Initial & Boundary Data
COSMO-CLM needs initial and boundary data covering a larger area than the domain which should be simulated. The data can be taken e.g. from
- Reanalysis
- Global Climate Models (GCMs)
- Regional Climate Models (RCMs)
- COSMO-CLM (in case of double nesting)
A number of meteorological variables are needed as initial and boundary data. These variables are the input for the interpolation programm INT2LM which transfers the data onto the COSMO-CLM grid. However, these data can not be used right away (except the output of a coarser COSMO-CLM simulation), because they are usually provided in different formats and have to be converted to a standard that INT2LM can read (so called "INT2LM ready" data). The preparation of the data for INT2LM is done via so-called converter programs. A list of GCMs for which converter programs already exist is availble here.
Forcing data have to be netCDF (standard CF-1.0 formatted) or GRIB format. Minimal resolution in time recommended is 6 hours. Following Denis et al. (2003) a factor of 12 in horizontal resolution between the forcing data and regional simulation is the maximum. Further information on requirements are given in the core documentation part5.
Several already converted ("INT2LM ready") data sets (e.g. NCEP, ERA and COSMO-CLM-data) are available at the DKRZ. For a complete list and how to access the data please visit https://redc.clm-community.eu/projects/cclmdkrz/wiki/INT2LM_input_data_sets.