Probabilistic space weather forecast of the relativistic electron flux enhancement at geosynchronous orbit

An operational technique has been developed for a probabilistic space weather forecast of relativistic electrons at geosynchronous orbit, following a concept of a daily precipitation probabilistic weather forecast. In this paper, we use the arrival time of stream interfaces as a precursor of corotating interaction regions to make the probability diagram for flux enhancement of relativistic electrons at geosynchronous orbit, and the probability is defined by the number of events with the daily maximum flux above the NOAA alert levels. The probability diagram associated with the stream interfaces is constructed to achieve an efficient probabilistic forecast, based on the two fundamental parameters of oncoming streams; whether the solar wind speed is higher than average (500 km/s) or not, and which sector polarities the interplanetary magnetic field belongs to, according to the so-called “Spring-Toward Fall-Away” rule.