Abstract
Sunspot groups are the main source of solar flares, with the energy to power them being supplied by magnetic-field evolution (e.g. flux emergence or twisting/shearing). To date, few studies have investigated the statistical relation between sunspot-group evolution and flaring, with none considering evolution in the McIntosh classification scheme. Here we present a statistical analysis of sunspot groups from Solar Cycle 22, focusing on 24-hour changes in the three McIntosh classification components. Evolution-dependent \(\ge \mathrm{C}1.0\), \(\ge \mathrm{M}1.0\), and \(\ge \mathrm{X}1.0\) flaring rates are calculated, leading to the following results: i) flaring rates become increasingly higher for greater degrees of upward evolution through the McIntosh classes, with the opposite found for downward evolution; ii) the highest flaring rates are found for upward evolution from larger, more complex, classes (e.g. Zurich D- and E-classes evolving upward to F-class produce \(\ge \mathrm{C}1.0\) rates of \(2.66\pm 0.28\) and \(2.31 \pm 0.09\) flares per 24 hours, respectively); iii) increasingly complex classes give higher rates for all flare magnitudes, even when sunspot groups do not evolve over 24 hours. These results support the hypothesis that injection of magnetic energy by flux emergence (i.e. increasing in Zurich or compactness classes) leads to a higher frequency and magnitude of flaring.
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Notes
Note, there is no upper limit to the longitudinal extent of a B-class sunspot group indicated in Table 1, but these groups are typically of smaller extent.
References
Bloomfield, D.S., Higgins, P.A., McAteer, R.T.J., Gallagher, P.T.: 2012, Toward reliable benchmarking of solar flare forecasting methods. Astrophys. J. Lett. 747, L41. DOI . ADS .
Bloomfield, D.S., Gallagher, P.T., Marquette, W.H., Milligan, R.O., Canfield, R.C.: 2016, Performance of major flare watches from the max millennium program (2001 – 2010). Solar Phys. 291, 411. DOI . ADS .
Bornmann, P.L., Shaw, D.: 1994, Flare rates and the McIntosh active-region classifications. Solar Phys. 150, 127. DOI . ADS .
Cortie, A.L.: 1901, On the types of sun-spot disturbances. Astrophys. J. 13, 260. DOI . ADS .
Crown, M.D.: 2012, Validation of the NOAA Space Weather Prediction Center’s solar flare forecasting look-up table and forecaster-issued probabilities. Space Weather 10, S06006. DOI . ADS .
Emslie, A.G., Dennis, B.R., Shih, A.Y., Chamberlin, P.C., Mewaldt, R.A., Moore, C.S., et al.: 2012, Global energetics of thirty-eight large solar eruptive events. Astrophys. J. 759, 71. DOI . ADS .
Falconer, D.A., Moore, R.L., Gary, G.A.: 2008, Magnetogram measures of total nonpotentiality for prediction of solar coronal mass ejections from active regions of any degree of magnetic complexity. Astrophys. J. 689, 1433. DOI . ADS .
Gallagher, P.T., Moon, Y.-J., Wang, H.: 2002, Active-region monitoring and flare forecasting, I: data processing and first results. Solar Phys. 209, 171. DOI . ADS .
Georgoulis, M.K., Rust, D.M.: 2007, Quantitative forecasting of major solar flares. Astrophys. J. Lett. 661, L109. DOI . ADS .
Giovanelli, R.G.: 1939, The relations between eruptions and sunspots. Astrophys. J. 89, 555. DOI . ADS .
Hahn, M., Gaard, S., Jibben, P., Canfield, R.C., Nandy, D.: 2005, Spatial relationship between twist in active region magnetic fields and solar flares. Astrophys. J. 629, 1135. DOI . ADS .
Hale, G.E., Ellerman, F., Nicholson, S.B., Joy, A.H.: 1919, The magnetic polarity of sun-spots. Astrophys. J. 49, 153. DOI . ADS .
Künzel, H.: 1960, Die Flare-Häufigkeit in Fleckengruppen unterschiedlicher Klasse und magnetischer Struktur. Astron. Nachr. 285, 271. DOI . ADS .
Lee, K., Moon, Y.-J., Lee, J.-Y., Lee, K.-S., Na, H.: 2012, Solar flare occurrence rate and probability in terms of the sunspot classification supplemented with sunspot area and its changes. Solar Phys. 281, 639. DOI . ADS .
McIntosh, P.S.: 1990, The classification of sunspot groups. Solar Phys. 125, 251. DOI . ADS .
