CMEs and SEPs During November-December 2020: A Challenge for Real-Time Space Weather Forecasting

TL;DR

This study evaluates the accuracy of real-time space weather forecasts of CMEs and SEPs during late 2020, using multi-point observations and modeling to test prediction capabilities across the inner heliosphere.

Contribution

It demonstrates the potential of current modeling tools to predict CMEs and SEPs at multiple heliospheric locations beyond Earth, incorporating multi-point remote sensing data.

Findings

Forecasts are reasonably accurate several tens of degrees from eruption sites.

Multi-point observations improve validation of space weather models.

Limitations exist due to model assumptions and architecture.

Abstract

Predictions of coronal mass ejections (CMEs) and solar energetic particles (SEPs) are a central issue in space weather forecasting. In recent years, interest in space weather predictions has expanded to include impacts at other planets beyond Earth as well as spacecraft scattered throughout the heliosphere. In this sense, the scope of space weather science now encompasses the whole heliospheric system, and multi-point measurements of solar transients can provide useful insights and validations for prediction models. In this work, we aim to analyse the whole inner heliospheric context between two eruptive flares that took place in late 2020, i.e. the M4.4 flare of November 29 and the C7.4 flare of December 7. This period is especially interesting because the STEREO-A spacecraft was located ~60{\deg} east of the Sun-Earth line, giving us the opportunity to test the capabilities of "predictions at 360{\deg}" using remote-sensing observations from the Lagrange L1 and L5 points as input. We simulate the CMEs that were ejected during our period of interest and the SEPs accelerated by their shocks using the WSA-Enlil-SEPMOD modelling chain and four sets of input parameters, forming a "mini-ensemble". We validate our results using in-situ observations at six locations, including Earth and Mars. We find that, despite some limitations arising from the models' architecture and assumptions, CMEs and shock-accelerated SEPs can be reasonably studied and forecast in real time at least out to several tens of degrees away from the eruption site using the prediction tools employed here.