Intermittency in the photosphere and corona above an active region

TL;DR

This study investigates the temporal relationship of intermittency in the photosphere, chromosphere, and corona of an active region, revealing a sequence where photospheric intermittency peaks before coronal activity and solar flares.

Contribution

It provides the first detailed analysis of simultaneous intermittency variations across multiple solar atmospheric layers in an active region.

Findings

Photospheric intermittency peaks after maximum plasma flow vorticity.

Coronal intermittency increases gradually following photospheric changes.

The delay between photospheric intermittency peak and a major flare is approximately 1.3 days.

Abstract

Recent studies undoubtedly demonstrate that the magnetic field in the photosphere and corona is an intermittent structure, which offers new views on the underlying physics. In particular, such problems as the existence in the corona of localized areas with extremely strong resistivity (required to explain magnetic reconnection of all scales) and the interchange between small and large scales (required in study of the photosphere/corona coupling), to name a few, can be easily captured by the concept of intermittency. This study is focused on simultaneous time variations of intermittency properties derived in the photosphere, chromosphere and corona. We analyzed data for NOAA AR 10930 acquired between Dec 08, 2006 12:00 UT and Dec 13, 2006 18:45 UT. Photospheric intermittency was inferred from Hinode magnetic field measurements, while intermittency in the transition region and corona was derived from Nobeyama 9 GHz radio polarization measurements, high cadence Hinode/XRT/Be-thin data as well as GOES 1-8\AA flux. Photospheric dynamics and its possible relationship with the intermittency variations were also analyzed by calculating the kinetic vorticity. For this case study we found the following chain of events. Intermittency of the photospheric magnetic field peaked after the specific kinetic vorticity of plasma flows in the AR reached its maximum level (4 hour time delay). In turn, gradual increase of coronal intermittency occurred after the peak of the photospheric intermittency. The time delay between the peak of photospheric intermittency and the occurrence of the first strong (X3.4) flare was approximately 1.3 days. Our analysis seems to suggest that the enhancement of intermittency/complexity first occurs in the photosphere and is later transported toward the corona.