BROWSER/out_doc80/modd__snow__par_8F90_source.html

 !SFX_LIC Copyright 1994-2014 CNRS, Meteo-France and Universite Paul Sabatier

 !SFX_LIC This is part of the SURFEX software governed by the CeCILL-C licence

 !SFX_LIC version 1. See LICENSE, CeCILL-C_V1-en.txt and CeCILL-C_V1-fr.txt

 !SFX_LIC for details. version 1.

 !     ######################

       MODULE modd_snow_par

 !     ######################

 !

 !!****  *MODD_SNOW_PAR* - declaration of parameters related

 !!                          to the snow parameterization

 !!

 !!    PURPOSE

 !!    -------

 !       The purpose of this declarative module is to specify  the

 !     parameters related to the surface parameterization of snow.

 !

 !!

 !!**  IMPLICIT ARGUMENTS

 !!    ------------------

 !!      None

 !!

 !!    REFERENCE

 !!    ---------

 !!

 !!

 !!    AUTHOR

 !!    ------

 !!      V. Masson   *Meteo France*

 !!

 !!    MODIFICATIONS

 !!    -------------

 !!      Original       01/2004

 !! P. Samuelsson  10/2014   MEB complements

 !-------------------------------------------------------------------------------

 !

 !*       0.   DECLARATIONS

 !             ------------

 !

 IMPLICIT NONE

 !

 !--------------------------------------------------------------------------------

 ! Snow on the ground: Given in ini_surf_csts and/or in NAM_SURF_CSTS

 !--------------------------------------------------------------------------------

 !

 ! Snow emissivity:

 !

 REAL, SAVE       :: XEMISSN

 !

 ! Minimum and maximum values of the albedo of snow:

 !

 REAL, SAVE       :: XANSMIN

 REAL, SAVE       :: XANSMAX

 !

 ! Minimum and maximum values of the albedo of permanet snow/ice:

 !

 REAL, SAVE       :: XAGLAMIN

 REAL, SAVE       :: XAGLAMAX

 !

 ! Use recommended settings for snow albedo (FALSE = ISBA default)

 !

 LOGICAL,SAVE     :: LMEBREC

 !

 ! Fraction of maximum value of the albedo of snow that is reached for melting

 ! snow

 !

 REAL, SAVE       :: XANSFRACMEL

 !

 ! Threeshold temperature above which the snow albedo starts to decrease

 !

 REAL, SAVE       :: XTEMPANS

 !

 ! Minimum value of the albedo of snow reached under canopy vegetation:

 !

 REAL, SAVE       :: XANSMINMEB

 !

 ! Prescribed ice albedo in 3 spectral bands for glacier simulation with CROCUS scheme.

 REAL, SAVE       :: XALBICE1,XALBICE2,XALBICE3

 !


 ! Density threshold for ice detection in CROCUS scheme.

 REAL, SAVE       :: XRHOTHRESHOLD_ICE


 !for ageing effects

 REAL, SAVE      :: XVAGING_NOGLACIER, XVAGING_GLACIER


 ! percentage of the total pore volume to compute the max liquid water holding capacity

 REAL, SAVE      :: XPERCENTAGEPORE


 ! Height (m) of aged snow in glacier case (allows Pn=1)

 !

 REAL, SAVE       :: XHGLA

 !

 ! Coefficient for calculation of snow fraction over vegetation

 !

 REAL, SAVE       :: XWSNV

 !

 ! Roughness length of pure snow surface (m)

 !

 REAL, SAVE       :: XZ0SN

 !

 ! Roughness length for heat of pure snow surface (m)

 !

 REAL, SAVE       :: XZ0HSN

 !

 ! Roughness length ratio between ice and snow

 REAL, SAVE       :: XZ0ICEZ0SNOW

 !

 ! Snow Melt timescale with D95 (s): needed to prevent time step

 ! dependence of melt when snow fraction < unity.

 !

 REAL, SAVE       :: XTAU_SMELT

 !

 !--------------------------------------------------------------------------------

 ! Snow on the ground: PARAMETER

 !--------------------------------------------------------------------------------

 !

 ! Critical value of the equivalent water content

 ! of the snow reservoir for snow fractional coverage and albedo computations

 !

 REAL, PARAMETER       :: XWCRN      = 10.0   ! (kg m-2) Veg (default value)

 REAL, PARAMETER       :: XWCRN_EXPL =  1.0   ! (kg m-2) Veg explicit

 REAL, PARAMETER       :: XWCRN_ROOF =  1.0   ! (kg m-2)  Roofs

 REAL, PARAMETER       :: XWCRN_ROAD =  1.0   ! (kg m-2)  Roads

 REAL, PARAMETER       :: XWCRN_VEG  =  1.0   ! (kg m-2)  Urban veg

 !

