Category Archives: Publications

An analysis of magnetic reconnection events and their associated auroral enhancements

The article “An analysis of magnetic reconnection events and their associated auroral enhancements” was recently accepted to the American Geophysical Union (AGU) Journal of Geophysical Research: Space Science. The article, for which Nathan was the lead author, describes how small scale processes in the earth’s magnetotail, called magnetic reconnection, is associated with enhancements of the aurora.

Abstract

An analysis of simultaneous reconnection events in the near-Earth magnetotail and enhancements in the aurora is undertaken. Exploiting magnetospheric data from the Geotail, Cluster, and Double Star missions, along with auroral images from the IMAGE and Polar missions, the relationship between a reconnection signature and its auroral counterpart is explored. In this study of 59 suitable reconnection events, we find that 43 demonstrate a clear coincidence of reconnection and auroral enhancement. The magnetic local time (MLT) locations of these 43 reconnection events are generally located within ±1 h MLT of the associated auroral enhancement. A positive correlation coefficient of 0.8 between the two MLT locations is found. The enhancements are localized and short-lived (τ≤10 min) and are as likely to occur during the substorm process as in isolation of a substorm. No significant dependence of the reconnection or auroral enhancement location on the dusk-dawn components of the solar wind velocity (Vy), IMF (By) or local By or Vy, as measured by the reconnection-detecting spacecraft, is found.

The article is open source and free to download from the publisher’s site.

Determining the accuracy of crowdsourced tweet verification for auroral research

The article “Determining the accuracy of crowdsourced tweet verification for auroral research” was recently accepted to the journal Citizen Science: Theory and Practice. The article, for which Nathan was the lead author, describes the accuracy of citizen scientists at determining whether tweets relating to “aurora” were in fact sightings of the natural phenomenon.

Abstract

The Aurorasaurus project harnesses volunteer crowdsourcing to identify sightings of an aurora (the “northern/southern lights”) posted by citizen scientists on Twitter. Previous studies have demonstrated that aurora sightings can be mined from Twitter with the caveat that there is a large background level of non-sighting tweets, especially during periods of low auroral activity. Aurorasaurus attempts to mitigate this, and thus increase the quality of its Twitter sighting data, by using volunteers to sift through a pre-filtered list of geolocated tweets to verify real-time aurora sightings. In this study, the current implementation of this crowdsourced verification system, including the process of geolocating tweets, is described and its accuracy (which, overall, is found to be 68.4%) is determined. The findings suggest that citizen science volunteers are able to accurately filter out unrelated, spam-like, Twitter data but struggle when filtering out somewhat related, yet undesired, data. The citizen scientists particularly struggle with determining the real-time nature of the sightings, so care must be taken when relying on crowdsourced identification.

The article is open source and free to download from the publisher’s site.

A real-time hybrid aurora alert system: combining citizen science reports with an auroral oval model

The article “A real-time hybrid aurora alert system: combining citizen science reports with an auroral oval model” was recently accepted to the American Geophysical Union (AGU) journal Earth and Space Science. The article, for which Nathan was the lead author, describes how citizen science reports are combined with the Ovation auroral forecast product to produce accurate and localised aurora alerts.

Abstract

Accurately predicting when, and from where, an aurora will be visible is particularly difficult, yet it is a service much desired by the general public. Several aurora alert services exist that attempt to provide such predictions but are, generally, based upon fairly coarse estimates of auroral activity (e.g., Kp or Dst). Additionally, these services are not able to account for a potential observer’s local conditions (such as cloud cover or level of darkness). Aurorasaurus, however, combines data from the well-used, solar wind-driven, OVATION Prime auroral oval model with real-time observational data provided by a global network of citizen scientists. This system is designed to provide more accurate and localized alerts for auroral visibility than currently available. Early results are promising and show that over 100,000 auroral visibility alerts have been issued, including nearly 200 highly localized alerts, to over 2000 users located right across the globe.

The article is open source and free to download from the publisher’s site.

Citizen Scientists Help NASA Researchers Understand Auroras

NASA has posted a feature article about how the Aurorasaurus project and a recent study by Nathan are helping scientists to understand the aurora and estimate where they might be visible from.

“Without the citizen science observations, Aurorasaurus wouldn’t have been able to improve our models of where people can see the aurora,” said the study’s lead author, Nathan Case, a previous Aurorasaurus team member and now a senior research associate at Lancaster University, United Kingdom. “The team is very thankful for our community’s dedication and are excited to have more people sign up.”

