Hail calculations

Topics related to current and future physics in the WRF as well as any problems you may have.

Hail calculations

Postby ademeij » Mon Nov 21, 2016 6:17 am

Dear WRF forum community,

I have a few questions regarding hail calculations in WRF and I hope that someone can help me out with this.

I performed a test case for a severe hail event over southern Germany (28 July 2013). During this event hailstones with a diameter up to 8cm were observed.

I performed several test cases by running WRF on two domains (12 x 12 km and 3 x 3 km) with different microphysics and cumulus parameterization options. Spin up time for each run is 2 days. The attached namelist.input shows the settings for which the highest values of GRAUPELNC and HAILNC are calculated. However still far from the observed values.
In ‘Registry.EM_COMMON’ I activated ‘hail_opt’ and recompiled WRF.


First, daily maximum calculated values are:
- for DOMAIN 1: ~3.35 mm for GRAUPELNC and ~3.34e-05 mm for HAILNC.
- for DOMAIN 2: ~0.06 mm for GRAUPELNC and ~1.00e-04 mm for HAILNC.
In general the values for GRAUPELNC and HAILNC are too low. For both the domains I would expect higher values for HAILNC, because I activated this in the Registry.EM_COMMON file.

Second, AFWA_HAIL shows diameter values of 0.15 mm for domain 1 and 2. Far too small compared to the observed values, up to 8cm. Why this large difference in diameter? Also, AFWA_HAIL output does not coincide always with HAILNC or GRAUPELNC output. I would expect that when the model calculates HAILNC or GRAUPELNC it would coincide with AFWA_HAIL.

Playing with ccn_conc and nssl_cccn does not impact the results that much.

Does anyone has similar experiences and does anyone know how to improve hail calculations in WRF? Are there flaws in my namelist.input?

Thank you!
Best regards,
Alexander

----------------------------------------------------------------------------

&time_control
run_days = 5,
run_hours = 0,
run_minutes = 0,
run_seconds = 0,
start_year = 2013, 2013,
start_month = 07, 07,
start_day = 26, 26,
start_hour = 00, 00,
start_minute = 00, 00,
start_second = 00, 00,
end_year = 2013, 2013,
end_month = 07, 07,
end_day = 30, 30,
end_hour = 00, 00,
end_minute = 00, 00,
end_second = 00, 00,
interval_seconds = 21600,
input_from_file = .true., .true.,
history_interval = 60, 60,
frames_per_outfile = 24, 24,
restart = .false.,
restart_interval = 21600,
io_form_history = 2,
io_form_restart = 2,
io_form_input = 2,
io_form_boundary = 2,
io_form_auxhist2 = 2,
auxhist2_outname = "radar_d<domain>.<date>.nc"
auxhist2_interval = 60,
frames_per_auxhist2 = 24,
auxinput4_inname = "wrflowinp_d<domain>",
auxinput4_interval = 360,
io_form_auxinput4 = 2,
debug_level = 0,
/

&domains
time_step = 48,
eta_levels = 1.000, 0.998, 0.997, 0.996,
0.995, 0.994, 0.993, 0.992, 0.991,
0.990, 0.985, 0.980, 0.970, 0.960,
0.900, 0.820, 0.700, 0.544, 0.500,
0.380, 0.228, 0.188,
0.152, 0.069, 0.048,
0.029, 0.014, 0.000,
p_top_requested = 10000,
time_step_fract_num = 0,
time_step_fract_den = 1,
max_dom = 2,
s_we = 1, 1,
e_we = 100, 105,
s_sn = 1, 1,
e_sn = 129, 105,
s_vert = 1, 1,
e_vert = 28, 28,
num_metgrid_levels = 38,
dx = 12000, 3000,
dy = 12000, 3000,
grid_id = 1, 2,
parent_id = 1, 1,
i_parent_start = 1, 38,
j_parent_start = 1, 51,
parent_grid_ratio = 1, 4,
parent_time_step_ratio = 1, 4,
feedback = 1,
smooth_option = 0,
/

&afwa
afwa_diag_opt = 1, 1,
afwa_ptype_opt = 1, 1,
afwa_vil_opt = 1, 1,
afwa_radar_opt = 1, 1,
afwa_severe_opt = 1, 1,
afwa_icing_opt = 1, 1,
afwa_vis_opt = 1, 1,
afwa_cloud_opt = 1, 1,
afwa_therm_opt = 1, 1,
afwa_turb_opt = 1, 1,
afwa_buoy_opt = 1, 1,
afwa_hailcast_opt = 1, 1,
afwa_ptype_ccn_tmp = 268.15,
afwa_ptype_tot_melt = 25,
/

&physics
rdlai2d = .true.,
usemonalb = .true.,
mp_physics = 18, 18, 8, 6, 6, 6, 6,
ra_lw_physics = 5, 5, 4, 4, 4, 4, 4,
ra_sw_physics = 5, 5, 4, 4, 4, 4, 4,
radt = 30, 30, 30, 10, 10, 10, 10,
sf_sfclay_physics = 1, 1, 1, 1, 1, 1, 1,
sf_surface_physics = 2, 2, 1, 2, 2, 2, 2,
bl_pbl_physics = 1, 1, 1, 1, 1, 1, 1,
bldt = 0, 0, 0, 0, 0, 0, 0,
cu_physics = 2, 0, 0, 0, 0, 0, 0,
cudt = 0, 0, 0, 0, 0, 0, 0,
isfflx = 1,
ifsnow = 1,
icloud = 1,
surface_input_source = 1,
num_soil_layers = 4,
num_land_cat = 21,
maxiens = 1,
maxens = 3,
maxens2 = 3,
maxens3 = 16,
ensdim = 144,
prec_acc_dt = 60, 60, 60,
gsfcgce_hail = 1,
gsfcgce_2ice = 0,
hail_opt = 1,
ccn_conc = 0.7E9,
nssl_cccn = 0.7E9,
/

&fdda
/

&dynamics
dyn_opt = 2,
rk_ord = 3,
w_damping = 0,
diff_opt = 0,
km_opt = 1,
damp_opt = 0,
base_temp = 290.,
zdamp = 5000., 5000.,
dampcoef = 0.01, 0.01,
khdif = 0, 0,
kvdif = 0, 0,
smdiv = 0.1, 0.1,
emdiv = 0.01, 0.01,
epssm = 0.1, 0.1,
non_hydrostatic = .true., .true.,
time_step_sound = 4, 4,
h_mom_adv_order = 5, 5,
v_mom_adv_order = 3, 3,
h_sca_adv_order = 3, 5,
v_sca_adv_order = 2, 3,
/

&bdy_control
spec_bdy_width = 5,
spec_zone = 1,
relax_zone = 4,
specified = .true., .false.,
periodic_x = .false., .false.,
symmetric_xs = .false., .false.,
symmetric_xe = .false., .false.,
open_xs = .false., .false.,
open_xe = .false., .false.,
periodic_y = .false., .false.,
symmetric_ys = .false., .false.,
symmetric_ye = .false., .false.,
open_ys = .false., .false.,
open_ye = .false., .false.,
nested = .false., .true.,
/

&grib2
/

&namelist_quilt
nio_tasks_per_group = 0,
nio_groups = 1,
/
ademeij
 
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Joined: Tue Sep 06, 2016 4:49 am

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