Ildv. Space Res. Vol.4, No.10, pp.165—172, 1984 0273—1177/84 $0.00 + .50 Printed in Great Britain. All rights reserved, Copyright © COSPAR THE MONITORING AND PREDICTION OF SOLAR PARTICLE EVENTS — AN EXPERIENCE REPORT G. Heckman, J. Hirman, J. Kunches and C. Baich Space Environment Services Center, R/E/5E2, National Oceanic and Atmospheric Administration, 325 Broadway, Boulder, CO 80303, U.S.A. ABS~AC~ The routine monitoring and prediction of solar proton events that may be a hazard to personnel and materials in space are a routine service of the Space Environment Services Center in Boulder, Co].oradm, U.S.A. The services provided are made available to the space centers in the United States for use in their operations. The real tine monitoring consists primarily of Space Environment Monitors on both geosynchronous and polar orbiting weather satellites. The monitoring emphasizes proton fluxes but alpha particles, electrons, and in one case, heavier particles, are included. The predictions are of two types; a general outlook made 1 to 3 days in advance, and specific prediction of event size and probability of occurrence made after a solar flare occurs. The accuracy of the predictions made for solar cycle 21 are assessed. INI~JC~I0N The Space Environment Services Center (SESC), a joint operation of the National Oceanic and Atmospheric Administration and the U.S. Air Force, is the United States center for monitoring and predicting disturbances in the solar terrestrial environment. Included in these services are predictions, alerts and summaries of the occurrence of solar particle events — — increases in the fluxes of energetic particles that originate in solar activity and which pose a radiation hazard for personnel on space flights. The services provided during solar cycle 21 (beginning in early 1976) are a general service, oriented to all users who are affected by solar proton events. The predictions are heavily weighted toward protons with energies 10 MeV and greater. By contrast, the prediction services offered during solar cycle 20 were weighted toward particles with energies of 30 MeV and greater. !‘DNflORfl~ The real time monitoring system used by the SESC is based on monitoring satellites in both geosynchronous and polar orbits. The geosynchronous orbits are advantageous for the case of continuous tracking and constant read-out. The polar orbiting sensors will provide actual polar cap fluxes when regular space flights begin in polar orbit. For protons with energies above 20 MeV, there is little difference in the observed fluxes in the two orbits. For energies of 5 to 20 MeV, the differences may become substantial because of shielding effects of the outer magnetosphere. The monitoring sensors operated by the SESC are a part of the Space Environment Monitors (SEM) flown on the GOES (Geosynchronous Orbiting Earth Satellite) and the t’~Aweather satellites. The coverage of the energetic particle monitors are summarized in table 1 /1,2/. ~BLE 1 Real Time Monitoring Coverage of Solar Energetic Particles Alpha Protons Particles Particles Electrons of 2 > 2 GOES 0.8—1000 MeV 7—1000 MeV — >2 14ev (Synchronous Orbit) 30 key — 6—55 14eV 30—> 300 key 165