During recent years substantial progress has been made in the development and application of ground-based techniques for remote sounding of greenhouse gases. A variety of new or improved sounding systems yields information on both total columns and vertical profiles covering the altitude range from the surface up to the mesosphere. This information is complementary to the information from surface in situ networks and satellite missions, and is utilized for studies of variability and trends, inversion of sources and sinks as well as for satellite validation.

This session is open to papers on all kind of new instrumental developments (e.g., FTIR, micro wave, lidar, including intercomparisons to other instruments) and new retrieval approaches for deriving information on greenhouse gases from existing and newly established measurement time series. There will be a focus on CO2, CH4, N2O, and H2O, but contributions dealing with further greenhouse gases like SF6 or CFC´s are encouraged as well. Preferably, but not exclusively contributions from international networks like NDACC (Network for the Detection of Atmospheric Composition Change) or TCCON (Total Carbon Column Observing Network) are invited. The session includes papers on the interpretation of measured variability and trends as well as satellite validation studies, and all kind of related modeling studies.