 ! Critical value of the total snow depth for ground snow fractional coverage

 !

 REAL, PARAMETER       :: XDCRN_EXPL = 0.01  ! (m) Veg explicit

 !

 ! Critical value of snow emissivity

 !

 REAL, PARAMETER       :: XEMCRIN = 0.98

 !

 ! Minimum and maximum values of the albedo of snow:

 !

 REAL, PARAMETER       :: XANSMIN_ROOF = 0.30 ! (-)   Roofs

 REAL, PARAMETER       :: XANSMIN_ROAD = 0.15 ! (-)   Roads

 !

 REAL, PARAMETER       :: XANSMAX_ROOF = 0.85 ! (-)   Roofs

 REAL, PARAMETER       :: XANSMAX_ROAD = 0.85 ! (-)   Roads

 !

 ! Snow aging coefficients (albedo and Force-Restore density):

 !

 REAL, PARAMETER       :: XANS_TODRY    = 0.008     ! (-) Veg (default value)

 REAL, PARAMETER       :: XANS_TODRY_ROOF = 0.008   ! (-)  Roofs

 REAL, PARAMETER       :: XANS_TODRY_ROAD = 0.008   ! (-)  Roads

 REAL, PARAMETER       :: XANS_TODRY_MEB  = 0.016   ! (-) Surface under canopy vegetation

 !

 REAL, PARAMETER       :: XANS_T        = 0.240     ! (-) Veg (default value)

 REAL, PARAMETER       :: XANS_T_ROOF     = 0.174   ! (-)  Roofs

 REAL, PARAMETER       :: XANS_T_ROAD     = 0.174   ! (-)  Roads (alley simul)

 REAL, PARAMETER       :: XANS_T_MEB    = 0.480     ! (-) Surface under canopy vegetation

 !

 ! Minimum and maximum values of the density of snow

 ! for Force-Restore snow option

 !

 REAL, PARAMETER       :: XRHOSMIN = 100.       ! (kg m-3)   Veg (Default value)

 REAL, PARAMETER       :: XRHOSMIN_ROOF = 100.  ! (kg m-3)   Roofs

 REAL, PARAMETER       :: XRHOSMIN_ROAD = 100.  ! (kg m-3)   Roads

 !

 REAL, PARAMETER       :: XRHOSMAX = 300.       ! (kg m-3)   Veg (Default value)

 REAL, PARAMETER       :: XRHOSMAX_ROOF = 300.  ! (kg m-3)   Roofs

 REAL, PARAMETER       :: XRHOSMAX_ROAD = 350.  ! (kg m-3)   Roads

 !

 ! Minimum and maximum values of the density of snow

 ! for ISBA-ES snow option

 !

 REAL, PARAMETER       :: XRHOSMIN_ES =  50.  ! (kg m-3)

 REAL, PARAMETER       :: XRHOSMAX_ES = 750.  ! (kg m-3)

 !

 ! ISBA-ES Critical snow depth at which snow grid thicknesses constant

 !

 REAL, PARAMETER       :: XSNOWCRITD = 0.03  ! (m)

 !

 ! ISBA-ES Minimum total snow depth for thermal calculations.

 ! Used to prevent numerical problems as snow becomes vanishingly thin.

 !

 REAL, PARAMETER      :: XSNOWDMIN = 0.000001  ! (m)

 !

 ! Maximum Richardson number limit for very stable conditions using the ISBA-ES 'RIL' option

 !

 REAL, PARAMETER       :: X_RI_MAX = 0.20

 !

 ! ISBA-ES Maximum snow liquid water holding capacity (fraction by mass) parameters:

 !

 REAL, PARAMETER       :: XWSNOWHOLDMAX2   = 0.10  ! (-)

 REAL, PARAMETER       :: XWSNOWHOLDMAX1   = 0.03  ! (-)

 REAL, PARAMETER       :: XSNOWRHOHOLD     = 200.0 ! (kg/m3)

 !

 ! ISBA-ES arameters for grain size computation :

 !

 REAL, PARAMETER       :: XSNOW_AGRAIN = 1.6e-4   ! (m)

 REAL, PARAMETER       :: XSNOW_BGRAIN = 1.1e-13  ! (m13/kg4)

 REAL, PARAMETER       :: XSNOW_CGRAIN = 0.5e-4   ! (m)

 REAL, PARAMETER       :: XDSGRAIN_MAX = 2.796e-3 ! m

 !

