EOMF-32. Updated Trends of the Stratospheric Ozone Vertical Distribution at Select NOAA Global Monitoring Laboratory Dobson Monitoring Stations Based on the LOTUS Regression Model

This study presents an updated evaluation of stratospheric ozone profile trends at Arosa, Switzerland (46.8N, 9.68E), Boulder, Colorado (40.0N, 105.3W), Haute Provence, France (43.9N, 5.8E), Lauder, New Zealand (45.04S, 169.68E), and Mauna Loa, Hawaii (19.5N, 155.58W) with focus on the 2000–2020 period. Trends are derived using vertical ozone profiles from NOAA’s Dobson Network via the Umkehr method (with a recent new homogenization), ozonesondes, and the cohesive satellite-based record (COH) overpasses of the stations. Analyses were performed using the updated version (0.8.0) of the Long-term Ozone Trends and Uncertainties in the Stratosphere (LOTUS) Independent Linear Trend regression model. We discuss the consistency of the trends derived from the different records, which is key to the understanding of the recovery of the ozone layer after the implementation of the Montreal Protocol. The Northern Hemispheric sites of Arosa, Haute Provence, and Mauna Loa all show positive trends in the mid to upper Stratosphere with trends peaking at ~2%/decade. Trends in the upper stratosphere at Boulder and Lauder are positive, but not statistically significant. In the lower stratosphere, trends are mostly negative. Significant trends were found at Mauna Loa and Lauder. However, the lower stratospheric trend uncertainties are quite large. Additionally, the Equivalent Latitude was investigated as an additional dynamical proxy in the LOTUS model at these sites. We will discuss the addition of the proxy and its impact on the trends and uncertainties.