Keywords: Ozone vertical distribution in the upper troposphere – lower stratosphere over Ukraine based on the EAC4 reanalysis data

The paper examines the vertical distribution of O3 over the territory of Ukraine in the upper troposphere – lower stratosphere layer, its seasonal variability, and interannual trends. The study was conducted using data from the European Centre for Medium-Range Weather Forecasts (ECMWF) Atmospheric Composition Reanalysis 4 (EAC4) for the period 2003–2023. It is shown that the vertical distribution of O3 below the 30 hPa isobaric level is primarily shaped by the dominant role of the Brewer–Dobson circulation, whereas above this level photochemical reactions become the determining factor. According to EAC4 data, the long-term mean O3 maxima at these levels reach 12 mg/kg, decreasing to 2 mg/kg in the upper troposphere. The EAC4 reanalysis is shown to overestimate the altitudes at which the maximum O3 content is observed (10–20 hPa), compared with the mean levels derived from observations (30–50 hPa). Depending on the season, the timing of higher concentrations varies with altitude. Up to the 30 hPa level, winter–spring O3 maxima prevail as a result of transport by the Brewer–Dobson circulation, whereas above this level, summer maxima occur due to more intensive photochemical production. During the study period, a decrease in O3 was identified in the 50–100 hPa layer (16–20 km), occurring most intensively in the summer and winter seasons, with a decline rate of 0.02 mg/kg per year. In contrast, above the 10 hPa level (above 30 km), O3 increases due to interannual changes in the spring season, with an upward trend of approximately 0.03 mg/kg per year. The obtained results provide an important addition to the known patterns of O3 distribution over Ukraine in terms of identifying the causes of ozone layer variability, which may have implications for the frequency of elevated levels of ultraviolet radiation harmful to human health and ecosystems.

1. Andrienko, Yu., Milinevsky, G., Danylevsky, V. (2021). Vertical ozone profiles in the atmosphere over the Antarctic Peninsula and Kyiv by Umkehr observations. Ukrainian Antarctic Journal, 2, 35–47. https://doi.org/10.33275/1727-7485.2.2021.676

2. Barnes, P.W., Williamson, C.E., Lucas, R.M., Robinson, S.A., Madronich, S., Paul, N.D., Bornman, J.F., Bais, A.F., Sulzberger, B., Wilson, S.R., Andrady, A.L., McKenzie, R.L., Neale, P.J., Austin, A.T., Bernhard, G.H., Solomon, K.R., Neale, R.E., Young, P.J., Norval, M., Rhodes, L.E., Hylander, S., Rose, K.C., Longstreth, J., Aucamp, P.J., Ballare, C.L., Cory, R.M., Flint, S.D., de Gruijl, F.R., Hader, D.-P., Heikkila, A.M., Jansen, M.A.K., Pandey, K.K., Robson, T.M., Sinclair, C.A., Wangberg, S., Worrest, R.C., Yazar, S., Young, A.R., Zepp, R.G. (2019). Ozone depletion, ultraviolet radiation, climate change and prospects for a sustainable future. Nature Sustainability, 2, 569-579, https://doi.org/10.1038/s41893-019-0314-2

3. Butchart, N. (2014). The Brewer‐Dobson circulation. Reviews of Geophysics, 52(2), 157–184. https://doi.org/10.1002/2013RG000448

4. Cracknell, A.P., Varotsos, C. (2012). Remote Sensing and Atmospheric Ozone. Springer Berlin Heidelberg. https://doi.org/10.1007/978-3-642-10334-6

5. Dvoretska, I.V. (2012). The features of total ozone dynamics during the modern period. Naukovi pratsi UkrNDGMI, 262, 257-271.

