The GFZ has been working in the ATC atmosphere program since 2010.  

ATC stands for “Atmospheric Temperature Changes and their Drivers” and is concerned with the analysis of atmospheric temperature changes and their causes. 

ATC is part of APARC (Atmospheric Processes And their Role in Climate, https://www.aparc-climate.org/), a core project of the World Climate Research Program, which coordinates knowledge about the atmosphere in terms of climate variability and prediction. 

The GFZ contributes to the quantification of atmospheric temperature trends with its radio occultation data and analyses. 

Link: https://www.aparc-climate.org/activities/temperature-changes/