Twenty years after the peak of ozone depleting substances in the stratosphere, a clear understanding of ozone trends and their significance as a function of altitude and latitude is still needed. Following the SI2N activity (sponsored by SPARC, IO3C, IGACO-O3/UV and NDACC) that evaluated ozone profile trends from long-term satellite and ground-based records, the LOTUS activity aims at providing a clear evaluation of uncertainties in trend studies and in particular the consideration of errors linked to e.g. the sampling and the stability of (merged) data sets that could not be achieved by the end of SI2N in 2015.
The activity Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) was initiated in 2016 and its objectives are
- to update and extend stratospheric ozone observations to recent years,
- to improve our understanding of crucial yet poorly known sources of uncertainties in trend retrieval,
- to investigate how uncertainties interact and propagate through the different stages of analysis chain, and
- to re-evaluate current best practice(s) and possibly establish more suitable alternatives.