6. Dvoretska, I.V., Savenets, M.V., Umanets, A.P. (2021). Updated total ozone climate normals over the territory of Ukraine. Ukrainian Hydrometeorological Journal, 28, 5-15. https://doi.org/10.31481/uhmj.28.2021.01

7. Fernandez, R.P., Berná, L., Tomazzeli, O.G., Mahajan, A.S., Li, Q., Kinnison, D.E., Wang, S., Lamarque, J.-F., Tilmes, S., Skov, H., Cuevas, C.A., Saiz-Lopez, A. (2024). Arctic halogens reduce ozone in the northern mid-latitudes. Proceedings of the National Academy of Sciences, 121(39). https://doi.org/10.1073/pnas.2401975121

8. Galytska, E., Rozanov, A., Chipperfield, M.P., Dhomse Sandip, S., Weber, M., Arosio, C., Feng, W., Burrows, J.P. (2019). Dynamically controlled ozone decline in the tropical mid-stratosphere observed by SCIAMACHY. Atmospheric Chemistry and Physics, 19, 767–783. https://doi.org/10.5194/acp-19-767-2019.

9. Grytsai, A.V., Milinevsky, G.P. (2018). Total ozone content over KYIV-GOLOSEYEV station by ground-based and satellite measurements in 2010–2015. Space Science and Technology, 24(3), 40-54. https://doi.org/10.15407/knit2018.03.040

10. Hartmann, D. L. (2022). The Antarctic ozone hole and the pattern effect on climate sensitivity. Proceedings of the National Academy of Sciences, 119(35). https://doi.org/10.1073/pnas.2207889119

11. Hu, D., Shi, S., Wang Z. (2023). Link between Arctic ozone and the stratospheric polar vortex. Atmospheric and Oceanic Science Letters, 16(1), 100293. https://doi.org/10.1016/j.aosl.2022.100293

12. Inness, A., Ades, M., Agustí-Panareda, A., Barré, J., Benedictow, A., Blechschmidt, A-M., Dominguez, J.J., Engelen, R., Eskes, H., Flemming, J., Huijnen, V., Jones, L., Kipling, Z., Massart, S., Parrington, M., Peuch, V.-H., Razinger, M., Remy, S., Schulz, M., Suttie, M. (2019). The CAMS reanalysis of atmospheric composition. Atmospheric Chemistry and Physics, 19, 3515–3556. https://doi.org/10.5194/acp-19-3515-2019

13. Khanna, T., Shraim, R., Zarkovic, M., van Weele, M., van Geffen, J., Zgaga, L. (2022). Comprehensive Analysis of Seasonal and Geographical Variation in UVB Radiation Relevant for Vitamin D Production in Europe. Nutrients, 14(23), 5189. https://doi.org/10.3390/nu14235189

14. Kracher, D., Reick, C.H., Manzini, E., Schultz, M.G., Stein, O. (2016). Climate change reduces warming potential of nitrous oxide by an enhanced Brewer-Dobson circulation. Geophysical Research Letters, 43(11), 5851-5859. https://doi.org/10.1002/2016GL068390

15. Ladstädter, F., Stocker, M., Scher, S., Steiner, A.K. (2025). Observed changes in the temperature and height of the globally resolved lapserate tropopause. Atmospheric Chemistry and Physics, 25, 16053–16062. https://doi.org/10.5194/acp-25-16053-2025

16. Milinevsky, G., Grytsai, A., Evtushevsky, O., Danylevsky, V., Udodov, E., Gladikov, D. (2013). Vertical ozone distribution features in the atmosphere over midlatitude Kyiv-Goloseyev station. EGU General Assembly 2013, EGU2013-6148. https://ui.adsabs.harvard.edu/abs/2013EGUGA..15.6148M/abstract

17. Milinevsky, G.P., Andrienko, Yu., Ivaniha, O., Grytsai, A., Agapitov, O.V., Evtushevsky, O.M., Shi, Y. (2022). Vertical ozone distribution changes by Umkehr measurements, satellite data and MERRA-2 reanalysis over midlatitude station. AGU Fall Meeting 2022, A54H-10. https://ui.adsabs.harvard.edu/abs/2022AGUFM.A54H..10M/abstract

