Multiphysics¶

Implementation of various physical options for all the main processes
Scientific details: https://www.the-cryosphere.net/11/1173/2017/

Developer name¶

M Lafaysse and B Cluzet

Date of start of development¶

August 2015

Commit number before the development¶

62a95d3e

Current status (in progress, or commit number in cen_dev or cen_release) and expected schedule¶

Stable in branches cen and SURFEX_V9_DEV

Evaluated against SURFEX test database ? yes or no¶

yes

New test added in the database (if yes, describe)¶

yes

Changes in namelist¶

&NAM_ISBA_SNOWn:

CSNOWRAD = B92, T17 option for absorption of solar radiation, default : B92
CSNOWMETAMO = 'C13','F06','T07','S-C','S-F'  option for metamorphism, default : C13
CSNOWFALL = 'V12','S02','A76','P75','NZE' option for falling snow density, default : V12
CSNOWCOMP = 'B92', 'S14', 'T11'  option for compaction, default : B92
CSNOWCOND = 'Y81', 'I02','C11' option for snow thermal conductivity, default : Y81
CSNOWHOLD = 'B92', 'SPK','O04','B02' option for liquid water holding capacity, default B92

Description of options:
CSNOWRAD : radiative transfer scheme in the snowpack
B92 3 band scheme from Brun et al, 1992 with empirical parameterization of ageing in the visible band (default)
T17 2 flow spectral scheme TARTES (Libois et al, 2013) with explicit impact of SSA, impurities, and zenithal angle on spectral reflectances. Increase computing time by a factor of 10. Require a careful setting of impurities deposition.

CSNOWMETAMO
'B92' obsolete option which will be removed in a next version : empirical evolution of dendricity, sphericity and size from Brun et al 1992
'C13' Translation of B92 option in terms of Optical Diameter and Sphericity (default)
'F06' Evolution law of the optical diameter from Flanner and Zender (2006), which fits the model outputs of a snow microstructure model representing the diffusive vapour fluxes among the grains.
'S-C' Experimental evolution law of Optical Diameter from Schleef et al, 2014 for the first 48 hours after snowfall, then C13 option
'S-F' Experimental evolution law of Optical Diameter from Schleef et al, 2014 for the first 48 hours after snowfall, then F06 option
'T07' Experimental evolution law of Optical Diameter from Taillandier et al, 2007

CSNOWFALL : parameterization of falling snow density
'V12' function of air temperature and wind speed following Vionnet et al 2012 from experiments of Pahaut at Col de Porte (default)
'S02' function of air temperature and wind speed following Schmucki et al 2014, law used in the swiss SNOWPACK model (at least since 2002) Take care, the option was called S14 in Lafaysse et al, 2017.
'A76' function of air temperature from Anderson, 1976 (law used in ISBA-ES)
'NZE' constant at 200 kg/m3 for maritime climates (New Zealand)

CSNOWCOMP : parameterization of snow compaction
'B92' visco-elastic model using a viscosity function of density and air temperature from Brun et al, 1992 (default)
'T11' visco-elastic model using a viscosity function of density and air temperature from Teufelsbauer (2011) fitting the data of separate experimental works
'S14' non-linear relationship between settlement, stress and SSA decrease due to metamorphism from Schleef et al. (2014) for the first 48 h after snowfall. Then, B92 option.

CSNOWCOND : parameterization of snow thermal conductivity from snow density
'Y81' Yen et al 1981 (Default) from experimental values
'I02' from ISBA-ES (Boone, 2002; Sun et al., 1999) The law depends not only on density but also on snow temperature and it has a higher conductivity than experimental values to indirectly compensate for the fact that latent heat fluxes due to vapour fluxes are not represented in the model. This is expected to increase vertical heat transfer as temperature increases.

CSNOWHOLD : parameterization of maximum liquid water holding capacity in the bucket parameterization
'B92' fixed maximal percentage of the pores’ volumes from Pahaut 1975
'SPK' parameterization of the swiss SNOWPACK model (Wever et al 2014) fitting the experiments of Coléou and Lesaffre (1998)
'B02' maximal liquid water mass fraction. This parameterization has an opposite behaviour : the higher the density, the higher the maximal volumetric liquid water content.

&NAM_ISBAn:

CSNOWRES = 'DEF', 'RIL', 'M98' option for turbulent fluxes over snow, default : DEF
XCVHEATF default : 0.2 Modify Cv to compensate biases in ground temperature

Other required changes (forcing files, snowtools code or options, VORTEX, ....)¶

Ensemble experiments on MF supercomputers must be run with snowtools_git and vortex with the --escroc option: https://redmine.umr-cnrm.fr/projects/snowtools_git/wiki/Run_a_SURFEX-Crocus_experiment_with_vortex