aat Acta Astrophys. Tau. Acta Astrophysica Taurica 2712-925X Kiselev Nikolai Nikolaevich, Mosсow, settlement Moskovskii, Tat'yanin Park Str., 12, Moscow, Russia. RU 23 10.34898/aat.vol3.iss2.pp12-16 Magnetism and activity of the Sun and stars – 2021 Conference proceedings Polar regions activity and the prediction of the height of the solar cycle 25 Koutchmy Serge Filippov Boris Tavabi E. Noëns J-C. Wurmser O. Institut d’Astrophysique de Paris, CNRS and Sorbonne University, UMR 7095-98 Bis Boulevard Arago, Paris 75014, France Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk 108840, Russia Physics Department, Payame Noor University (PNU), 19395-3697, Tehran, I. R. of Iran Obs. Pic du Midi, Association des O.A., France Association des O.A., PdM, France 15 06 2022 3 2 12 16 29 10 2021 Copyright (c) Koutchmy S., Filippov B., Tavabi E., Noëns J., Wurmser O. Koutchmy S., Filippov B., Tavabi E., Noëns J., Wurmser O. The metadata for this submission is licensed under a Creative Commons Attribution 4.0 International License. Copyright and publishing rights for texts published in Acta Astrophysica Taurica is retained by the authors, with first publication rights granted to the journal.Texts are free to use with proper attribution and link to the licensing (Creative Commons Attribution 4.0 International).

The forthcoming solar cycle (SC) 25 was believed to be rather low when the sunspot number (SN) is used as a measure of the activity level. The most popular prediction was made by the NOAA/NASA Solar Cycle 25 Prediction Panel in 2019, including works based on dynamo-type models. However, we discovered that the height of SC25 could be high, using different observations for measurements of the level of the polar-region activity above the limb at high latitudes several years before the start of SC25 and also after its beginning in 2020. The polar-region activity, which we consider, seems to be related to the polar coronal-hole (CH) activity, and it was significantly higher before SC25 than before SC24. It is also possibly reflected in the so-called chromospheric prolateness observed at solar minimum. Accordingly, we suggest that SC25 could indeed be significantly higher than SC24, which was a very low SN cycle.

solar cycle cycle 25 polar regions activity polar faculae X-ray bright points macro-spicules polar mini ejections chromospheric prolateness Filippov B., Koutchmy S., 2000. Solar Phys., vol. 196, no. 2, pp. 311–320. Filippov B., Koutchmy S., Vilinga J., 2007. Astron. Astrophys., vol. 464, no. 3, pp. 1119–1125. Kitiashvili I.N., 2020. In Kosovichev A.G., Strassmeier K., and Jardine M. (Eds), Solar and Stellar Magnetic Fields: Origins and Manifestations, Proceedings IAU Symposium, vol. 354, pp. 147–156. Kitiashvili I.N., 2021. Mon. Not. Roy. Astron. Soc., vol. 505, iss. 4, pp. 6085–6102. Koutchmy S., di Folco E., Auchere Fr., et al., 1999. In Vial J.-C. and Kaldeich-Schu B. (Eds), 8th SOHO Workshop: Plasma Dynamics and Diagnostics in the Solar Transition Region and Corona, ESA Special Publication, vol. 446, p. 385. Makarov V.I., Leroy J.L., Noens J.C., 1987. Sov. Astron., vol. 31, p. 560. Murray N., 1992. Solar Phys., vol. 38, pp. 419–422. Nandy D., 2021. Solar Phys., vol. 296, no. 3, eid. 54. Noens J.-C., Wurmser O., 2000. Astrophys. Space Sci., vol. 273, pp. 17–23. Svalgaard L., Duvall T.L., Scherrer P.H., 1978. Solar Phys., vol. 58, pp. 225–239. Tlatov A.G. 2009. Solar Phys., vol. 260, pp. 465–477. Tlatov A.G. and Tlatova K.A., 2020. Geomagnetism and Aeronomy, vol. 60, no. 7, pp. 825–830.