Wednesday

Remote sensing of coronal and heliospheric periodicities can provide vital insight into local conditions and dynamics of the solar atmosphere.
Our investigation seeks to trace long (1hr or longer) periodic signatures (previously identified above the limb in the corona in e.g. Telloni et al., 2013) from their origin at the solar surface out into the heliosphere. To do this, we combine on-disk measurements taken by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) and concurrent extreme ultra-violet (EUV) and coronagraph data from several instruments on-board one of the Solar Terrestrial Relations Observatory (STEREO) spacecraft. We target two active regions near an equatorial coronal hole, seen over several days in early 2011, on disk and above the solar limb at the same time. Fourier and wavelet analysis of signals are performed (with and without detrending the original time-series). Typical spectral power densities vary by several orders of magnitude as a function of period, indicating red (rather than white) noise dominated spectra.
Applying uniform confidence levels above detrended spectra yields detections of oscillatory signatures, aligned with local magnetic structures, with 6-13hr periods in both AIA and STEREO instruments (filtering out periods longer than 15hrs). Applying global confidence levels (Auchere et al., 2016) based on a red and white background noise model without detrending instead uncovers sporadic, spatially uncorrelated evidence of periodic signatures in either instrument.
In this presentation, we will compare and contrast our findings and discuss the merits and applicability of both methods of confidence level calculation.