Speaker
Description
After a first successful phase of the Tropospheric Ozone Assessment Report (TOAR), which e.g. provided the first global scale view of all available surface ozone observations, the most extensive evaluation of historical (pre 1975) ozone observations and the first intercomparison of satellite ozone products, TOAR is now nearly the end of its second phase (TOAR-II, 2020-2024). TOAR-II will produce an updated assessment of tropospheric ozone’s global distribution and trends, along with distributions and trends of ozone precursor emissions, and aims to quantify the impacts of tropospheric ozone on climate, human health and vegetation (e.g., crops).
One primary goal of TOAR-II is to understand the wide variety of distribution, trends and variability in (free-)tropospheric ozone measured with satellites in TOAR-I and reported in Gaudel et al. (2018). Therefore, it is required to characterize the effects of differences in measurement vertical sensitivity and sampling on the tropospheric ozone distribution and trends. Different TOAR-II Focus Working Groups try to address this challenge from their own perspectives (satellite data, ground-based and in-situ data, and chemical reanalysis model output), but with the harmonization of the tropospheric ozone data as a necessary, intermediate step.
In this contribution, we will report on the harmonization activities in the satellite ozone and HEGIFTOM (“Harmonization and Evaluation of Ground-based Instruments for Free-Tropospheric Ozone Measurements”) focus working groups and present some first results of worldwide tropospheric ozone column trend estimates.
