A Global Survey of EUV Coronal Power Spectra

We present results of an investigation of single-pixel intensity power spectra from a 12-hour time period on 26 June 2013 in a 1600 × 1600 -pixel region from four wavelength channels of NASA’s Solar Dynamics Observatory/Atmospheric Imaging Assembly . We extract single-pixel time series from derotated image sequences, fit two models as a function of frequency [ν] to their computed power spectra, and study the spatial dependence of the model parameters: i) a three-parameter power law + tail, Aν^-n+C , and ii) a power law + tail + three-parameter localized Lorentzian, Aν^-n + C + α/ (1 + (lnν-β)^2 /δ^2 ) , the latter to model periodicity. Spectra are well described by at least one of these models for all pixel locations, with the spatial distribution of best-fit model parameters shown to provide new and unique insights into turbulent, quiescent, and periodic features in the EUV corona and upper photosphere. Findings include the following: individual model parameters correspond clearly and directly to visible solar features; detection of numerous quasi-periodic three- and five-minute oscillations; observational identification of concentrated magnetic flux as regions of largest power-law indices [n] ; identification of sporadically located five-minute oscillations throughout the corona; detection of the known global ≈ -minute chromospheric oscillation; 2D spatial mapping of “coronal bullseyes” appearing as radially decaying periodicities over sunspots and sporadic foot-point regions, and of “penumbral periodic voids” appearing as broad rings around sunspots in 1600 and 1700 Å in which spectra contain no statistically significant periodic component.