Forecasting SEP events with same active region prior flares

Forecasting large solar energetic (E > 10 MeV) particle (SEP) events is currently based on observed solar X-ray flare peak fluxes or fluences. Recent work has indicated that the probability of a solar eruptive event in an active region (AR) is enhanced when a large flare has occurred in that AR during the previous day. In addition, peak intensities Sp of SEP events associated with fast coronal mass ejections (CMEs) are larger for CMEs with prior CMEs from the same associated ARs in the previous day. This suggests that the associated SEP event probability and/or Sp may be higher for a given solar X-ray flare with a recent prior major flare in the same AR. We use data sets of NOAA flares and SEP events from solar cycles 22–24 to test this idea statistically for periods of prior flares ranging from 12 to 48 h. The occurrence probabilities and Sp of large SEP events for flares with prior same AR major (≥ M2) flares are not significantly higher than for flares without the prior flares; hence, prior flare occurrence is not a useful SEP event forecasting tool. The flare-based occurrence probabilities are higher for cycle 24 than for cycles 22 and 23, but the dependence of Sp on X-ray fluence appears unchanged. We show an example of a recent flare-prolific AR for which the SEP-associated flares are spatially distinct from the numerous non-SEP associated flares, indicating how prior AR flares may be unrelated to SEP-associated flares.