An Early Warning Prediction Scheme for Solar Proton Events

Solar proton events (SPEs) are preceded by the optical, radio, and X-ray emissions of solar flares. Thus the capability for providing early warning of SPEs is possible if the particle fluxes can be correlated with the electromagnetic signatures from the sun. We have developed and refined the correlations of the peak proton flux at geosynchronous orbit with the solar X-ray emissions using data collected by the GOES spacecraft and supplied by NOAA. We have used data from over most of solar cycle 21 and the early portion of cycle 22 to extend the data base and improve the correlations. A power law relationship has been assumed between the peak proton flux and the X-ray fluence in both the 0.5-4 and 1-8 Angstrom bands of the GOES X-ray sensors. The correlation coefficients are approximately the same for both X-ray energy bands. We have also examined and obtained the correlation between the X-ray energy and peak proton flux at different proton energies. The correlation becomes better as the energy of the protons increases.