This session focuses on the variability of the tropospheric and stratospheric chemical composition on diurnal, seasonal and longer timescales. Emphasis is put on the scientific value of long-term measurement time series and supporting model simulations. Both approaches contribute to improved understanding of the mechanisms which control interannual to decadal variability of atmospheric constituents (including variety of greenhouse and reactive gases). Future projects of the atmospheric composition are included in this session as well.
Researchers are invited to present novel scientific results from mid- and long-term observational time series from various measurement programmes and networks such as the Global Atmosphere Watch (GAW) Programme, European Monitoring and Evaluation Programme (EMEP), Network for the Detection of Atmospheric Composition Change (NDACC), Southern Hemisphere Additional Ozonesondes (SHADOZ), Advanced Global Atmospheric Gases Experiment (AGAGE), National Oceanic and Atmospheric Administration (NOAA), regular airborne (e.g. CARIBIC, IAGOS, CONTRAIL) and other campaigns as well as satellite data and model simulations. Data relevant to tropospheric and stratospheric composition, in particular related to ozone depletion, climate change and air quality as well as firn data on past atmospheric composition are welcome. We welcome contributions from multi-year modeling studies and inter-comparison exercises which address past and future tropospheric or stratospheric composition changes, carried out in the framework of international projects (e.g. MACC) and initiatives (IGAC’s Atmospheric Chemistry and Climate, TFMM, HTAP and others).