The COSMO-CLM needs initial and boundary data provided by a model covering a larger area than the simulation area of your chosen COSMO-CLM domain. Possible data can be taken eg. from
- Reanalysis
- GCM
- RCM
- COSMO-CLM (in case of double nesting)
A number of meteorological variables are needed as initial and boundary data.
These data 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 in different output formats and have to be converted to a standard that INT2LM can read (so called "INT2LM ready" data).
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 (login necessary).