Abstract—
The dynamics of coronal holes (CHs) during the declining phase of solar cycle 24 is studied based on observational data from the Atmospheric Imaging Assembly (AIA), the 19.3 nm channel, of the Solar Dynamic Observatory (SDO). Some features of changes in the areas of polar and mid- and low-latitude CHs in the period April 1, 2014–December 31, 2019, are revealed by a comparison of the variations in the daily total CH area with the index of the sunspot number. The division of all CHs observed in the considered period into polar and nonpolar shows that polar-CH areas dominate and increase while nonpolar-CH areas constantly decrease toward the cycle minimum. Polar-CH areas account for ~80% of the total area of all CHs considered over the studied period. The total polar-CH area increases toward cycle minimum, which is consistent with the general concept of polar CHs as the main source of the Sun’s dipole magnetic field. However, the second subset, which contains selected isolated CHs, shows an interesting behavior in the declining phase of solar activity that was not previously observed. Their areas slowly decrease from the maximum to minimum of the solar cycle. This trend is qualitatively consistent with a decrease in sunspot activity toward the minimum, which suggests a physical relationship between the two phenomena.
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REFERENCES
Abramenko, V.I., Fisk, L.A., and Yurchyshyn, V.B., The rate of emergence of magnetic dipoles in coronal holes and adjacent quiet-Sun regions, Astrophys. J., 2006, vol. 641, no. 1, pp. L65–L68.
Abramenko, V., Yurchyshyn, V., Linker, J., et al., Low-latitude coronal holes at the minimum of the 23rd solar cycle, Astrophys. J., 2010, vol. 712, no. 2, pp. 813–818.
Andreeva, O.A., Akhmetov, Z.S., Malashchuk, V.M., et al., Study of variations of some characteristics of the giant coronal hole of 2015–2017, Geomagn. Aeron. (Engl. Transl.), 2018, vol. 58, no. 7, pp. 916–924.
Andreeva, O.A., Abramenko, V.I., and Malashchuk, V.M., Coronal holes during the period of maximum asymmetry in the 24th solar activity cycle, Astrophysics, 2020, vol. 63, no. 1, pp. 114–124.
Barra, V., Delouille, V., Kretzschmar, M., and Hochedez, J.-F., Fast and robust segmentation of solar EUV images: Algorithm and results for solar cycle 23, Astron. Astrophys., 2009, vol. 505, no. 1, pp. 361–371.
Bilenko, I.A., Formation and evolution of different type coronal holes, in Multi-Wavelength Investigations of Solar Activity, Proceedings IAU Symposium, Stepanov, A.V., Benevolenskaya, E.E., and Kosovichev, A.G., Eds., 2004, vol. 223, pp. 373–374.
Bilenko, I.A. and Tavastsherna, K.S., Coronal hole and solar global magnetic field evolution in 1976–2012, Sol. Phys., 2016, vol. 291, pp. 2329–2352.
Bohlin, J.D. and Sheeley, N.R., Jr., Extreme ultraviolet observations of coronal holes, Sol. Phys., 1978, vol. 56, pp. 125–151.
Bravo, S. and Otaola, J.A., Polar coronal holes and the sunspot cycle: A new method to predict sunspot numbers, Sol. Phys., 1989, vol. 122, pp. 335–343.
Bravo, S. and Stewart, G.A., Evolution of polar coronal holes and sunspots during cycles 21 and 22, Sol. Phys., 1994, vol. 154, pp. 377–384.
Bravo, S. and Stewart, G.A., The correlation between sunspot and coronal hole cycles and a forecast of the maximum of sunspot cycle 23, Sol. Phys., 1997, vol. 173, no. 1, pp. 193–198.
Dorotovič, I., Area of polar coronal holes and sunspot activity: Years 1939–1993, Sol. Phys., 1996, vol. 167, pp. 419–426.
Hess Webber, S.A., Karna, N., Pesnell, W.D., and Kirk, M.S., Areas of polar coronal holes from 1996 through 2010, Sol. Phys., 2014, vol. 289, pp. 4047–4067.
Hoyng, P., Helicity fluctuations in mean field theory: An explanation for the variability of the solar cycle?, Astron. Astrophys., 1993, vol. 272, pp. 321–339.
Hurlburt, N., Cheung, M., Schrijver, C., et al., Heliophysics event knowledgebase for the Solar Dynamics Observatory (SDO) and beyond, Sol. Phys., 2012, vol. 275, pp. 67–78.
Ikhsanov, R. and Ivanov, V., Properties of space and time distribution of solar coronal holes, Sol. Phys., 1999, vol. 188, pp. 245–258.
Insley, J.E., Moore, V., and Harrison, R.A., The differential rotation of the corona as indicated by coronal holes, Sol. Phys., 1995, vol. 160, no. 1, pp. 1–18.
Levine, R.H., Large-scale solar magnetic fields and coronal holes, in CHs and High Speed Wind Streams, Zirker, J.B., Ed., Boulder, Col.: Colorado Univ. Press, 1977, pp. 103–143.
Levine, R.H., Altschuler, M.D., Harvey, J.W., and Jackson, B.V., Open magnetic structures on the Sun, Astrophys. J., 1977, vol. 215, pp. 636–651.
Malashchuk, V.M., Fainshtein, V.G., Stepanyan, N.N., and Rudenko, G.V., Connection of coronal holes with active regions, Bull. Crimean Astrophys. Obs., 2012, vol. 108, no. 1, pp. 64–69.
Obridko, V.N. and Shelting, B.D., Global complexes of activity, Astron. Rep., 2013, vol. 57, no. 10, pp. 786–796.
Obridko, V.N. and Shelting, B.D., Coronal holes in global complexes of activity, Adv. Astron., 2015, vol. 2015, pp. 1–9.
Sanchez-Ibarra, A. and Barraza-Paredes, M., Catalog of coronal holes, 1970–1991, Report UAG-102, Boulder, Col.: World Data Center A for Solar-Terrestrial Physics, National Geophysical Data Center,1992.
Sheeley, N.R., Jr. and Harvey, J.W., Coronal holes, solar wind streams, and geomagnetic disturbances during 1978 and 1979, J. High Resolut. Chromatogr. Chromatogr. Commun., 1981, vol. 70, pp. 237–249.
Verbeeck, C., Delouille, V., Mampaey, B., and De Viss-cher, R., The SPoCA-suite: Software for extraction, characterization, and tracking of active regions and coronal holes on EUV images, Astron. Astrophys., 2014, vol. 561, id A29.
Yazev, S.A., Coronal holes and solar activity complexes, Izv. Irkutsk. Gos. Univ.: Ser. Nauki Zemle, 2010, vol. 3, no. 2, pp. 226–241.
ACKNOWLEDGMENTS
The SDO is part of the Living with a Star program of the National Aeronautics and Space Administration. The SDO/AIA data were provided by the Joint Science Operation Center (JSOC). We thank the Heliophysics Event Knowledgebase (HEK) project team for access to the CH databases.
We are grateful to V.I. Abramenko for useful discussions, valuable suggestions, and critical comments.
We thank the anonymous reviewer whose comments and critiques made it possible to improve the article.
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Andreeva, O.A., Malashchuk, V.M. Sunspot Activity and Coronal Holes during the Declining Phase of Cycle 24. Geomagn. Aeron. 60, 1093–1100 (2020). https://doi.org/10.1134/S0016793220080022
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DOI: https://doi.org/10.1134/S0016793220080022