parameter
description
meaningful
range
comment from
the developers
model
tuning
EPS
perturbation
EPS perturbation
in production
SSO tuning (the tuning of the SSO parameters is dependent on the employed external parameters)
gkwake
low level wake drag constant Cd for blocking
1.5 ±0.5
Very strong dependency on raw data resolution: for ICON-D2 with ASTER data, we use 0.25
switched to multiplicative perturbation in operations at DWD since 2022/05/11
1.5 ±0.5 (additive)
1.5 */ 1.5 (multiplic.)
(ICON glob./EU)
0.25 ±0.1 (additive)
0.25 */ 1.5 (multiplic.)
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
gkdrag
gravity wave drag constant G, a function of mountain sharpness
0.075 ±0.04
Should be zero (turned off) at convection-permitting resolutions
0.16 ±0.04
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
gfrcrit
critical Froude number determining depth of blocked layer Hncrit
0.4 ±0.1
0.425 ±0.1
(ICON glob./EU)
0.333 ±0.1
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
grcrit
critical Richardson number
0.5 (ICON glob./EU)
0.25 (ICON-D2)
tune_minsso
minimal value of SSO-STDH (m) where SSO effects are being considered
default 10
must also be adapted in extpar!
tune_blockred
multiples of the SSO-STDH, above which the SSO-blocking tendency is being reduced proportionally to STDH/z AGL
1.5
default 100 = deactivated
GWD tuning (the tuning of the GWD parameters is dependent on the employed external parameters)
gfluxlaun
variability range for non-orographic gravity wave launch momentum flux
2.50·10-3 ±0.75·10-3
[Pa] relevant for global applications only
3.75·10-3 ±0.75·10-3
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
grid scale microphysics
zvz0i
terminal fall velocity of ice
0.85-1.45 [m/s]
allows temperature bias tuning in the upper tropical troposphere as well as TOA long-wave fluxes
mostly relevant for simulations covering the tropics
0.85 ±0.25
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
zceff_min
minimum value for sticking efficiency
0.01-0.075 [m/s]
tropics
mostly relevant for simulations covering the tropics
v0snow
factor in the terminal velocity for snow
10.0-30.0
recommended value 25.0
identified as "sensitive" for COSMO in
[1]
icesedi_exp
exponent for density correction of cloud ice sedimentation
0.3-0.33
no perturbation recommended
rain_n0fac
multiplicative change of intercept parameter of raindrop size distribution
0.25-4.0
0.1 (ICON-D2)
multiplicative perturbation
identified as "sensitive" for COSMO in
[1]0.1 */ 4.
(ICON glob./EU)
0.1 */ 2.
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
cloud cover
box_liq
Box width for liquid cloud diagnostic in cloud cover scheme
0.05 ±0.02
0.05 ±0.01
(ICON glob./EU)
0.04 ±0.01
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
box_liq_asy
Asymmetry factor for liquid cloud cover diagnostic
2.0-4.0
sensitive to TOA solar fluxes and to a lesser degree long-wave fluxes
3.25 ±0.25
(ICON glob./EU)
4.00 ±0.25
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
thicklayfac
factor for increasing the box width for layer thicknesses exceeding 150 m
0.005 ±0.005 [m-1]
accounting for vertical sub-grid overlap
0.005 ±0.025
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
sgsclifac
Scaling factor for turbulence-induced subgrid-scale contribution to diagnosed cloud ice
0.0-1.0
0.0 turns this contribution off
allow_overcast
Tuning factor for steeper dependence CLC (RH)
=< 1.0
setting allow_overcast < 1 together with a reduction of tune_box_liq_asy causes steeper CLC (RH) dependence. Recommendation: allow_overcast < 1 should not be used in combination with lsgs_cond=.TRUE.
turbulence
q_crit
critical value for normalised super-saturation
1.6-4.0
identified as "sensitive" for COSMO in
[1]1.6 ±1.
(ICON glob./EU)
2.0 ±1.5
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
rlam_heat
scaling factor of the laminar boundary layer for heat (scalars), the change in rlam heat is accompanied by an inverse change of rat_sea in order to keep the evaporation over water (controlled by rlam heat·rat sea) the same
10.0 ±8.0
additive perturbation. Recommendation: the product of rlam_heat and rat_sea should not be significantly larger than 10. Otherwise, there will be too little evaporation over the oceans.
identified as "sensitive" for COSMO in
[1]10.0 ±8.0
(ICON glob./EU)
10.0 ±2.5
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
rat_sea
controls latent and heat fluxes over water
0.8-10.0
lower values increase latent and sensible fluxes over water; different values in data_turbulence.f90 and turb_data.f90?
identified as "sensitive" for COSMO in
[1]perturbed depending on rlam_heat to guarantee
rlam_heat*rat_sea=8.
