The third SPARC/WMO Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) workshop originally planned for Helsinki was held virtually May 28-29, 2020. Topics included ozonesonde total ozone drop-off, opportunities from ozone monitoring super-sites, dataset homogenization updates and improvements, gridded ozone datasets, climate models, tropospheric ozone, trend model improvements, and local solar time and seasonal studies.
LOTUS focuses on revisiting the estimates and understanding of ozone trends in support of the WMO/UNEPOzone Assessments. The LOTUS report was accepted for publication in May 2018, completing the main objective of the first phase of the activity. The second phase updates ozone records, includes a more significant evaluation of ground data records, optimizes the trend models, extends emphasis to polar regions and the lower stratosphere, and examines the relation between total and stratospheric ozone behavior. LOTUS has created a relationship to TOAR and OCTAV-UTLS collaborators and will share data with them.