HR: 0830h
AN: SP41B-04    [Abstracts]
TI: Multi-scale analysis of solar structures: flatness functions of magnetograms
AU: * Abramenko, V
EM: avi@bbso.njit.edu
AF: Big Bear Solar Observatory of NJIT, 40386 North Shore Lane, Big Bear City, CA 92314 United States
AU: Romano, P
EM: prom@ct.astro.it
AF: Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 78, Catania, 95125 Italy
AB: The fine small-scale structure of the solar surface becomes more pronounced as the observational techniques improve. Complex filigree structures of solar granulation, sunspots, photospheric magnetic and velocity fields can not be described adequately by a single parameter (e.g., filling factor, fractal dimension, or power law index, etc.). Methods which incorporate parameters that are a function of scale (multi-scale methods) to describe the complexity of a field under study should be involved. The multifractal approach offers such a possibility. Multifractality can manifest itself through the shape of a flatness function defined as a ratio of the sixth structure function to the cube of the second structure function (Frisch 1995). For monofractal structures, the flatness is constant with a scale, whereas for multifractal structures the flatness grows as a power-law when the scale decreases. Calculating the flatness functions for SOHO/ MDI high resolution magnetograms of active regions from the catalog available at http://www.bbso.njit.edu/~avi/MDI_catalog.htm we found that the flatness function is unique for each active region. The power-law index, as well as the range of the flatness growth (the scale interval of multifractality), vary for different active regions that indicates the difference in mutlifractality. We found that flare-quiet active regions tend to possess lower degree of multifractality than flaring active regions do. The increase in multifractality is a signal that a magnetic structure is driven to a critical state, thus gaining tangential discontinuities of various length scales. The above suggestion about the relation between the degree of multifractality and level of flare productivity seems to be reasonable and deserves further investigations.
UR: http://www.bbso.njit.edu/~avi/
DE: 3250 Fractals and multifractals
DE: 7519 Flares
DE: 7524 Magnetic fields
DE: 7529 Photosphere
DE: 7839 Nonlinear phenomena
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly