Comparison of the Scaling Properties of EUV Intensity Fluctuations in Coronal Hole and Quiet-Sun Regions

Comparison of the Scaling Properties of EUV Intensity Fluctuations in Coronal Hole and Quiet-Sun RegionsCadavid, Ana CristinaMiralles, Mari PazRomich, KristineDOI: info:10.3847/1538-4357/ab4d4ev. 886143
Cadavid, Ana Cristina, Miralles, Mari Paz, and Romich, Kristine. 2019. "Comparison of the Scaling Properties of EUV Intensity Fluctuations in Coronal Hole and Quiet-Sun Regions." The Astrophysical Journal 886:143. https://doi.org/10.3847/1538-4357/ab4d4e
ID: 154514
Type: article
Authors: Cadavid, Ana Cristina; Miralles, Mari Paz; Romich, Kristine
Abstract: Using detrended fluctuation analysis and rescaled range analysis, we investigate the scaling properties of extreme ultraviolet (EUV) intensity fluctuations of low-latitude coronal holes (CHs) and neighboring quiet-Sun (QS) regions in signals obtained with the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly instrument. Contemporaneous line-of-sight SDO/Helioseismic and Magnetic Imager magnetic fields provide a context for the physical environment. We find that the intensity fluctuations in the time series of EUV images present at each spatial point a scaling symmetry over the range ∼20 minute to ∼1 hr. Thus we are able to calculate a generalized Hurst exponent and produce image maps, not of physical quantities like intensity or temperature, but of a single dynamical parameter that sums up the statistical nature of the intensity fluctuations at each pixel. In QS regions and in CHs with magnetic bipoles, the scaling exponent (1.0 &lt α ≤ 1.5) corresponds to anticorrelated turbulent-like processes. In CHs, and in QS regions primarily associated with (open) magnetic field of dominant polarity, the generalized exponent (0.5 < α < 1) corresponds to positively correlated (persistent) processes. We identify a tendency for α ∼ 1 near CH boundaries and in other regions in which open and closed magnetic fields are in proximity. This is a signature of an underlying 1/f type process that is characteristic for self-organized criticality and shot-noise models.