The full article can be read here

Using citizen science reports to define the equatorial extent of auroral visibility

The article “Using citizen science reports to define the equatorial extent of auroral visibility” was recently accepted to the American Geophysical Union (AGU) journal Space Weather. The article, for which Nathan was the lead author, describes how citizen science reports from the Aurorasaurus project can be used to determine the extent of auroral visibility and predict how far it might be seen in the future.

Abstract

An aurora may often be viewed hundreds of kilometers equatorward of the auroral oval owing to its altitude. As such, the NOAA Space Weather Prediction Center (SWPC) Aurora Forecast product provides a “view-line” to demonstrate the equatorial extent of auroral visibility, assuming that it is sufficiently bright and high in altitude. The view-line in the SWPC product is based upon the latitude of the brightest aurora, for each hemisphere, as specified by the real-time Oval Variation, Assessment, Tracking, Intensity, and Online Nowcasting (OVATION) Prime (2010) aurora precipitation model. In this study, we utilize nearly 500 citizen science auroral reports to compare with the view-line provided by an updated SWPC aurora forecast product using auroral precipitation data from OVATION Prime (2013). The citizen science observations were recorded during March and April 2015 using the Aurorasaurus platform and cover one large geomagnetic storm and several smaller events. We find that this updated SWPC view-line is conservative in its estimate and that the aurora is often viewable further equatorward than is indicated by the forecast. By using the citizen reports to modify the scaling parameters used to link the OVATION Prime (2013) model to the view-line, we produce a new view-line estimate that more accurately represents the equatorial extent of visible aurora. An OVATION Prime (2013) energy-flux-based equatorial boundary view-line is also developed and is found to provide the best overall agreement with the citizen science reports, with an accuracy of 91%.

You can download the article from Lancaster University’s repository.

Aurorasaurus: a Citizen Science Platform for Viewing and Reporting the Aurora

The article “Aurorasaurus: a Citizen Science Platform for Viewing and Reporting the Aurora” was recently accepted to the American Geophysical Union (AGU) journal Space Weather. The article, which was co-authored by Nathan, describes the Aurorasaurus citizen science project in detail, including its aims and scopes and data collection methods.

Abstract

A new, citizen science based, aurora observing and reporting platform has been developed with the primary aim of collecting auroral observations made by the general public to further improve the modeling of the aurora. In addition, the real-time ability of this platform facilitates the combination of citizen science observations with auroral oval models to improve auroral visibility nowcasting. Aurorasaurus provides easily understandable aurora information, basic gamification, and real-time location-based notification of verified aurora activity to engage citizen scientists. The Aurorasaurus project is one of only a handful of space weather citizen science projects and can provide useful results for the space weather and citizen science communities. Early results are promising with over 2,000 registered users submitting over 1,000 aurora observations and verifying over 1,700 aurora sightings posted on Twitter.

You can download the article from Lancaster University’s repository.

Mapping Auroral Activity with Twitter

The article “Mapping Auroral Activity with Twitter” was recently accepted to the American Geophysical Union (AGU) journal Geophysical Research Letters (GRL). The study presented in the article compared the  daily number of aurora-related tweets to several measures of auroral activity and found that the two data showed strong correlation.

Abstract

Twitter is a popular, publicly-accessible, social media service that has proven useful in mapping large-scale events in real-time. In this study, for the first time, the use of Twitter as a measure of auroral activity is investigated. Peaks in the number of aurora-related tweets are found to frequently coincide with geomagnetic disturbances (detection rate of 91%). Additionally, the number of daily aurora-related tweets is found to strongly correlate with several auroral strength proxies (ravg ≈ 0.7). An examination is made of the bias for location and time of day within Twitter data, and a first order correction of these effects is presented. Overall, the results suggest that Twitter can provide both specific details about an individual aurora and accurate real-time indication of when, and even from where, an aurora is visible.

The work undertaken was a small part of the much bigger Aurorasaurus project.

St Patrick’s Day: a Success for Citizen Science

The article “Aurorasaurus and the St Patrick’s Day storm” was recently accepted for publication in the Royal Astronomical Society (RAS) journal Astronomy & Geophysics (A&G).

The recent St. Patrick’s Day geomagnetic storm provided a rare chance for the public to witness a dazzling auroral display, even from mid-latitudes. An unprecedented number of citizen scientists reported their sightings to Aurorasaurus, offering an exciting opportunity for future scientific study.

The work undertaken was a small part of the much bigger Aurorasaurus project.