Pre-Flare Dynamics of Sunspot Groups

TL;DR

This paper investigates sunspot group dynamics before solar flares, identifying characteristic magnetic gradient variations that could help predict flare occurrence and intensity within 8-10 hours.

Contribution

It introduces a novel proxy measure based on sunspot data to analyze pre-flare magnetic field gradients, providing potential early warning signatures.

Findings

Pre-flare magnetic gradient shows steep increase and high maximum.

Significant fluctuation and gradual decrease are observed before flares.

These properties can be used to assess flare probability and intensity.

Abstract

Several papers provide evidences that the most probable sites of flare onset are the regions of high horizontal magnetic field gradients in solar active regions. Besides the localization of flare producing areas the present work intends to reveal the characteristic temporal variations in these regions prior to flares. This study uses sunspot data instead of magnetograms, it follows the behaviour of a suitable defined proxy measure representing the horizontal magnetic field gradient. The source of the data is the SDD (SOHO/MDI-Debrecen Data) sunspot catalogue. The most promising pre-flare signatures are the following properties of the gradient variation: i) steep increase, ii) high maximum, iii) significant fluctuation and iv) a gradual decrease between the maximum and the flare onset which can be related to the "pull mode" of the current layer. These properties may yield a tool for the assessment of flare probability and intensity within the next 8-10 hours.