Detection of tropospheric ozone from IASI during exceptional events

International audienceAs an important greenhouse gas and air pollutant, tropospheric ozone (O3) has become a significantenvironmental and climate concern. Both strong local photochemical production within thetroposphere and transport from the stratosphere can lead to elevated tropospheric O3 concentrations.These have increased globally over the last century due to enhanced anthropogenic precursoremissions. Monitoring of tropospheric O3 is therefore essential to understand its impact on airquality, chemical composition and climate change.Although quantifying tropospheric O3 from space is difficult because of the abundance of ozone inthe stratosphere, over the past decade satellite instruments have provided valuable information on itsdistribution and temporal evolution. Here, we use the IASI instrument to retrieve tropospheric O3from space and assess its ability to detect ozone in the lower troposphere during exceptional events,such as photochemical smogs. We use the WRF-Chem chemical transport model to interpretobservations of tropospheric O3 from IASI, and to assess the meteorological and dynamical processesinvolved in such extreme events