Simulations of radio-wave anisotropic scattering to interpret type III radio bursts measurements by Solar Orbiter, Parker Solar Probe, STEREO and Wind

TL;DR

This study combines multi-spacecraft observations and ray-tracing simulations to analyze the directivity and anisotropic scattering of type III solar radio bursts, revealing event-to-event variability in directivity patterns.

Contribution

It introduces a method to estimate radio source positions and directivity using simultaneous multi-spacecraft data and compares these observations with anisotropic scattering simulations.

Findings

Directivity patterns vary between events.

Simultaneous observations enable source localization.

Anisotropic scattering explains directivity shape variations.

Abstract

We use multi-spacecraft observations of invididual type III radio bursts in order to calculate the directivity of the radio emission, to be compared to the results of ray-tracing simulations of the radio-wave propagation and probe the plasma properties of the inner heliosphere. Ray-tracing simulations of radio-wave propagation with anisotropic scattering on density inhomogeneities are used to study the directivity of radio emissions. Simultaneous observations of type III radio bursts by four widely-separated spacecraft are used to calculate the directivity and position of the radio sources. The shape of the directivity pattern deduced for individual events is compared to the directivity pattern resulting from the ray-tracing simulations. We show that simultaneous observations of type radio III bursts by 4 different probes provide the opportunity to estimate the radio source positions and the directivity of the radio emission. The shape of the directivity varies from one event to another, and is consistent with anisotropic scattering of the radio-waves.