Solar Physics

, Volume 252, Issue 1, pp 121–137 | Cite as

Multiresolution Analysis of Active Region Magnetic Structure and its Correlation with the Mount Wilson Classification and Flaring Activity

  • J. Ireland
  • C. A. Young
  • R. T. J. McAteer
  • C. Whelan
  • R. J. Hewett
  • P. T. Gallagher


Two different multiresolution analyses are used to decompose the structure of active-region magnetic flux into concentrations of different size scales. Lines separating these opposite polarity regions of flux at each size scale are found. These lines are used as a mask on a map of the magnetic field gradient to sample the local gradient between opposite polarity regions of given scale sizes. It is shown that the maximum, average, and standard deviation of the magnetic flux gradient for α,β,β γ, and β γ δ active-regions increase in the order listed, and that the order is maintained over all length scales. Since magnetic flux gradient is strongly linked to active-region activity, such as flares, this study demonstrates that, on average, the Mt. Wilson classification encodes the notion of activity over all length scales in the active-region, and not just those length scales at which the strongest flux gradients are found. Further, it is also shown that the average gradients in the field, and the average length-scale at which they occur, also increase in the same order. Finally, there are significant differences in the gradient distribution, between flaring and non-flaring active regions, which are maintained over all length scales. It is also shown that the average gradient content of active-regions that have large flares (GOES class “M” and above) is larger than that for active regions containing flares of all flare sizes; this difference is also maintained at all length scales. All of the reported results are independent of the multiresolution transform used. The implications for the Mt. Wilson classification of active-regions in relation to the multiresolution gradient content and flaring activity are discussed.


Sun: active region Sun: magnetic field 


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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • J. Ireland
    • 1
  • C. A. Young
    • 1
  • R. T. J. McAteer
    • 2
  • C. Whelan
    • 3
  • R. J. Hewett
    • 4
  • P. T. Gallagher
    • 5
  1. 1.ADNET Systems, Inc., NASA’s Goddard Spaceflight CenterGreenbeltUSA
  2. 2.Catholic University of America, NASA Goddard Space Flight CenterGreenbeltUSA
  3. 3.School of PhysicsUniversity College DublinDublin 4Ireland
  4. 4.Computer Science DepartmentUniversity of Illinois at Urbana-ChampaignUrbanaUSA
  5. 5.Astrophysics Research Group, School of PhysicsTrinity College DublinDublin 2Ireland

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