The concept of surface layer func-tions is adopted to avoid an excessive number of meshes near the ground due to very steep parameter gradients, occurring at the region.
surface pressure, orography, surface temperature and relative moisture contents, deep soil temperature and moisture contents, snow cover, albedo, emissivity, land sea mask, proportion of vegetation, roughness length, standard deviation, anisotropy and orientation of sub-grid scale orography.
wind, temperature, specific humidity
surface pressure, orography, surface temperature and relative moisure contents, snow cover, albedo, emissivity, land sea mask, proportion of vegetation, roughness lenght, standard deviation, anisotropy and orientation of sub-grid scale orography
wind, temperature, specyfic humidity
Land surface scheme De Ridder and Schayes (1997)
Rigid lid, Rayleigh damping.
Relaxation to large-scale fields (nesting)
Relaxation to large-scale fields (nesting)
Surface model used
No vertical motion condition at the top
Relaxation condition
Relaxation condition
Digital-Filter initialization of unbalanced initial states (Lynch et al., 1997)
with options for adiabatic and diabatic initialization.
Options for rigid lid condition and Rayleigh damping layer.
1-way nesting by Davies-type lateral boundary formulation.
Data from several coarse-grid models can be processed (GME, IFS, LM). Option for periodic boundary conditions.
Friction boundary conditions boundary conditions for horiz. vel., temp. and water substances, non-penetrative for grid-scale mass fluxes, free slip for u and v, extrapolated boundary cond. for pressure disturbance.
Rayleigh damping layer,non-penetrative boundary conditions = rigid lid with free-slip condition for horiz. vel., temp. and water substances.
Interpolation from ECMWF global model IFS, with relaxation boundary condition after Davies(1976) for all prognostic variables except vert. velocity
Friction boundary conditions boundary conditions for horiz. vel., temp. and water substances, non-penetrative for grid-scale mass fluxes, free slip for u and v, extrapolated boundary cond. for pressure disturbance.
Rayleigh damping layer,non-penetrative boundary conditions = rigid lid with free-slip condition for horiz. vel., temp. and water substances.
Interpolation from ECMWF global model IFS, with relaxation boundary condition after Davies(1976) for all prognostic variables except vert. velocity.
Digital-Filter initialization of unbalanced initial states (Lynch et al., 1997)
with options for adiabatic and diabatic initialization.
Options for rigid lid condition and Rayleigh damping layer.
1-way nesting by Davies-type lateral boundary formulation.
Data from several coarse-grid models can be processed (GME, IFS, LM). Option for periodic boundary conditions.
Friction boundary conditions for constant-flux layer with surface budget
Free slip (vanishing vertical velocity and gradients)
Relaxation conditions forcing adaption to profiles of outer-nest model or to reanalysis data of global model GME (within a zone of few cells at each lateral boundary)
Same as lateral inflow
Surface analysis
Climate files
u,v,t,q,ps
u,v,t,q,ps
land-sea mask, roughness length, sea surface temperature, land surface temperature, deep soil temperature, soil wetness, snow fraction on the ground, sea ice, surface albedo
no-slip, energy-budget, land-use parameters
rigid lid with sponge layer
specified values from synoptic background fields
Orlanski-type radiating b.c.
SST from analysis fixed during model integration
model top at 10hPa
none (global model)
none (global model)
prescibed SST
ECMWF boundary condition files
ECMWF boundary condition files
friction boundary conditions for horiz. vel., temp. and water substances, non-penetrative for grid-scale mass fluxes, extrapolated boundary cond. for pressure disturbance.
Rayleigh damping layer,non-penetrative boundary conditions = rigid lid with free-slip condition for horiz. vel., temp. and water substances.
interpolation from DWD's global model GME,with relaxation boundary condition after Davies(1976) for all prognostic variables.
friction boundary conditions boundary conditions for horiz. vel., temp. and water substances, non-penetrative for grid-scale mass fluxes, free slip for u and v, extrapolated boundary cond. for pressure disturbance.
Rayleigh damping layer,non-penetrative boundary conditions = rigid lid with free-slip condition for horiz. vel., temp. and water substances.
interpolation from DWD's global model GME,with relaxation boundary condition after Davies(1976) for all prognostic variables except vert. velocity.
see LME model documentation
see LME model documentation
see LME model documentation
see LME model documentation
Several options (constant values, surface energy budgets, constant fluxes)
rigid lid, damping layers; towards forcing data
Towards forcing data (relaxation area) or modified radiation boundary condition
Towards forcing data (relaxation area) or modified radiation boundary condition
various geophysical and climatological fields (land-sea mask, roughness length, sea surface temperature, land surface temperature, deep soil temperature, soil wetness, snow fraction on the ground, sea ice, surface albedo)
rigid lid with no vertical motion at the model top
time varying meteorological fields coming either from global model (GEM-AQ) results or from objective anaysis
Soil model
The lower boundary coincides with the ground (or, more precisely, a height above ground corresponding to its aerodynamic roughness). For the nonhydrostatic part of the mesoscale pressure perturbation, inhomogeneous Neumann conditions are imposed. All othe
Neumann for the horizontal velocity components and the potential temperature. To ensure non-reflectivity, a radiative condition is used for the hydrostatic part of the mesoscale pressure perturbation. For the nonhydrostatic part of the mesoscale pressure
Radiation conditions for u,v,w, potential temperature and pressure. For the nonhydrostatic mesoscale pressure perturbation, homogeneous Neumann conditions are used.
see above
The lower boundary coincides with the ground. For mesoscale pressure perturbation, inhomogeneous Neumann consitions are imposed. All other consitions at the lower boundary follow the onin-Obukhov similarity theory.
