General Description: Model External Parameters

see also: dynamics and numerics | initial and boundary conditions | physical parameterizations | code and parallelization | data assimilation
Last updated: September 2011

The parameterization of physical processes, but also the adiabatic model part requires some parameters which are not derived by data assimilation or by interpolation from a driving model. These so-called external parameters are defined in additional data sets.

Additional documentation is available to describe the raw data sets used for the generation of the external parameters.

COSMO external parameters

Below, the external parameters that are currently needed by the COSMO-Model, are listed.

External Parameters for the COSMO-Model
Parameter Short name Unit necessary, if ...
geometrical height HSURF m necessary
geopotential FIS m2s-2 optional (for HSURF)
land cover FR_LAND 1 necessary
standard deviation of subgrid scale orogr. height SSO_STDH m lsso=.TRUE.
anisotropy of topography SSO_GAMMA 1 lsso=.TRUE.
angle betw. principal axis of orogr. and global E SSO_THETA 1 lsso=.TRUE.
mean slope of subgrid scale orography SSO_SIGMA 1 lsso=.TRUE.
surface roughness Z0 m necessary
soil texture SOILTYP 1 necessary
surface emissivity (long wave) EMISS_RAD 1 lemiss=.TRUE.
root depth ROOTDP m necessary
vegetation (plant cover) PLCOV % necessary
ground fraction covered by plants (time of rest) PLCOV_MM 1 necessary
ground fraction covered by plants (vegetation p.) PLCOV_MX 1 necessary
ground fraction covered by evergreen forest FOR_E 1 lforest=.TRUE.
ground fraction covered by deciduous forest FOR_D 1 lforest=.TRUE.
leaf area index (time of rest) LAI_MN 1 necessary
leaf area index (vegetation period) LAI_MX 1 necessary

External parameters for the COSMO-Model can be derived by a preprocessor program for any domain on the globe at (nearly) any required spatial resolution (but not below 2 km). However, this is very time consuming because of the size of the high-resolution global data sets. Within the COSMO group, we thus have some predefined data sets with external parameters on three different domains. The domains are defined with a different rotation, which is specified in the table below. The data sets for these domains are available on the COSMO ftp-server.

Predefined Data Sets with External Parameters for the COSMO-Model
Domain Data Set Grid Size Degrees Meters pollon pollat
Domain d0 cosmo_d0_02800_1605x1605.g1_2007082400 1605x1605 0.025 2800 -170.0 40.0
Domain d1 cosmo_d1_07000_961x769.g1_2009121700 961x769 0.0625 7000 -170.0 32.5
cosmo_d1_14000_481x385.g1_2009121700 481x385 0.125 14000 -170.0 32.5
cosmo_d1_21000_321x257.g1_2009121700 321x257 0.1875 21000 -170.0 32.5
cosmo_d1_28000_241x193.g1_2009121700 241x193 0.25 28000 -170.0 32.5
cosmo_d1_56000_121x113.g1_2009121700 121x113 0.5 56000 -170.0 32.5
Domain d5 cosmo_d5_07000_965x773.g1_2009121700 965x773 0.0625 7000 -170.0 40.0
cosmo_d5_14000_483x387.g1_2009121700 483x387 0.125 14000 -170.0 40.0

The following figures show the areas for the domains d0, d1 and d5 (left to right):

Domain d0 Domain d1 Domain d5

Domain d1 covers Europe and surrounding countries; data sets for this domain are available at 56 km, 28 km, 21 km, 14 km and 7 km grid spacing. They were generated for a rotated grid with its north pole at 32.5o latitude and -170.0o longitude. Such rotation was used at for the first operational implementation of the COSMO-Model (the "LM"). When introducing the COSMO-EU (the bigger domain), DWD switched to a rotated grid with the north pole at 40.0o latitude and -170.0o longitude. Data sets for this rotation are available for Domain d5 and 14 and 7 km resolution. The data set for domain d0 is provided for the resolution of about 2.8 km and has the same rotation as the ones for d5, but the domain is smaller.