Solar Proton Events Long-term Forecasting Model

Solar energetic particle events can cause major disruptions to the operation of spacecraft in earth orbit and outside the earth's magnetosphere, and they may also have an effect on radiation doses received by the crew flying in high altitude aircraft over the Polar Regions. Establishing prediction model for total fluence of solar protons accumulated during a mission and taking protective measures are of vital significance for the safety of the spacecraft and astronaut. For the solar proton event caused by solar eruption, the understanding and forecast research were summarized in this paper. The occurrence mechanism, spreading process as well as the hazard brought by bad space radiation environment were all discussed.It is derived from the set of data collected by the IMP and GOES spacecraft between 1964 and 2007 in this paper. Based on a data set of proton events from the last four solar cycles, we described a predictive engineering model for the interplanetary fluence of protons with energies >1, >10, >30, >60MeV. Because of the quasi-random nature of the occurrences, fluence, and spectra of solar proton events, solar proton mission fluences must be treated statistically. The purpose of this analysis is to derive the probability of exceeding various proton fluences as a function of fluence, proton energy, and mission duration. Compared to commonly used JPL model, solar activity levels is taken into account to get the occurrence probability of proton events. The new model can access proton fluences in different phase, and is more according with the distribution of proton events.