Changes in namelists in SURFEX V9.1.0

Minvielle — 2026-01-28T16:50:38Z

Changes are detailed by contribution.
- New keys are in black
- Keys removed in red
- Keys modified (new options, options removed, changes of default values, name changed, change of namelist) in orange
- New namelist in green

NAM_ISBA
- NSAND_LAYER: number of sand layers. Equal to 1 if CISBA = "2-L" or "3-L". Must be equal to 1 or to the number of ground layers if CISBA="DIF".
- NCLAY_LAYER: number of clay layers. Equal to 1 if CISBA = "2-L" or "3-L". Must be equal to 1 or to the number of ground layers if CISBA="DIF".
- CGNDRES : to activate baresoil evaporation resistance options

NAM_MEB_ISBA :
- LMEB_GNDRES is removed (replaced by CMEB_GNDRES)
- CMEB_GNDRES : Activates baresoil evaporation resistance options
- LMEB_TALL_VEG : To use vegetation height as a major variable to calculate maximum snow load on trees and turbulent fluxes.
- LMEB_INT_PLUN : If True, to use the (Lundquist et al., 2021) intercepted snow melt formulation. The snow intercepted by the trees melts faster than using the classical config.
- LMEB_INT_ULUN : If True, to use the snow unloading scheme of (Lundquist et al., 2021). This scheme is globally slowing the solid unloading, which favors snowmelt and sublimation of the intercepted snow as it stays a bit longer on the branches.
- LMEB_INT_USFC : To separate snow unloading from snowfalls in Crocus fresh snow incorporation.

NAM_ISBAn
- CZ0HEAT : roughness length for heat
- XZ0HEAT : factor to calculate Z0H when CZ0HEAT="Z95"

NAM_PREP_ISBA
- XHUG_SURF is removed (replaced by XUNIF_HUG_SOIL)
- XHUG_ROOT is removed (replaced by XUNIF_HUG_SOIL)
- XHUG_DEEP is removed (replaced by XUNIF_HUG_SOIL)
- XHUGI_SURF is removed (replaced by XUNIF_HUGI_SOIL)
- XHUGI_ROOT is removed (replaced by XUNIF_HUGI_SOIL)
- XHUGI_DEEP is removed (replaced by XUNIF_HUGI_SOIL)
- CFILE_HUG_SURF is removed (replaced by CFILE_HUG_SOIL)
- CFILE_HUG_ROOT is removed (replaced by CFILE_HUG_SOIL)
- CFILE_HUG_DEEP is removed (replaced by CFILE_HUG_SOIL)
- XTG_SURF is removed (replaced by XUNIF_TG_SOIL)
- XTG_ROOT is removed (replaced by XUNIF_TG_SOIL)
- XTG_DEEP is removed (replaced by XUNIF_TG_SOIL)
- CFILE_TG_SURF is removed (replaced by CFILE_TG_SOIL)
- CFILE_TG_ROOT is removed (replaced by CFILE_TG_SOIL)
- CFILE_TG_DEEP is removed (replaced by CFILE_TG_SOIL)
- XUNIF_HUG_SOIL : uniform prescribed value for soil wetness index profile
- XUNIF_HUGI_SOIL : uniform prescribed value for ice soil water index profile
- XUNIF_TG_SOIL : uniform prescribed value for soil temperature profile
- CFILE_HUG_SOIL : input file name for Wg, Wgi. The dimension of this key is (NVEGTYPE, NGROUND_LAYER)
- CFILE_TG_SOIL :input file name for TG. The dimension of this key is (NVEGTYPE, NGROUND_LAYER)

NAM_DIAG_FLAKEn
- LSEDIM_PROFIL : flag for sediment diagnostics
- XZSED_PROFILE : depth of output levels (m) in namelist
- LFLKFLUX : flag for heat and radiative diagnostics
- LFLKWATER : flag for water budget P-E diagnostics

NAM_IO_OFFLINE
- CSPECSNOW (removed, replaced by CSPECSNOW)
- LSPECSNOW (before CSPECSNOW)
- LFIX_OUTPUT : logical to force diags output each day at hours that are multiple from the XSTEP_OUTPUT

