Abstract
Abstract Global EUV waves remain a controversial phenomenon more than 20 yr after their discovery by SOHO/EIT. Although consensus is growing in the community that they are most likely large-amplitude waves or shocks, the wide variety of observations and techniques used to identify and analyze them have led to disagreements regarding their physical properties and interpretation. Here, we use a 3D magnetohydrodynamic (MHD) model of the solar corona to simulate an EUV wave event on 2009 February 13 to enable a detailed validation of the various commonly used detection and analysis techniques of global EUV waves. The simulated event exhibits comparable behavior to that of a real EUV wave event, with similar kinematic behavior and plasma parameter evolution. The kinematics of the wave are estimated via visual identification and profile analysis, with both approaches providing comparable results. We find that projection effects can affect the derived kinematics of the wave, due to the variation in fast-mode wave speed with height in the corona. Coronal seismology techniques typically used for estimates of the coronal magnetic field are also tested and found to estimate fast-mode speeds comparable to those of the model. Plasma density and temperature variations of the wave front are also derived using a regularized inversion approach and found to be consistent with observed wave events. These results indicate that global waves are best interpreted as large-amplitude waves and that they can be used to probe the coronal medium using well-defined analysis techniques.
Highlights
Ever since their discovery by Dere et al (1997), Moses et al (1997), and Thompson et al (1998) using the Extreme ultraviolet Imaging Telescope (EIT; Delaboudinière et al 1995) on board the Solar and Heliosphere Observatory (SOHO; Domingo et al 1995), global waves in the low solar corona have been systematically observed using Extreme UltraViolet (EUV) passbands
Called “EIT waves”, these phenomena have since been observed in the EUV using the Extreme UltraViolet Imager (EUVI; Wuelser et al 2004) on board the Solar Terrestrial Relations Observatory (STEREO; Kaiser et al 2008) and more recently by the Atmospheric Imaging Assembly (AIA; Lemen et al 2012) on board the Solar Dynamics Observatory (SDO; Pesnell et al 2012), the Sun Watcher with Active Pixels and Image Processing (SWAP; Seaton et al 2013) on board the Project for On-Board Autonomy 2 satellite (PROBA2; Santandrea et al 2013), and the Solar Ultraviolet Imager (SUVI; Seaton & Darnel 2018) on board the GOES-16 spacecraft
We have considered only the time interval in which wave fronts were detected in the actual observations, and we have selected synthesized frames according to the cadence of EUVI
Summary
Ever since their discovery by Dere et al (1997), Moses et al (1997), and Thompson et al (1998) using the Extreme ultraviolet Imaging Telescope (EIT; Delaboudinière et al 1995) on board the Solar and Heliosphere Observatory (SOHO; Domingo et al 1995), global waves in the low solar corona have been systematically observed using Extreme UltraViolet (EUV) passbands. With the advent of SDO/AIA this issue has been greatly diminished, a myriad of techniques and approaches are still used to identify and characterize these features across a wide range of passbands observing plasma at different temperatures As they propagate through the low solar corona, global EUV waves potentially provide an opportunity to probe properties of the low solar atmosphere that remain frustratingly out of reach of current instrumentation. Interpretation of these features as MHD waves offers the opportunity to estimate the coronal magnetic field using coronal seismology techniques (see, e.g., Ballai 2007; West et al 2011; Kwon et al 2013; Long et al 2013, for previous work done on this topic) They are closely associated with coronal mass ejections (CMEs) and can potentially provide insight into the direction and extent of the initial eruption (e.g., Temmer et al 2011; Möstl et al 2015; Long et al 2019).
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