Comparison of solar energetic electron events between solar cycle 23 and 24

Solar energetic electron events are the most common solar particle acceleration phenomenon observed in the interplanetary medium. Here we present a statistical comparison of solar energetic electron events observed by WIND/3DP and their association with other solar phenomena, between solar cycle 23 and 24. In solar cycle 23 (24), the event occurrence rate of solar energetic electrons is 12/year (6/year) at solar minimum and ~160-190/year (~150 /year) around solar maximum. In solar cycle 24, relatively more (~80% vs. ~60%) electron events are detected at energies down to <5 keV, but less (~40% vs. 60%) events are at energies up to >100 keV, suggesting a less efficient particle acceleration at the Sun, compared to solar cycle 23. In solar cycle 23, the monthly occurrence rate of solar electron events is barely (0.24) correlated with sunspots, while in solar cycle 24, the event monthly occurrence rate is moderately (0.58) correlated with sunspots at solar minimum. In both cycles, solar electron events have a poor (~0.35) association with GOES soft X-ray fares. Finally, we will also discuss the association of solar electron events with active regions and coronal mass ejections.