Abstract
AbstractSolar Stormwatch was the first space weather citizen science project, the aim of which is to identify and track coronal mass ejections (CMEs) observed by the Heliospheric Imagers aboard the STEREO satellites. The project has now been running for approximately 4 years, with input from >16,000 citizen scientists, resulting in a data set of >38,000time‐elongation profiles of CME trajectories, observed over 18 preselected position angles. We present our method for reducing this data set into a CME catalogue. The resulting catalogue consists of 144 CMEs over the period January 2007 to February 2010, of which 110 were observed by STEREO‐A and 77 were observed by STEREO‐B. For each CME, the time‐elongation profiles generated by the citizen scientists are averaged into a consensus profile along each position angle that the event was tracked. We consider this catalogue to be unique, being at present the only citizen science‐generated CME catalogue, tracking CMEs over an elongation range of 4° out to a maximum of approximately 70°. Using single spacecraft fitting techniques, we estimate the speed, direction, solar source region, and latitudinal width of each CME. This shows that at present, the Solar Stormwatch catalogue (which covers only solar minimum years) contains almost exclusively slow CMEs, with a mean speed of approximately 350 km s−1. The full catalogue is available for public access at www.met.reading.ac.uk/~spate/solarstormwatch. This includes, for each event, the unprocessed time‐elongation profiles generated by Solar Stormwatch, the consensus time‐elongation profiles, and a set of summary plots, as well as the estimated CME properties.
Highlights
Coronal mass ejections (CMEs) are eruptions of predominantly coronal plasma and magnetic flux out into the heliosphere [e.g., Webb and Howard, 2012] and are widely recognized as a key driver of space weather [Hapgood, 2011; Cannon et al, 2013]
Imaging the coronal mass ejections (CMEs) Fronts So far, we have considered the evolution of an event as represented by a cluster of t-ε profiles over multiple position angles (PA), but it has not yet been demonstrated that this methodology can accurately capture the shape of the CME fronts that have been visually identified in the Heliospheric Imagers (HI) images
This study has detailed the construction of a catalogue of CMEs observed in HI images from STA and STB, made possible by the large database of CME t-ε profiles generated by the Solar Stormwatch citizen science project, in particular the Trace-it! activity
Summary
Coronal mass ejections (CMEs) are eruptions of predominantly coronal plasma and magnetic flux out into the heliosphere [e.g., Webb and Howard, 2012] and are widely recognized as a key driver of space weather [Hapgood, 2011; Cannon et al, 2013]. Modern remote sensing observations consist primarily of white-light coronagraph images, such as those taken by the Large Angle Spectroscopic Coronagraph (LASCO) on the SOHO satellite [Brueckner et al, 1995], the COR Lyot coronagraphs on the twin STEREO satellites [Howard et al, 2008], and wide-angle Heliospheric Imagers, such as the Solar Mass Ejection Imager (SMEI) on the Coriolis satellite [Webb et al, 2006] and the Heliospheric Imagers (HI) on the STEREO satellites [Eyles et al, 2008] Many of these observations are complimentary as they cover different regions of the solar corona and inner heliosphere and span different periods of time.
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