Tracking CMEs using data from the Solar Stormwatch project; observing deflections and other properties

Shannon R Jones,Christopher J Scott,Luke A Barnard,Julia Wilkinson,Mathew J Owens

doi:10.1002/2017sw001640

Abstract

AbstractWith increasing technological dependence, society is becoming ever more affected by changes in the near‐Earth space environment caused by space weather. The primary driver of these hazards are coronal mass ejections (CMEs). Solar Stormwatch is a citizen science project in which volunteers participated in several activities which characterized CMEs in the remote sensing images from the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument package on the twin STEREO spacecraft. Here we analyze the results of the “Track‐it‐back” activity, in which CMEs were tracked back through the COR1, COR2, and EUVI images. Analysis of the COR1, COR2, and EUVI data together allows CMEs to be studied consistently throughout the whole field of view spanned by these instruments (out to 15 RS). A total of 4783 volunteers took part in this activity, creating a data set containing 23,801 estimates of CME timing, location, and size. We used these data to produce a catalogue of 41 CMEs, which is the first to consistently track CMEs through each of these instruments. We assess how the CME speeds, propagation directions, and widths vary as the CMEs propagate through the fields of view of the different imagers. In particular, we compare the observed CME deflections between the COR1 and COR2 fields of view to the separation between the CME source region and the heliospheric current sheet (HCS), demonstrating that in general, these CMEs appear to deflect toward the HCS, consistent with other modeling studies of CME propagation.

Highlights

Coronal mass ejections (CMEs) are eruptions of plasma from the Sun which propagate radially outward into the heliosphere [Gopalswamy et al, 2009]
We demonstrate that coronal mass ejections (CMEs) tend to accelerate, increase in width, and deflect toward the heliospheric current sheet as they propagate through the combined extreme ultraviolet imager (EUVI), COR1, and COR2 fields of view
This paper explored a data set from the Solar Stormwatch Track-it-back activity, covering the time period from 28 February 2007 to 12 February 2010

Summary

Introduction

Coronal mass ejections (CMEs) are eruptions of plasma from the Sun which propagate radially outward into the heliosphere [Gopalswamy et al, 2009]. Possible consequences of extreme space weather were recently discussed in a report by Cannon et al [2013] and include damage and degradation of transformer cores in the electricity grid, loss of high-frequency radio communications, and anomalies in satellites from increased surface and internal charging. Observations of the Sun are made using various different space-based and ground-based instrumentation packages. These include, but are not limited to, extreme ultraviolet imagers, coronagraphs, and heliospheric imagers, which have been widely used to study CME initiation and evolution.

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Conclusion