Modeling Polarized Radio Sounding Observations of a Coronal Mass Ejection

TL;DR

This paper presents analysis techniques for remote radio observations of Coronal Mass Ejections, evaluating their accuracy in measuring CME structure and speed using space-based instruments and simulations.

Contribution

It introduces the FETCH instrument concept and evaluates radio-based CME measurement methods with AWSoM simulations, highlighting their potential and limitations.

Findings

Faraday rotation may be more sensitive than TEC for CME structure detection.

In-situ measurements capture different aspects of CME properties.

Simulations reveal challenges in locating the CME trailing edge.

Abstract

Coronal Mass Ejections (CMEs) evolve significantly as they propagate from the Sun to the Earth, so remote observations of their changes in speed, strength of the magnetic field, density, and overall structure are critical for predicting their arrival time and geoeffectiveness. Radio line-of-sight observations of Faraday rotation and Total Electron Content combined with white-light observations enables the measurement of these properties with careful analyses. This paper describes the analysis techniques and evaluates their accuracy with regard to measuring a CME's complex evolving structure and speed. The approach utilizes the layout of the Faraday effect tracker of coronal and heliospheric structures (FETCH), a purely space-based instrument concept, with Alfven Wave Solar atmosphere Model (AWSoM) simulations as input for evaluating these radio-based measures. Focusing on density and velocity/speed, we find that in-situ measurements of CME properties observe similar but different aspects of the distinct CME structure. The AWSoM model suggests that Faraday rotation may be a more sensitive measure of structure than Total Electron Content (TEC). Finally, we discuss the difficulty the simulation reveals in determining the trailing edge location of a magnetic flux rope.