A Coherence-Based Approach for Tracking Waves in the Solar Corona

Abstract

We consider the problem of automatically (and robustly) isolating and extracting information about waves and oscillations observed in EUV image sequences of the solar corona with a view to near real-time application to data from the Atmospheric Imaging Array (AIA) on the Solar Dynamics Observatory (SDO). We find that a simple coherence / travel-time based approach detects and provides a wealth of information on transverse and longitudinal wave phenomena in the test sequences provided by the Transition Region and Coronal Explorer (TRACE). The results of the search are pruned (based on diagnostic errors) to minimize false-detections such that the remainder provides robust measurements of waves in the solar corona, with the calculated propagation speed allowing automated distinction between various wave modes. In this paper we discuss the technique, present results on the TRACE test sequences, and describe how our method can be used to automatically process the enormous flow of data (≈1Tb/day) that will be provided by SDO/AIA after launch in late 2008. Since the launch of the Transition Region and Coronal Explorer (TRACE; Handy et al. 1999) the community has invested a great deal of effort on the identification and analysis of longitudinal and transverse wave phenomena in loop structures seen in its EUV images of the corona (see Nakariakov and Verwichte 2005, for a good overview). The great interest in finding and characterizing coronal waves is driven by the promise of coronal seismology which could lead to the determination of otherwise inaccessible physical properties of the solar atmosphere by studying phase speeds, amplitudes, dissipation, etc. of the observed waves (Nakariakov and Verwichte 2005). There are many unresolved issues in coronal seismology: for example, it is unclear why only a subset of coronal loops show transverse oscillations in the wake of a flare or CME (e.g.,

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Cite this paper

@inproceedings{McIntosh2008ACA, title={A Coherence-Based Approach for Tracking Waves in the Solar Corona}, author={Scott W McIntosh and Steven Tomczyk}, year={2008} }