Murray, S.A., Bloomfield, D.S., Gallagher, P.T.: 2012, The evolution of sunspot magnetic fields associated with a solar flare. Solar Phys. 277, 45. DOI . ADS .
Murray, S.A., Bloomfield, D.S., Gallagher, P.T.: 2013, Evidence for partial Taylor relaxation from changes in magnetic geometry and energy during a solar flare. Astron. Astrophys. 550, A119. DOI . ADS .
Sammis, I., Tang, F., Zirin, H.: 2000, The dependence of large flare occurrence on the magnetic structure of sunspots. Astrophys. J. 540, 583. DOI . ADS .
Schmieder, B., Hagyard, M.J., Guoxiang, A., Hongqi, Z., Kalman, B., Gyori, L., et al.: 1994, Relationship between magnetic field evolution and flaring sites in AR 6659 in June 1991. Solar Phys. 150, 199. DOI . ADS .
Schrijver, C.J.: 2007, A characteristic magnetic field pattern associated with all major solar flares and its use in flare forecasting. Astrophys. J. Lett. 655, L117. DOI . ADS .
Schrijver, C.J., De Rosa, M.L., Title, A.M., Metcalf, T.R.: 2005, The nonpotentiality of active-region coronae and the dynamics of the photospheric magnetic field. Astrophys. J. 628, 501. DOI . ADS .
Snodgrass, H.B., Ulrich, R.K.: 1990, Rotation of Doppler features in the solar photosphere. Astrophys. J. 351, 309. DOI . ADS .
Vršnak, B., Žic, T., Vrbanec, D., Temmer, M., Rollett, T., Möstl, C., et al.: 2013, Propagation of interplanetary coronal mass ejections: the drag-based model. Solar Phys. 285, 295. DOI . ADS .
Waldmeier, M.: 1947, Heliographische Karten der Photosphäre für das Jahr 1946. Publ. Zür. Obs. 9, 1.
Wheatland, M.S.: 2001, Rates of flaring in individual active regions. Solar Phys. 203, 87. DOI . ADS .
Acknowledgements
The authors thank Chris Balch (NOAA/SWPC) for providing the data used in this research. A.E. McCloskey was supported by an Irish Research Council Government of Ireland Postgraduate Scholarship, while D.S. Bloomfield was supported by the European Space Agency PRODEX Programme as well as the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 640216 (FLARECAST project).
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Appendices
Appendix A: Zurich Class
Here we present accompanying tables and figures for the McIntosh Zurich class analysis. Evolution-dependent occurrence numbers and flaring rates of sunspot groups within \(\pm75^{\circ}\) longitude are provided in Tables 4 and 5, respectively. These data correspond directly to that presented in Figures 2 and 3, respectively. In addition, evolution-dependent flaring rates for the east and west limb regions (i.e. \(>75^{\circ}\) heliographic longitude) are displayed in Figures 4 and 5, respectively, for direct comparison to the “within \(\pm75^{\circ}\) longitude” case presented in Figure 3.
Appendix B: Penumbral Class
Here we present equivalent tables and figures for the McIntosh penumbral class analysis. Frequency histograms of each penumbral class are shown in the left column of Figure 6, while overall evolution steps on a 24-hour timescale are given in the right column of Figure 6 as percentage occurrence. Evolution-dependent occurrence numbers are provided in Table 6 and graphically represented in Figure 7 (equivalent to the Zurich class Table 4 and Figure 2, respectively). Finally, flaring rates of sunspot groups within \(\pm75^{\circ}\) longitude are provided in Table 7 and graphically represented in Figure 8 (equivalent to the Zurich class Table 5 and Figure 3, respectively).
Appendix C: Compactness Class
Here we present equivalent tables and figures for the McIntosh compactness class analysis. Frequency histograms of each compactness class are shown in the left column of Figure 9, while overall evolution steps on a 24-hour timescale are given in the right column of Figure 9 as percentage occurrence. Evolution-dependent occurrence numbers are provided in Table 8 and graphically represented in Figure 10 (equivalent to the Zurich class Table 4 and Figure 2, respectively). Finally, flaring rates of sunspot groups within \(\pm75^{\circ}\) longitude are provided in Table 9 and graphically represented in Figure 11 (equivalent to the Zurich class Table 5 and Figure 3, respectively).
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McCloskey, A.E., Gallagher, P.T. & Bloomfield, D.S. Flaring Rates and the Evolution of Sunspot Group McIntosh Classifications. Sol Phys 291, 1711–1738 (2016). https://doi.org/10.1007/s11207-016-0933-y
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DOI: https://doi.org/10.1007/s11207-016-0933-y