Speaker
Description
Solar eruptive events can accelerate electrons that usually precede the arrival of the proton and ion components during solar energetic particle (SEP) events. These latter species have been much more studied in SEP radiation environment models than electrons. Solar energetic electron (SEE) populations are typically detected in the kinetic energy range from a few keV to a few MeV, with differential flux enhancements, above the background levels, of up to several orders of magnitude (depending on the instrument). SEE events are important for space weather safety considerations as they can have significant effects such as surface charging and surface erosion, particularly for interplanetary missions of long duration.
The study we present is embedded within the scope of the ESA’s FIRESPELL project. One of the objectives of this project is to extend the application of the SAPPHIRE-2S particle radiation model to electrons, in the energy range from 50 keV to 4 MeV, and for interplanetary missions travelling within 0.2 au to 10 au from the Sun.
By using data from IMP-8/CPME, ACE/EPAM and SOHO/COSTEP, a standardized dataset of electron events has been generated spanning from 1974 to 2017. From this dataset an event list of 401 electrons events was generated. Based on both the observed intensity-time profiles of the events at 1 au and the heliolongitude of the parent solar eruptive event, a quantitative classification system was used to divide the event list into 5 categories, each covering a statistically significant portion of the sample. From each category, up to two reference events were selected due to their archetypical constitution of the given class, with a total of 8 reference events. These reference events were modelled and fitted to the 1 au observational data using the particle transport model PARADISE as well as, in some cases, the MHD model EUHFORIA. Following the procedure developed during the SEPEM project (sepem.eu) and for the modelled events, we next derived the peak intensities and the event fluences for several observers located at other radial distances which share the same magnetic connection to the solar source as the near-Earth spacecraft.
We present the final results of this study, the parameters and simulations used for fitting observations as well as the resulting peak intensity and fluence heliocentric radial dependence for the studied range of electron energies; thus, offering insights into the SEEs transport in interplanetary space.
FIRESPELL is a project funded by ESA (Contract No. 4000142510/23/NL/CRS).
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