Solar Radiation Storms: observational analysis and numerical modelling of solar energetic particle events
Author: Daniel Pacheco
Abstract: Solar Energetic Particles (SEPs) events consist of ions (mainly protons) and electrons accelerated by solar eruptive events such as flares and shocks associated with coronal mass ejections (CMEs). SEPs travel along the interplanetary magnetic field and are detected by spacecraft in the heliosphere, with energies from few keV to tens of GeV for ions and hundreds of MeV for electrons. We study the properties of SEP events in terms of intensity, onset time, duration, peak intensity, and fluence. For that purpose, we make use of several in-situ measurements made by different satellites, like STEREO A-B, ACE, SOHO and, HeliosELIOS I-II, etc. In addition, we study remote measurements of electromagnetic emissions from the Sun (in white light, radio and X-rays) associated with the parent solar eruptions. Numerical models help us characterise both the propagation of the particles in interplanetary space and the timescales of their release processes. We use the SEPinversion tool to fit the intensity-time profiles measured in different fields of view during solar near-relativistic electronSEP events. This model permits us to infer the particle injection profile at the Sun and estimate the electron mean free path. We present the results we obtained for the 2014 August 1 electron event as an example.
On the other hand, our group has developed a tool, named SOLPENCO2, that provides synthetic proton intensity-time profiles of large SEP events for virtual observers at different heliocentric distances from the Sun (from 0.2 AU up to 1.6 AU). The results derived from SOLPENCO2, are used in a SEP statistical model to estimate the proton radiation environment for interplanetary missions (http://dev.sepem.oma.be). Here we present recent updates to SOLPENCO2 and discuss their impact in the SEP statistical model.