NAM_DYNn

It contains the specific dynamic parameters for the model n. They are included in the module MODD_DYNn.

NAM_DYNn content

Fortran name

Fortran type

Default value

XTSTEP

REAL

60.0

CPRESOPT

CHARACTER(LEN=4)

‘CRESI’

NITR

INTEGER

4

LRES

LOGICAL

.FALSE.

XRES

REAL

1.E-07

LITRADJ

LOGICAL

.TRUE.

XRELAX

REAL

1.0

LHORELAX_UVWTH

LOGICAL

.FALSE.

LHORELAX_RV

LOGICAL

.FALSE.

LHORELAX_RC

LOGICAL

.FALSE.

LHORELAX_RR

LOGICAL

.FALSE.

LHORELAX_RI

LOGICAL

.FALSE.

LHORELAX_RS

LOGICAL

.FALSE.

LHORELAX_RG

LOGICAL

.FALSE.

LHORELAX_RH

LOGICAL

.FALSE.

LHORELAX_TKE

LOGICAL

.FALSE.

LHORELAX_SV

array LOGICAL

.FALSE.

LHORELAX_SVC2R2

LOGICAL

.FALSE.

LHORELAX_SVLIMA

LOGICAL

.FALSE.

LHORELAX_SVLG

LOGICAL

.FALSE.

LHORELAX_SVCHEM

LOGICAL

.FALSE.

LHORELAX_SVDST

LOGICAL

.FALSE.

LHORELAX_SVPP

LOGICAL

.FALSE.

LHORELAX_SVAER

LOGICAL

.FALSE.

LHORELAX_SVFIRE

LOGICAL

.FALSE.

LVE_RELAX

LOGICAL

.FALSE.

LVE_RELAX_GRD

LOGICAL

.FALSE.

NRIMX

INTEGER

1

NRIMY

INTEGER

1

XRIMKMAX

REAL

1 / (100*60.)

XT4DIFU

REAL

1800.0

XT4DIFTH

REAL

1800.0

XT4DIFSV

REAL

1800.0

LOCEAN

LOGICAL

.FALSE.

  • XTSTEP : Time step in seconds. If the model is not the DAD model, XTSTEP is not taken into account but NDTRATIO in NAM_NESTING.

  • CPRESOPT : Pressure solver option. 3 choices are implemented in Meso-NH for the moment (see the Scientific documentation for more details) :

    • ‘RICHA’ Richardson method preconditionned by the flat cartesian operator

    • ‘CGRAD’ Generalized pre-conditioned gradient for non-symmetric problems with the same preconditioner

    • ‘CRESI’ Conjugate Residual method

    • ‘ZRESI’ Parallelized version of Conjugate Residual method

Note

If the problem is flat and cartesian, then the resolution becomes exact and no iteration is performed.

  • NITR : Number of iterations for the pressure solver. The value of this parameter depends on the maximum slope of the orography in the model.

Note

NITR cannot be set in a restarted simulation (CCONF=’RESTA’) because the value of the previous timestep is used to ensure reproducibility between restarted and non-restarted runs.

  • LRES : flag to change the residual divergence limit

  • XRES : Value of the residual divergence limit

  • LITRADJ : Logical to adjust the number of iterations for the pressure solver according to the range of the residual divergence.

  • XRELAX : Relaxation coefficient in the Richardson method (CPRESOPT=’RICHA’). This value can be less than 1 only for very steep orography, in general, the optimal value is equal to 1.

  • LHORELAX_UVWTH : Flag for the horizontal relaxation applied on the outermost verticals of the model for U,V,W TH variables.

    • .TRUE. The horizontal relaxation is applied

    • .FALSE. The horizontal relaxation is not applied

Note

  • LHORELAX_RV, LHORELAX_RC, LHORELAX_RR, LHORELAX_RI, LHORELAX_RS, LHORELAX_RG, LHORELAX_RH, LHORELAX_TKE, LHORELAX_SV, LHORELAX_SVCHEM, LHORELAX_SVC2R2, LHORELAX_SVLIMA, LHOREAX_SVLG, LHORELAX_SVDST, LHORELAX_SVPP, LHORELAX_SVAER, LHORELAX_SVELEC, LHORELAX_SVSNW, LHORELAX_SVFIRE : same as LHORELAX_UVWTH

  • It is safer to set all the LHORELAX values rather than use their default values which can be modified by the descriptive (.des) file.

  • LVE_RELAX : Flag for the vertical relaxation applied to the outermost verticals of the model.

    • .TRUE. The vertical relaxation is applied

    • .FALSE. The vertical relaxation is not applied

  • LVE_RELAX_GRD : Flag for the vertical relaxation applied to the lowest verticals of the model.

    • .TRUE. The vertical relaxation is applied

    • .FALSE. The vertical relaxation is not applied

  • NRIMX : number of points in the lateral relaxation in the x axis.

  • NRIMY : number of points in the lateral relaxation in the Y axis.

  • XRIMKMAX : maximum value (in \(s^{-1}\)) of the relaxation coefficient for the lateral relaxation area. This value is applied to all the outermost verticals of the domain if LHO_RELAX.

  • XT4DIFU : characteristic time (e-folding time) of the fourth order numerical diffusion for momentum (in seconds). Associated to LNUMDIFU in NAM_DYN.

  • XT4DIFTH : characteristic time (e-folding time) of the numerical diffusion of fourth order for meteorological variables (in seconds). Associated to LNUMDIFTH in NAM_DYN.

  • XT4DIFSV : characteristic time (e-folding time) of the numerical diffusion of fourth order for scalar variables (in seconds). Associated to LNUMDIFSV in NAM_DYN.

  • LOCEAN : flag to activate the Ocean version of Meso-NH. Pronostic variables are: Current (U and V), Vertical velocity (W), Temperature (TH), Subgrid Turbulent Kinetic Energy (TKE). Salinity (RV) can be activated with LUSERV=T. The Z-axis is directed upward (as in the atmosphere version), i.e. top of model domain corresponds to the sea surface.