Tropospheric ozone from IASI : regional and global assessment

Tropospheric ozone (O3) is an important greenhouse gas and air pollutant. It is the primary source of the most important oxidant in the atmosphere, the hydroxyl radical OH, that is highly reactive with organic and inorganic compounds. Global tropospheric O3 concentrations have been rising considerably since pre-industrial times as a result of the increase in the anthropogenic emissions of O3 precursors. In this thesis, I will study the temporal and spatial variability of tropospheric O3 on a global and regional scale as measured by IASI (Infrared Atmospheric Sounding Interferometer). The IASI instruments have been launched on-board the MetOp-A and MetOp-B satellites in 2006 and 2012.I first discuss the IASI/O3 measurements, their sensitivity in the troposphere and their seasonal variation and transport processes. I then perform more detailed and focused studies. Those include studying the urban and rural O3 and its relationship with nitrogen dioxyde (NO2) measured from GOME (Global Ozone Monitoring Experiment) over different cities in the Northern Hemisphere; investigating the summertime tropospheric O3 maxima over the Mediterranean region using IASI and the WRF-Chem (Weather Research and Forecasting model coupled with Chemistry) data; and finally, using both satellite and model data, I present my analysis of the East Asian monsoon variability and its effect on the tropospheric O3 column.