The main tool for climate  modelling at DLR is the General Circulation Model (GCM) ECHAM4, which was developed  at the Meteorological Institute of the University of Hamburg in cooperation with the Max-Planck-Institute for Meteorology, Hamburg. A description of the operational version 4 of ECHAM can be found here.

At DLR, special versions of ECHAM are used which are:
 

• ECHAM4.L39(DLR)

A version of ECHAM4 with enhanced vertical resolution (39 instead of 19 layers from the surface to 10 hPa).
 
• ECHAM4.L39(DLR)/CHEM

This is ECHAM4.L39(DLR) coupled to the module CHEM which treats the main aspects of atmospheric chemistry.
 
• ECHAM4/MLO

ECHAM4 coupled to a model of the mixed layer ocean.
 
• ECHAM4/ATTILA

ECHAM4 including the Lagrangian transport scheme ATTILA which calculates on-line trajectories and can be used to transport passive tracers in a Lagrangian manner.