On the Brightness and Waiting-time Distributions of a Type III Radio Storm observed by STEREO/WAVES

TL;DR

This study analyzes the statistical properties of a Type III solar radio storm observed by STEREO/WAVES, revealing power-law brightness distribution and Poisson-like burst timing, suggesting independent burst events and avalanche-like activity.

Contribution

It presents the first analysis of the waiting-time distribution of Type III storms, showing independence of bursts and proposing an avalanche model for storm dynamics.

Findings

Brightness distribution follows a power law with index ~2.1

Waiting times are consistent with a Poisson process

Storm bursts occur independently, indicating avalanche behavior

Abstract

Type III solar radio storms, observed at frequencies below approximately 16 MHz by space borne radio experiments, correspond to the quasi-continuous, bursty emission of electron beams onto open field lines above active regions. The mechanisms by which a storm can persist in some cases for more than a solar rotation whilst exhibiting considerable radio activity are poorly understood. To address this issue, the statistical properties of a type III storm observed by the STEREO/WAVES radio experiment are presented, examining both the brightness distribution and (for the first time) the waiting-time distribution. Single power law behavior is observed in the number distribution as a function of brightness; the power law index is approximately 2.1 and is largely independent of frequency. The waiting-time distribution is found to be consistent with a piecewise-constant Poisson process. This indicates that during the storm individual type III bursts occur independently and suggests that the storm dynamics are consistent with avalanche type behavior in the underlying active region.