Neumann boundary conditions are imposed for horizontal velocity components and potential temperature. For the mesoscale pressure perturbation homogeneous staggered Dirichlet conditions are impose.
Homogeneous Neumann boundary conditions.
Homogeneous Neumann boundary conditions.
surface exchange parameterization (two layer model; cf. above)
- prescribed large scale flow
- optional absorbing layer
- standard Dirichlet
- optional absorbing layer
- standard Neuman
- optional absorbing layer
Several options (constant values, surface energy budgets, constant fluxes)
rigid lid, damping layers; towards forcing data
Towards forcing data (relaxation area) or modified radiation boundary condition
Towards forcing data (relaxation area) or modified radiation boundary condition
constant values or budget equation
rigid with damping layers
The LOWBDY_DOMAINx file provides sea-surface temperature, substrate temperature, and optionally snow cover and sea-ice. The switch ISSTVAR allows multiple times in this file (created by INTERPF) to be read in as the model runs, which is the method of updating these fields in long-term simulations.
- No upper boundary condition -
Rigid lid with no vertical motion at the model top. This may be preferable for very coarse mesh simulations (50 km or more grids).
1. Upper radiative condition -
Top vertical motion calculated to reduce reflection of energy from the model top preventing some spurious noise or energy build-up over topography. This is recommended for grid-lengths below 50 km. It works better for hydrostatic gravity wave scales, rather than inertial or nonhydrostatic scales.
1 - Fixed
2 - Time-dependent/Nest
Outer two rows and columns have specified values of all predicted fields. Recommended for nests where time-dependent values are supplied by the parent domain. Not recommended for coarse mesh where only one outer row and column would be specified.
3 - Relaxation/inflow-outflow
Outer row and column is specified by time-dependent value, next four points are relaxed towards the boundary values with a relaxation constant that decreases linearly away from the boundary.
several options are available: fixed; Sponge Boundary Conditions;Nudging Boundary Conditions
The LOWBDY_DOMAINx file provides sea-surface temperature, substrate temperature, and optionally snow cover and sea-ice. The switch ISSTVAR allows multiple times in this file (created by INTERPF) to be read in as the model runs, which is the method of updating these fields in long-term simulations.
- No upper boundary condition -
Rigid lid with no vertical motion at the model top. This may be preferable for very coarse mesh simulations (50 km or more grids).
1. Upper radiative condition -
Top vertical motion calculated to reduce reflection of energy from the model top preventing some spurious noise or energy build-up over topography. This is recommended for grid-lengths below 50 km. It works better for hydrostatic gravity wave scales, rather than inertial or nonhydrostatic scales.
1 - Fixed
2 - Time-dependent/Nest
Outer two rows and columns have specified values of all predicted fields. Recommended for nests where time-dependent values are supplied by the parent domain. Not recommended for coarse mesh where only one outer row and column would be specified.
3 - Relaxation/inflow-outflow
Outer row and column is specified by time-dependent value, next four points are relaxed towards the boundary values with a relaxation constant that decreases linearly away from the boundary.
Many options are available: single slab with fixed-temperature substrate or five layer soil model base on the 'force-restore' method developed by Blackadar;Pleim-Xiu Land-Surface Model;Noah Land-Surface Model
Radiative boundary conditions
several options are available: fixed; Sponge Boundary Conditions;Nudging Boundary Conditions
several options are available: fixed; Sponge Boundary Conditions;Nudging Boundary Conditions
4 options avalaible. AT GKSS NOAH land surface model with 4 layers is used.
radiative boundary conditions
time dependent values in one outer row and column for the coarse mesh. Two outer rows and columns are used for nests. Several outer meteorology data sets can be used for lateral boundary conditions. At GKSS, ERA40 data is used.
Depends on variables prescribed at the boundaries. Variables which are not specified by the outer meteorology fields are zero on inflow and zero grdaient on outflow.
Given by the externalized surface model
Rigid
For the coarser model, open boundary conditions with radiative properties from the LS coupling model.
For the inner models, interpolation from the coarser grid.
Radiative open boundary conditions
no condition or weak sponge
Davies, 1976
Davies, 1976
SVAT model (LEAF-2)
Rayleigh friction absorbing layer.
Klemp and Wilhelmson scheme.
Klemp and Wilhelmson
no-slip condition (u=v=0) is specified for the horizontal velocities.
For the vertical velocity, the lower boundary condition is always w*=0. The temperature at the ground surface is predicted from an energy balance through a Newton-Raphson iterative technique.
the upper boundary is an isentropic surface with no horizontal velocity perturbation from the basic state.
zero-gradient lateral boundary conditions are imposed on all prognostic variables
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The soil and vegetation parameterisations are based on those from Kowalczyk et al. (1991).
At the model top boundary, all
variables are set at their synoptic values.
One-way nested lateral boundary conditions are used for the prognostic equations.
No slip or free slip in dynamics, no slip via PBL.
w=0
Davies relaxation
Davies relaxation
SST's
mass coordinate
Analysis data from operational centers, or 1-way nesting, also forecasts from operational centers