Pre-Flare Dynamics of Sunspot Groups

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.

References in corpus (3)

• Driving major solar flares and eruptions: a review
• Magnetic Field Structures Triggering Solar Flares and Coronal Mass Ejections
• The energy of high frequency waves in the low solar Chromosphere

Cited by in corpus (12)

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• The characteristics of flare- and CME-productive solar active regions
• Properties of Flare-Imminent versus Flare-Quiet Active Regions from the Chromosphere through the Corona I: Introduction of the AIA Active Region Patches (AARPs)
• Dynamic Precursors of Flares in Active Region NOAA 10486
• A New Approach to Solar Flare Prediction
• Features of Microwave Radiation and Magnetographic Characteristics of Solar Active Region NOAA 12242 Before the X1.8 Flare on December 20, 2014