NAM_SURF_SNOW_CSTS
- XPERCENTAGEPORE_FRZ
- XIMPUR_WET : corresponds to the initial amount of Light-Absorbing Particles (LAP) present in the falling snow (wet deposition) for each impurity type
- XIMPUR_DRY : corresponds to the dry deposition coefficient (always activated) at top of snowpack (in g/m2/s) for black carbon (XIMPUR_DRY(1)), dust (XIMPUR_DRY(2)), and other types of impurities (XIMPUR_DRY(3:5))
- XIMPUR_INIT removed
- XIMPUR_COEF removed
- XPR_A : Adjustable coefficients depending on snow-gun type (Hanzer et al., 2014).
- XPR_B : Adjustable coefficients depending on snow-gun type (Hanzer et al., 2014).
- XPT : Water consumption threshold during base-layer generation production period
- XPP_D1 : Day of beginning of base-layer generation production period. For CROCUS resort only.
- XPP_D2 : Day of end of base-layer generation production period. For CROCUS resort only.
- XPP_D3 : Day of end of reinforcement production period. For CROCUS resort only.
- XPP_H1 : Hour of beginning of base-layer generation production period (in seconds, from midnight). For CROCUS resort only.
- XPP_H2 : Hour of end of base-layer generation production period (in seconds, from midnight). For CROCUS resort only.
- XPP_H3 : Hour of beginning of reinforcement production period (in seconds, from midnight). For CROCUS resort only.
- XPP_H4 : Hour of end of reinforcement production period (in seconds, from midnight). For CROCUS resort only.
- XWT : Wind speed threshold for snowmaking (m/s)
- XPTR : Total (natural+machine-made) snow height threshold during reinforcement production period (m)
- XSCAVEN_COEF : percentage of impurity leaving with percolating water
- XAGELIMPAPPUS : maximum age (days) of snow layer for which wind speed threshold is set to fresh threshold wind speed
- XWINDTHRFRESH : 5m wind speed threshold for transport of freshly fallen (or deposited) snow
- XRHODEPPAPPUS : density (kg.m^-3) of wind blown deposited snow
- XDIAMDEPPAPPUS : optical diameter (m) of wind blown deposited snow
- XSPHDEPPAPPUS : sphericity of wind blown deposited snow
- XLFETCHPAPPUS : constant fetch distance applied to all points for snowpappus blowing snow flux calculation (m)
- XAGELIMPAPPUS2 : maximum age (in days) of snow for using Naaim96 formulation of terminall fall speed in snowpappus
- XDEMAXVFALL : maximum dendricity to have pure young snow fall speed, when option MIXT is chosen for terminal fall speed calculation
- XCROCOEF_FF: to have the possibility to change the coefficient for gust diagnosis from average wind

NAM_ISBA_SNOW
- CSNOWMOB : To choose the way threshold wind speed is computed in SnowPappus when surface snow age is superior to the threshold value XAGELIMPAPPUS
- LSNOWPAPPUS : key to activate SnowPappus option.
- CSNOWPAPPUSERODEPO : determines how the deposition flux is computed.
- CSNOWFPAPPUS : overcomes 'CSNOWDRIFT' to select falling snow microstructure.
- CPAPPUSSUBLI : to choose different parameterizations of blowing snow sublimation rate in SnowPappus
- CSALTPAPPUS : option for saltation transport in SnowPappus
- CLIMVFALL : option to decide what is old or new snow for fall speed calculation
- OPAPPULIMTFLUX : if True, snow transport flux limitation activated.
- OPAPPUDEBUG : if True, triggers snowpappus debug mode.

NAM_DIAG_ISBAn
- LSPECMOD : flag fot snow modis spectral bands diagnostic

NAM_ASSIM
- CASSIM_ISBA : new option 'PF' (for Particle Filter activation in SODA)
- LCROCO : Activation of assimilation for snow scheme Crocus
- CPF_CROCUS : Select the PF (Particle Filter) algo
- NEFF_P : set the target effective sample size for the PF with inflation
- XDLOC_PF : localisation distance (degrees) for the RLOCAL particle filter
- LLOO_PF : activate leave-one-out experiments with the PF (exclude local observations)

NAM_VAR
- XTAUSCF : value for the tau parameter of the depletion curve used to retrieve model SCF from bulk SWE (default=4)
- XCEILSCF : value for the ceil SWE of the depletion curve (default=20mm)

NAM_OBS
- COBS_M : new options possible
- XERROBS_FACTOR_M : magnification factor for obs errors in PF

New developments in SURFEX V9.1.0

Minvielle — 2026-01-28T16:50:14Z

CEN - Crocus

Particle filter in SODA : assimilation of snow depth, optical reflectance, wet snow product (Cluzet et al., 2021, 2022 ; Deschamps-Berger et al., 2022)
Externalization of Crocus with other surface schemes (SVS2, Woolley et al., in review ; FSM2, Mazzotti et al., in review)
Technical optimizations (loops) and cleaning (snow3L_isba), Crocus tests in STRATO
NetCDF4 outputs and compression (optional)
New snow metamorphism B21 (Baron, 2023 ; Lafaysse et al., 2025)
Ice formation when freezing rain (Quéno et al., 2018)
SnowPappus blowing snow transport model for 2D offline simulations (with MPI communications)
(Baron et al., 2024 ; Haddjeri et al., 2024)
Adaptation of snow interception, melt and unloading in MEB for mid-latitudes. Improvement of MEB-Crocus coupling.

SURFACE

MEB : new physics option for ISBA and ISBA-MEB. The addition of an option for both ISBA and ISBA-MEB to include a baresoil resistance for the baresoil evaporation computation. See Marti et al. (2025) for details.
MEB : MEB can be used now for all covers (including low vegetation) except for ROCK, BARESOIL and PERMANENT SNOW patches. Before it was limited to forest patches only.
MEB bugfix : A bugfix of the call to cotwores.F90 from isba_meb.F90 was corrected which caused patch memory to be lost (when using MEB). This redundancy lead to some bugs. This has no impact on results except with MEB-it avoids a bug.
Multi-level initialization for ISBA : it's now possible to initialize temperature and water content for each soil level, and not only SURF/ROOT/DEEP. For exemple, if DIF is used, is now possible to give a value of TG and WG for each of the 14 soil levels. This development leads to a modification of the keys to initialize ISBA. Please refer to the section dedicated to changes of namelist.
Multi-layer texture : possibility to give sand and clay fractions for different soil levels
Ags revision
Landuse/landcover revision
Add of some FLake diagnostics
Optimization
some technical modifications (for MASCOT project) without impact for the user
modifications to prepare possible compilation with cmake without impact for the user
bugfixes