Forecasting solar proton events by using the ESPERTA model

The ESPERTA (Empirical model for Solar Proton Event Real Time Alert) forecast tool has a Probability of Detection (POD) of 63% for all >10 MeV events with proton peak intensity ≥10 pfu (i.e., ≥S1 events, S1 referring to minor storms on the NOAA Solar Radiation Storms scale), from 1995 to 2014 with a false alarm rate (FAR) of 38% and a median (minimum) warning time (WT) of ∼4.8 (∼0.4) hr. The ESPERTA model modified to predict ≥S2 (i.e., ≥100 pfu) has a POD of 75% and a FAR of 24% for the 1995 - 2014 interval with a median (minimum) WT of ∼1.7 (∼0.2) hr based on predictions made at the time of the S1 threshold crossing. Here, both versions of the ESPERTA model have been applied to forecast recent solar proton events from 2015 to 2017, yielding results consistent with model performance for the 1995 to 2014 interval.