Extremely large flares/multiple large flares expected from sunspot groups with large area

Abstract The possible occurrence of major space weather events, such as large solar flares within one hundred years, is studied anticipating their effects on our social facilities. However, the continuous soft X-ray (SXR) observation by Geostationary Operational Environmental Satellites (GOES) started in 1975, and period data collection less than 50 years. On other hand, ground-based sunspot observations have a long history. Their duration exceeds 100 possibility extremely estimated using daily area individual groups between 1879 2016 catalogue complied Debrecen Heliophysical Observatory Hungary updated Mandal, Krivova, Solanki, Shinha, Banerjee 2020. It had become clear that with potential to produce Carrington-class (areas more 3000 MSH) appeared total 119−139 days 2016, group an X100-class flare March April 1947. According past caused series multiple instead just flare. We tried estimate probabilities SXR $$\ge$$ ≥ X100 for 30-, 50-, 100-year periods be 0.70−0.76, 0.87−0.91, 0.98−0.99, respectively, complementary cumulative distribution function (CCDF) areas 138-year data. Graphical