at all times
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
a_hshr
Length scale factor for the separated horizontal shear mode
1.0 ±1.0
2.0 ±1.0
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
a_stab
factor for stability correction of tur- bulent length scale
0.0
turned off by default because it degrades global
skill scores
identified as "sensitive" for COSMO in
[1]0.0 + 1.0
(ICON glob./EU &
ICON-D2)
only one direction
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
c_diff
length scale factor for vertical diffu- sion of TKE
0.1-0.4
multiplicative perturbation
0.2 */ 2.0
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
alpha0
lower bound of velocity-dependent Charnock parameter
0.0123-0.0335
additive ensemble perturbation of Charnock- parameter
alpha1
parameter scaling the molecular roughness of water waves
0.1-1.0
lower values increase latent and sensible fluxes over water, particularly at low wind speeds. alpha1=1.0
in data_turbulence.f90
and alpha1=0.75 in
turb_data.f90, recommended value: 0.125
tur_len
asymptotic maximal turbulent distance
500 alpha ±150 [m]
identified as "sensitive" for COSMO in
[1]500 ±150
(ICON glob./EU)
300 ±50
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
tkhmin
scaling factor for minimum vertical diffusion coefficient for heat and moisture
0.75 ±0.2
identified as "sensitive" for COSMO in
[1]0.6 ±0.2
(ICON glob./EU)
0.5 ±0.1
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
tkmmin
scaling factor for minimum vertical diffusion coefficient for momentum
0.75 ±0.2
identified as "sensitive" for COSMO in
[1]0.75 ±0.2
(ICON glob./EU)
0.75 ±0.15
(ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
tkred_sfc
multiplicative change of reduction of minimum diffusion coefficients near the surface
0.25-4.0
multiplicative perturbation
default */4.
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
TERRA
c_soil
evaporating fraction of soil
1.0 ±0.25
identified as
"sensitive" for COSMO in
[1]
1.25 ±0.25
(ICON glob./EU)
TLE-MVE
ICON glob. EPS
ICON-EU-EPS
cwimax_ml
scaling parameter for maximum interception storage
5·10-7-5·10-4
low values (<10-6) turn off interception layer.
multiplicative perturbation
5·10-4 */2.
ICON glob. EPS
ICON-EU-EPS
snow cover diagnosis
minsnowfrac
Lower limit of snow cover fraction to which melting snow is artificially reduced in the context of the snow-tile approach
0.2 ±0.1
0.2 ±0.1
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
radiation
dust_abs
Tuning factor for enhanced LW absorption of mineral dust in the Saharan region
0.0
Reduces bias over Sahara for the RRTM scheme but not necessary and implemented with ecRad and itype lwemiss=2
convection
entrorg
Entrainment parameter in convection scheme valid for dx=20km
1.95·10-3 ±0.2·10-3
corresponds to entr_sc in the shallow convection part of COSMO Tiedtke scheme
1.95·10-3 ±0.2·10-3
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
rdepths
maximum allowed shallow convection depth
2.0·104 ±5.0·103 [Pa]
2.0·104 ±5.0·103
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
rprcon
coefficient for conversion of cloud wa- ter into precipitation
1.4·10-3 ±0.25·10-3
1.4·10-3 ±0.25·10-3
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
capdcfac_et
fraction of CAPE diurnal cycle correction applied in the extratropics
0.5 ±0.75
0.5 ±0.75
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
capdcfac_tr
fraction of CAPE diurnal cycle correction applied in the tropics
0.5 ±0.75
0.5 ±0.75
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
lowcapefac
Tuning parameter for diurnal-cycle correction in convection scheme: re- duction factor for low-cape situations
1.0 ±0.5
negpblcape
Tuning parameter for diurnal-cycle correction in convection scheme: maximum negative PBL CAPE allowed in the modified CAPE closure
-500.- 0.
rhebc_land
RH threshold for onset of evaporation below cloud base over land
0.825 ±0.05 [m/s]
tropics; 0.75 as default in code
0.825 ±0.05
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
rhebc_ocean
RH threshold for onset of evaporation below cloud base over sea
0.85 ±0.05 [m/s]
0.85 ±0.05
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
rhebc_land_trop
RH threshold ... over tropical land
0.70 ±0.05
tropics
mostly relevant for simulations covering the tropics
0.70 ±0.05
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
rhebc_ocean_trop
RH threshold ... over tropical sea
0.76 ±0.05 [m/sec]
tropics
identified as "sensitive" for COSMO in
[1]0.75 ±0.05
(ICON glob./EU)
ICON glob. EPS
ICON-EU-EPS
rcucov
Convective area fraction used for computing evaporation below cloud base
0.075
0.05 coded as default
rcucov_trop
Convective area fraction used for computing evaporation below cloud base
0.03
tropics
identified as "sensitive" for COSMO in
[1]
texc
Excess value for temperature used in test parcel ascent
0.125 ±0.05 [K]
0.125 ±0.05
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS
qexc
Excess fraction of grid-scale QV used in test parcel ascent
0.0125 ±0.005 [kg/kg]
0.0125 ±0.005
(ICON glob./EU &
ICON-D2)
ICON glob. EPS
ICON-EU-EPS
ICON-D2-EPS