Invited speaker:

Niilo Kalakoski, FMI, will talk about their recent Nature paper: Polar mesospheric ozone loss initiates downward coupling of solar signal in the Northern Hemisphere https://www.nature.com/articles/s41467-025-55966-z

Time is local Finnish time (UTC+3)

Tuesday April 1, 2025

8.30 - 9.00 Registration 9.00 - 9.30 Opening and Welcome 9.00 - 9.15 Introduction and practical matters, Thomas Carlund, Chair of NOG, and Kaisa Lakkala, FMI 9.15 - 9.30 Opening by Johanna Tamminen, Unit Leader FMI

9:30 - 10:15 Session I 9.30 - 9.45 Svendby: Updates on Norwegian total ozone monitoring 9.45 - 10.00 Jønch-Sørensen: Ozone- and UV-measurements in Denmark and Greenland 10.00 - 10.15 Carlund: Ground-based total ozone, UV and total solar radiation measurements in Sweden

10:15 - 10.45 Coffee + posters

10:45 - 12.00 Session II 10.45 - 11.15 Invited speaker: Niilo Kalakoski, FMI, Polar mesospheric ozone loss initiates downward coupling of solar signal in the Northern Hemisphere 11.15 - 11.30 Doppler: UV, Ozone and SCR (Secondary Cosmic Rays) parallel measurements in the Euramet BIOSPHERE Project 11.30 - 11.45 Raffalski: Time series of Ozone observed during winter 2024/25 over Kiruna, Sweden 11.45 - 12.00 Sofieva: Ozone trends in the stratosphere derived using merged Ozone_CCI datasets

12:00 - 13:15 Lunch + posters

13:15 - 14:30 Session III 13.15 - 13.30 Cizkova: Total column ozone observations in Reykjavík, Iceland, 2021-2024 13.30 - 13.45 Kivi: Ozonesonde observations at Sodankylä, Finland 13.45 - 14.00 Tichopád: Assessment of the extremely low total ozone column in the Arctic region during February 2023 14.00 - 14.15 Mangold: Time series analysis of uv and total ozone measurements at Princess Elisabeth station, East Antarctica 14.15 - 14.30 Redondas: Brewer stop production implications

14:30 - 15:15 Coffee + posters

15:15 - 16:45 Session IV 15.15 - 15.25 Velazco: Evaluating the BTS Spectrometer for Total Ozone Column Measurements in an Arctic Environment 15.25 - 16.45 Egli: First analysis of the WMO-BTS for Sodankylä in comparison with improvements of the DAVOS-BTS at PMOD/WRC in Davos 15.45 - 16.00 Berjón: Brewer stray light corrections 16.00 - 16.15 Parra-Rojas: Uncertainty Implementation on total ozone EuBrewNet products 16.15 - 16.30 Savastiouk: Using AI for Brewer operation troubleshooting

19.00 Dinner (at your own expense), City center, Restaurant Gillet Bar & Bistro, Kasarmikatu 23

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Wednesday April 2, 2025

8:45 - 9:45 Session V 8.45 - 9.00 Kuittinen: Towards LED based UV sources for calibrations of solar UV equipment 9.00 - 9.15 Hülsen: Solar UV dosimeter calibrations in the frame of the MeLiDos EMP project 22NRM05 9.15 - 9.30 Hoftuft: Using pyranometer data to assess drift in multiband radiometers: Update 9.30 - 9.45 Skarta: Measurement-based quality for indoor UV light emitting devices

9:45 - 10:30 Coffee + posters

10:30 - 11:45 Session VI 10.30 - 10.45 Schmalwieser: Skin Colour and Pigmentation as biomarkers for personal UV-Exposure? 10.45 - 11.00 Robson:Interactive effects of UV radiation, climate and stratospheric ozone depletion on polar and alpine ecosystems, photodegradation of plant material and of pesticides. 11.00 - 11.15 Lorenz: Long-term Solar UV Monitoring (Part I): Data and Trend Results from Dortmund, Germany and Uccle, Belgium 11.15 - 11.30 Heinzl: Long-term Solar UV Monitoring (Part II): Trend Model and Imputation Method for Data Gap Handling 11.30 - 11.45 Johnsen: Three decades of UV monitoring in Norway, including Svalbard

11:45 - 13:15 Lunch + posters

13.15 - 14.45 Session VII 13.15 - 13.30 Kujanpää: Satellite UV activities at FMI 13.30 - 13.45 Klotz: UV Map Nowcasting and Comparison with Ground-Based UV Measurements for the DACH Region 13.45 - 14.00 Lakkala: UV measurements at Sodankylä, FMI

14.00 – 15:00 Coffee + Formal matters (next meeting) + final discussion + closing

15:00 – 16:00 Visit to FMI's roof to see the solar radiation measurements and to FMI's optical laboratories