Fredagskollokvium: Solar Energetic Particle events: Modelling and Prediction
Angels Aran-Sensat, University of Barcelona
Specially since the last decade, many efforts working towards developing an infrastructure for the monitoring and prediction of space weather have been invested in Europe. This includes the study of solar energetic particle (SEP) events, with the ultimate goal of predicting both the particle radiation in the interplanetary space and at near-Earth environment. The most important contribution to radiation doses comes from protons > 10 MeV, although ions > 1 MeV/nuc may traverse typical shielding. About 100 SEP events with > 10 MeV protons are produced per solar cycle, and < 10 large events occur with fluences accounting for a significant fraction of the solar cycle's accumulated fluence.
Solar activity producing SEP events are mainly coronal mass ejections (CMEs) and flares, being the former the main sources in large events. Three-dimensional magnetohydrodynamic models describing the propagation of interplanetary (IP) shocks driven by CMEs are routinely run to estimate IP shocks arrivals at Earth. The combination of such models with SEP models of particle acceleration and transport is a hot topic in heliophysics and it is the necessary step to be undertaken for the forecasting of large SEP events in near-real time. The main difficulty is that the current knowledge of the mechanisms involved in the generation of these SEP events is not complete yet, rendering the prediction of individual SEP events difficult. However, first attempts are currently being developed. In addition to the models describing SEP events episodes, particle radiation models are used to estimate the accumulated fluence, maximum intensity and worse case scenarios that interplanetary missions may encounter during their orbits. These models are based on the statistical treatment of SEP data measured during the last 40 years, and they make assumptions on the variation of the SEP event size with the heliocentric radial distance from the Sun.
We present here the SEP models and prediction tools being developed in the Heliospheric Physics and Space Weather Group of the Universisty of Barcelona in collaboration with different European groups.