
diff_opt = 1,
km_opt = 4,
diff_6th_opt = 0, 0, 0,
diff_6th_factor = 0.12, 0.12, 0.12,
base_temp = 290.
damp_opt = 0,
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,
diff_6th_slopeopt = 1, 1, 1,
/
use_baseparam_fr_nml = .true.

&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,
/


Java_Elevation.pngWRF_Slope_Off.pngWRF_Slope_On.png
 
Your namelist.input looks fine to me.

Have you looked at radiation at various local times, e.g., early morning, noon, late afternoon etc?

Also, please output the variable "ht_shad" to see how large it could be.
 
Thank you for you quick reply Ming. I examined different times throughout the day, morning, noon, etc. but are all the same between the two simulations.
I added the "ht_shad" variable in the output and I have attached the figure below. It is actually exactly the same as the figure with the topography elevation I posted in the initial post.

hgt_shadow.png
 
Thank you for you quick reply Ming. I examined different times throughout the day, morning, noon, etc. but are all the same between the two simulations.
I added the "ht_shad" variable in the output and I have attached the figure below. It is actually exactly the same as the figure with the topography elevation I posted in the initial post.

View attachment 12944
This Domai Average is a little bit different on your pics.
 
ht_shad should be close to ht. The two panels that show ht_shad and terrain height have same pattern and scale. I guess somehow the calculation of domain average value is not correct, but the value used in the model is correct, ---- I won't worry for this issue.

I wonder whether you have output "SWNORM"? I am thinking that this should be the variable that truly reflects the slope impact.

Please take a look and let me know the results.
 
I checked it and looks like you are correct Ming. When the slope effects are off the "SWNORM" is 0. The maximum value is about 200 W/(m2) more than the actual SWDOWN when the slope flag is on. I have attached 3 figures below to demonstrate those differences.
 

Attachments

  • SWDOWN.png
    SWDOWN.png
    113.7 KB · Views: 1
  • SWNORM_slope_off.png
    SWNORM_slope_off.png
    65.3 KB · Views: 1
  • SWNORM_slope_on.png
    SWNORM_slope_on.png
    137.8 KB · Views: 1
My questions would be, does the WRF use the SWNORM to calculate all the fields if the slope flag is on?
All the rest of the variables have exactly the same magnitude.
 
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