18. Mogylchak, V.Y., Milinevsky, G.P. (2017). Variations of total ozone in the atmosphere over the territory of Ukraine. Space Science and Technology, 23(2), 41-47. https://doi.org/10.15407/knit2017.02.041

19. Park, S., Son, S.W., Jung, M.I., Park J., Park, S.S. (2020). Evaluation of tropospheric ozone reanalyses with independent ozonesonde observations in East Asia. Geoscience Letters, 7, 12 (2020). https://doi.org/10.1186/s40562-020-00161-9

20. Petropavlovskikh, I., Miyagawa, K., McClure-Beegle, A., Johnson, B., Wild, J., Strahan, S., Wargan, K., Querel, R., Flynn, L., Beach, E., Ancellet, G., Godin-Beekmann, S. (2022). Optimized Umkehr profile algorithm for ozone trend analyses. Atmospheric Measurements. Techniques, 15, 1849–1870. https://doi.org/10.5194/amt-15-1849-2022

21. Polvani, L.M., Abalos, M., Garcia, R., Kinnison, D., Randel, W.J. (2017). Significant Weakening of Brewer-Dobson Circulation Trends Over the 21st Century as a Consequence of the Montreal Protocol. Geophysical Research Letters, 45(1), 401-409. https://doi.org/10.1002/2017GL075345

22. Rolf, M. (2009). A brief history of stratospheric ozone research. Meteorologische Zeitschrift, 18(1), 3-24. https://doi.org/10.1127/0941-2948/2009/353

23. Roscoe, H. K. (2006). The Brewer–Dobson circulation in the stratosphere and mesosphere – Is there a trend? Advances in Space Research, 38(11), 2446–2451. https://doi.org/10.1016/j.asr.2006.02.078

24. Shangguan, M., Wang, W., Jin, S. (2019). Variability of temperature and ozone in the upper troposphere and lower stratosphere from multi-satellite observations and reanalysis data. Atmospheric Chemistry and Physics, 19, 6659–6679. https://doi.org/10.5194/acp-19-6659-2019

25. Shi, Y., Evtushevsky, O., Milinevsky, G., Klekociuk, A., Han, W., Ivaniha, O., Andrienko, Y., Shulga, V., Zhang, C. (2022). Zonal Asymmetry of the Stratopause in the 2019/2020 Arctic Winter. Remote Sensing, 14, 1496. https://doi.org/10.3390/rs14061496

26. Staehelin, J., Petropavlovskikh, I., de Mazière, M., Godin-Beekmann, S. (2018). The role and performance of ground-based networks in tracking the evolution of the ozone layer. Comptes Rendus. Géoscience, 350(7), 354–367. https://doi.org/10.1016/j.crte.2018.08.007

27. Umanets A, Krainyk S, Savenets M. (2024). Dynamical conditions of the spatial extremes formation in ozone layer over the territory of Ukraine. Meteorology. Hydrology. Environmental monitoring 1(5):89-99. http://doi.org/10.15407/Meteorology2024.05.089

28. Van Noije, T.P.C., Eskes, H.J., van Weele, M., van Velthoven, P.F.J. (2004). Implications of the enhanced Brewer‐Dobson circulation in European Centre for Medium‐Range Weather Forecasts reanalysis ERA‐40 for the stratosphere‐troposphere exchange of ozone in global chemistry transport models. Journal of Geophysical Research: Atmospheres, 109(D19). https://doi.org/10.1029/2004JD004586

29. Zou, J., Walker, K.A., Sheese, P.E., Boone, C.D., Stauffer, R.M., Thompson, A.M., Tarasick, D.W. (2024). Validation of ACE-FTS version 5.2 ozone data with ozonesonde measurements, Atmospheric Measurements. Techniques, 17, 6983–7005. https://doi.org/10.5194/amt-17-6983-2024