 !--------------------------------------------------------------------------------

 ! Calibration coefficients for CROCUS and ES albedo computation

 !--------------------------------------------------------------------------------

 !

 REAL, PARAMETER :: XD1 = 1., XD2 = 3., XD3 = 4., XX = 99., &

                    XVALB2 = .96, XVALB3 = 1.58, XVALB4 = .92, XVALB5 = .90, &

                    XVALB6 = 15.4, XVALB7 = 346.3, XVALB8 = 32.31, XVALB9 = .88, &

                    XVALB10 = .200, XVALB11 = .6, XVDIOP1 = 2.3E-3, XVRPRE1 = .5, &

                    XVRPRE2=1.5

 !

 ! for ageing effects:

 REAL, PARAMETER :: XVPRES1 = 87000.

 !

 ! spectral bands

 !

 INTEGER, PARAMETER :: NSPEC_BAND_SNOW = 3

 !

 ! for spectral distribution and thickness effects

 REAL, PARAMETER :: XVSPEC1 = .71, XVSPEC2 = .21, XVSPEC3 = .08

 !

 ! for thickness effects

 REAL, PARAMETER :: XVW1 = .80, XVW2 = .20 , XVD1 = .02, XVD2 = .01

 !

 !--------------------------------------------------------------------------------

 ! calibration coefficients for exctinction computation

 REAL, PARAMETER :: XVBETA1 = 1.92E-3, XVBETA2 = 40., XVBETA3 = 1.098E-2, &

                    XVBETA4 = 100.,  XVBETA5 = 2000.

 !

 ! ISBA-ES minimum cosinus of zenithal angle

 REAL, PARAMETER :: XMINCOSZEN = 0.01

 !

 !--------------------------------------------------------------------------------

 ! ISBA-ES Thermal conductivity coefficients from Anderson (1976):

 ! see Boone, Meteo-France/CNRM Note de Centre No. 70 (2002)

 !

 REAL, PARAMETER :: XSNOWTHRMCOND1 = 0.02    ! [W/(m K)]

 REAL, PARAMETER :: XSNOWTHRMCOND2 = 2.5E-6  ! [W m5/(kg2 K)]

 !

 ! ISBA-ES Thermal conductivity: Implicit vapor diffn effects

 ! (sig only for new snow OR high altitudes)

 ! from Sun et al. (1999): based on data from Jordan (1991)

 ! see Boone, Meteo-France/CNRM Note de Centre No. 70 (2002)

 !

 REAL, PARAMETER :: XSNOWTHRMCOND_AVAP = -0.06023 ! [W/(m K)]

 REAL, PARAMETER :: XSNOWTHRMCOND_BVAP = -2.5425  ! (W/m)

 REAL, PARAMETER :: XSNOWTHRMCOND_CVAP = -289.99  ! (K)

 !

 ! Crocus thermal conducitivity coefficient from Yen (1981)

 REAL, PARAMETER :: XVRKZ6 = 1.88

 !

 !--------------------------------------------------------------------------------

 ! ISBA-ES CROCUS (Pahaut 1976): snowfall density coefficients:

 !

 REAL, PARAMETER :: XSNOWFALL_A_SN = 109.0  ! kg/m3

 REAL, PARAMETER :: XSNOWFALL_B_SN =   6.0  ! kg/(m3 K)

 REAL, PARAMETER :: XSNOWFALL_C_SN =  26.0  ! kg/(m7/2 s1/2)

 !

 ! Coefficients for the optimal vertical grid calculation

 REAL, PARAMETER :: XDZ1 = 0.01

 REAL, PARAMETER :: XDZ2 = 0.0125

 REAL, PARAMETER :: XDZ3 = 0.015

 REAL, PARAMETER :: XDZ3_BIS = 0.03

 REAL, PARAMETER :: XDZ4 = 0.04

 REAL, PARAMETER :: XDZ5 = 0.05

 REAL, PARAMETER :: XDZ_BASE = 0.02

 REAL, PARAMETER :: XDZ_INTERNAL = 0.07

 REAL, PARAMETER :: XSCALE_CM = 100.

 REAL,DIMENSION(5), PARAMETER :: XDZMAX_INTERNAL = (/0.5,1.,2.,4.,10./)

 REAL, PARAMETER :: XDZMIN_TOP_EXTREM = 0.0001

 !

 ! Below this threshold of snowfall, new snowfall are aggregated with surface layer to avoid numerical problems

 ! (0.03 mm/h)

 REAL,PARAMETER :: XSNOWFALL_THRESHOLD = 0.0333/3600.


 ! The ratio between a new surface layer thickness and the second layer surface thickness is limited to 1/10

 REAL,PARAMETER :: XRATIO_NEWLAYER = 0.1


 ! Coefficients for cases with very thick snowpacks

 REAL, PARAMETER :: XDEPTH_THRESHOLD1 = 3.

 REAL, PARAMETER :: XDEPTH_THRESHOLD2 = 20.

 REAL, PARAMETER :: XDEPTH_SURFACE = 3.

 !

 ! Coefficients for computing the difference in 2 snow layer characteristics

 REAL, PARAMETER :: XDIFF_1 = 20.

 REAL, PARAMETER :: XDIFF_MAX = 200.

 REAL, PARAMETER :: XSCALE_DIFF = 25.

 !

 ! Coeefficients for snow layer splitting

 REAL, PARAMETER :: XDZMIN_TOP = 0.01

 REAL, PARAMETER :: XDZMIN_TOP_BIS = 0.005

 REAL, PARAMETER :: XDZMIN_BOT = 0.02

 REAL, PARAMETER :: XSPLIT_COEF = 8.

 !

 ! Coeefficients for snow layer agregation

 REAL, PARAMETER :: XAGREG_COEF_1 = 5.

 REAL, PARAMETER :: XAGREG_COEF_2 = 4.5

 !

 !--------------------------------------------------------------------------------

 !

 ! Calibration coefficients

 REAL, PARAMETER :: XVTIME = 48*3600. ! characteristic time for

 !compaction and metamorphism by wind drift

 !

 REAL, PARAMETER :: XVROMAX = 350. !  maximum density for

 ! drift compaction     UNIT : kg m-3

 REAL, PARAMETER :: XVROMIN = 50.  !  minimum density for

 ! mobility computation UNIT : kg m-3

 REAL, PARAMETER :: XVMOB1 = 0.295  !  coefficient for computing

 ! the mobility index

 REAL, PARAMETER :: XVMOB2 = 0.833  !  coefficient for computing

 ! the mobility index

 REAL, PARAMETER :: XVMOB3 = 0.583  !  coefficient for computing

 ! the mobility index

 REAL, PARAMETER :: XVMOB4 = -0.0583 !  coefficient for computing

 ! the mobility index

 REAL, PARAMETER :: XVDRIFT1 = 2.868 !  coefficient for computing

 ! the drift index

 REAL, PARAMETER :: XVDRIFT2 = 0.085 !  coefficient for computing

 ! the drift index

 REAL, PARAMETER :: XVDRIFT3 = 3.25  !  coefficient for computing

 ! the drift index

 REAL, PARAMETER :: XVSIZEMIN = 3.E-4 !  minimum size decrease

 ! by drift  UNIT = m

 !

 ! modif_EB pour sublim

 ! a pour but de tenir compte du fait que le vent moyen est > rafales

 ! on en tient compte egalement pour diminuer la duree de l'effet

 REAL, PARAMETER :: XCOEF_FF = 1.25 ! coefficient for gust diagnosis from average wind

 REAL, PARAMETER :: XCOEF_EFFECT = 1.0 ! coefficient for impact on density du drift

 REAL, PARAMETER :: XQS_REF = 2.E-5 ! valeur de reference de ZQS pour effet neige

 !

 !--------------------------------------------------------------------------------

 !

 ! ISBA-ES snow grid parameters

 !

 REAL, PARAMETER, DIMENSION(3)     :: XSGCOEF1  = (/0.25, 0.50, 0.25/)

 REAL, PARAMETER, DIMENSION(2)     :: XSGCOEF2  = (/0.05, 0.34/)

 REAL, PARAMETER, DIMENSION(10)    :: XSGCOEF3  = (/0.025, 0.033, 0.043, &

                                      0.055, 0.071, 0.091, 0.117, 0.150, &

                                      0.193, 0.247/)

 !

 ! Minimum total snow depth at which surface layer thickness is constant:

 !

 REAL, PARAMETER                   :: XSNOWTRANS = 0.20                ! (m)

 REAL, PARAMETER                   :: XSNOWTRANS1 = 0.40                ! (m)

 REAL, PARAMETER                   :: XSNOWTRANS2 = 0.6061                ! (m)

 REAL, PARAMETER                   :: XSNOWTRANS3 = 0.7143               ! (m)

 REAL, PARAMETER                   :: XSNOWTRANS4 = 0.9259                ! (m)

 REAL, PARAMETER                   :: XSNOWTRANS5 = 1.4493                ! (m)

 !

 !------------------------------------------------------------------------------

 !

 END MODULE modd_snow_par


modd_snow_par
Definition: modd_snow_par.F90:6