A multi-wavelength approach to solar energetic particle transport using remote sensing and in-situ observations

Abstract

Space weather (SWx) studies and the development of SWx prediction models have gained significant momentum in the last few years. Large SWx events have the potential to incapacitate technological infrastructure, both on the surface and in orbit around the Earth. The risk of radiation exposure for astronauts during a SWx event can also not be ignored. This study investigates the broad range of indirect solar energetic particle (SEP) observations across the electromagnetic spectrum and their association with SWx events. The study starts at the lower energy radio waves, including coronal type II and III radio bursts, and progresses to the higher energy end of the spectrum, including solar X-rays and solar gamma rays. The two-dimensional (2D) SEP transport model of Strauss and Fichtner [2015] is presented, together with a parameter study. Gaussian curves are fitted to the modelling results and show that the influences of perpendicular diffusion and the broadness of the initial injection region can be separated if SEP observations are made closer to the Sun. Simulation results of proton propagation are also shown. A SWx prediction model, based on the Neupert effect, is presented and found to be a convenient way to predict the presence of hard X-rays (HXRs) without directly observing them, but rather exploiting the causal relationship between soft X-rays (SXRs) and HXRs. The SXRs are used as an injection proxy in the aforementioned transport model [Steyn et al., 2020]. The numerical heliospheric magnetic field (HMF) of Li et al. [2016] is implemented in the SEP transport model of Strauss and Fichtner [2015]. The particle intensity distributions show a rippled peak distribution in contrast to the Gaussian-like distribution when a standard Parker HMF geometry is assumed. This is attributed to the large scale meandering magnetic field lines that can lead to the mixing of empty and energetic particle filled magnetic flux tubes since some flux tubes may not be well connected to the injection region. The progress and initial observations from the North-West University (NWU) solar telescope project are also presented.