Model Documentation of TM5, with focus on GEMS settings

This report provides a documentation of the global chemistry Transport Model version 5 (TM5), as applied in the GEMS subproject on Global Reactive Gases (GRG) for the period up to 2008. Details are also included on the grid handling (the zoom option), transport modeling and the latest version of the chemical scheme (CBM4).
In addition specific settings for the GEMS project are given, as compared to the standard TM5 version, including a description of procedures related to the coupling to the Integrated Forecast System (IFS) at ECMWF, from the viewpoint of TM5.
Throughout the document information on the specific settings of the reference model runs and sensitivity runs as performed in GEMS-GRG subproject are provided.