Multifractal Properties of Evolving Active Regions |
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| Authors: | P A Conlon P T Gallagher R T J McAteer J Ireland C A Young P Kestener R J Hewett K Maguire |
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| Institution: | (1) Astrophysics Research Group, School of Physics, Trinity College Dublin, Dublin, 2, Ireland;(2) Catholic University of America, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;(3) ADNET Systems Inc., NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;(4) DSM/DAPNIA/SEDI, CEA Saclay, Gif-sur-Yvette, France;(5) Computer Science Department, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA;(6) School of Physics, University College Dublin, Belfield, Dublin, 4, Ireland |
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| Abstract: | Magnetohydrodynamic turbulence is thought to be responsible for producing complex, multiscale magnetic field distributions
in solar active regions. Here we explore the multiscale properties of a number of evolving active regions using magnetograms
from the Michelson Doppler Imager (MDI) on the Solar and Heliospheric Observatory (SOHO). The multifractal spectrum was obtained by using a modified box-counting method to study the relationship between
magnetic-field multifractality and region evolution and activity. The initial emergence of each active region was found to
be accompanied by characteristic changes in the multifractal spectrum. Specifically, the range of multifractal structures
(D
div) was found to increase during emergence, as was their significance or support (C
div). Following this, a decrease in the range in multifractal structures occurred as the regions evolved to become large-scale,
coherent structures. From the small sample considered, evidence was found for a direct relationship between the multifractal
properties of the flaring regions and their flaring rate. |
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| Keywords: | Active regions Magnetic fields Turbulence |
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