Identifying and Characterizing Radiation Belt Enhancement Events Across Three Solar Cycles

We introduce a new technique for identifying and characterizing radiation belt enhancement events based on statistical probability distributions. Techniques that use fixed thresholds to define an event cannot be easily generalized. In contrast, probability distributions allow, for example, direction comparison of GOES > 2 MeV integral flux with LANL 1.8-3.5 MeV differential flux or geosynchronous measurements with different L-shells. Here, we determine the criteria that define enhancement events that can be expected to occur once per month, once per year, or once per solar cycle. It is also interesting to start with an electron event and ask which geomagnetic or solar wind driving conditions are (or are not) related to those events. Probabilistic distributions allow us to define events based on radiation belt electron data alone, to classify types of enhancement events, and to ask: What conditions produced that class of events? How do event probabilities vary during the solar cycle? and How different is one cycle from another?