the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 16 Jul 2026
Global Citizen-Science Observations of Fragmented Aurora-Like Emissions
Abstract. Fragmented aurora-like emissions (fragments) are small-scale green E-region structures that have previously been reported mainly from high-latitude locations near the poleward auroral oval boundary. Here we present a global citizen-science dataset of 26 fragment observations from 2017 to 2025, collected through an international citizen-science campaign via the Skywarden platform. The observations span magnetic latitudes from approximately 53 to 76°, a wide range of magnetic local times and activity levels, both hemispheres, and diverse auroral conditions. The dataset substantially extends the observational record of fragments beyond previously reported high-latitude regions. Both isolated fragments (type I) and the quasi-periodic wave-like fragments (type II) are represented in this broader geographical context.
To assess fragment locations relative to the auroral oval, three case studies combining satellite observations with ground-based auroral images were analysed in detail. These demonstrate that fragments occur poleward of the oval in Antarctica, equatorward of the oval in Manitoba, and within the oval near the diffuse-discrete boundary in Iceland. Together, the global dataset and case studies show that fragments occur across a much broader range of auroral and geomagnetic conditions and oval positions than previously documented. The results demonstrate the scientific value of citizen-science observations for studying short-lived and localised auroral phenomena.
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Status: open (until 24 Sep 2026)
- RC1: 'Comment on egusphere-2026-3756', Anonymous Referee #1, 24 Aug 2026 reply
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RC2: 'Comment on egusphere-2026-3756', Anonymous Referee #2, 16 Sep 2026
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This paper shows Global Citizen-Science Observations of Fragmented Aurora-Like Emissions, the exisence and the confirmation of FAEs in different aurora reigon is one step forward to fully understand FAEs.
1. However, to identify FAEs from some photos cited in this paper is very hard. The specifications of the camera vary widely, which can make the aurora photo quite differnt. Some aurora ray can also be very bright at low altitude , which could show like Fig1b and fig1e, or even like Figure 6. A clear event, like Figure 3, is suitable for this study.
2. It is hard to find all the events of Appendix A from https://www.taivaanvahti.fi/, it suggested to upload all the event photos as the Supplementary.Citation: https://doi.org/10.5194/egusphere-2026-3756-RC2
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- 1
This study expanded the investigation of auroral fragment occurrence distributions to an unprecedentedly wide range of latitudes and magnetic local times, using the archive Skywarden, which contains aurora images taken by citizen scientists. Aurora researchers verified the images to ensure the academic value of the dataset, and comparisons were made with other measurement data. Each survey topic was carefully examined, and the results are reliable. However, there are aspects of the manuscript structure that require improvement. I have proposed some comments for clearly describing the scientific objectives and focusing the explanation on their elucidation. I hope that the authors will revise the manuscript in line with the comments below.
[Major Comment 1]
The scientific objectives of this study are stated at the end of Section 1: “The aim was to investigate where fragments can form, under which solar-wind and geomagnetic conditions they are observed, and how their locations relate to the auroral oval.” Three scientific objectives were proposed and investigated in 26 fragment events. The distinction between the first and third scientific objectives is not clear, but probably the third is the essential one. To address this, the study examined the relative locations of ground-based observation locations with respect to the auroral oval observed by DMSP/SSUSI. As described in the second paragraph of Section 2.4, a comparison with the auroral oval was made for all events, but results are shown for only three cases (Sections 3.2.1-3). Figure 2b provides the magnetic latitude distribution of the observation locations, but their relative positions with respect to the auroral oval are not provided. The observation that fragments occur both inside and outside the oval can be considered a new finding, but presenting the relative distribution of the oval for all 26 cases would make it an even more scientifically valuable new finding. Relative location is discussed in Section 4.2, but except for the three cases compared with DMSP/SSUSI data, almost no results are introduced. This section should be revised to discuss all events.
[Major Comment 2]
This is another comment regarding the scientific objectives. For the second objective, solar wind parameters and geomagnetic indices near the time of event occurrence were examined. However, only three cases (Sections 3.2.1-3) are shown. Of course, it is not realistic to display graphs for all 26 cases, but these three are not presented as representative cases in answering the second objective. It was difficult to obtain an answer to this objective from these three cases, so the answer to this objective is not explicitly stated in Section 5 (Conclusions). If further analysis is necessary, one option would be to remove this topic from the research objectives. However, in that case, it would be necessary to significantly revise the figures and content.
[Minor Comments]
Line 30: “Dayton-Oxland et al., 2025”
Line 109–111: “Events located between … as poleward.”
These results are not provided in the text and figures. Please add the breakdown of the 26 events to Table A1. Also, for "subauroral" and "poleward" cases, calculate and provide the relative magnetic latitude in degrees to the poleward/equatorward edge of the auroral oval. For "auroral" cases, set the relative magnetic latitude to 0°. By comparing these results with the magnetic latitudes of fragments reported in previous studies, explain the progress since their results.
Lines 126–127: “… with links provided in the event list in Appendix A.”
The link in the event list appears to be just plain text, which means there is no direct link to the website.
Lines 141–143: “Figure 2c shows … colour-coded to IMF Bz.”
Events #10, 11, and 12 might have been missed.
Please change the color map so that Bz = 0 is recognizable.
Lines 142–143: “The mean values … each fragment event.”
For solar wind parameters, it is understandable to use the mean value over 1 hour before the event as a representative value, considering the travel time from the satellite measurement point to the front side of the magnetosphere and magnetospheric/ionospheric response delays. On the other hand, what is the reason for also using the mean AL index in the hour before the event as an indicator of ionospheric current conditions? Furthermore, what is the reason for not using IMAGE magnetometer index instead of AL and AU?
Figures 3 and 6: I do not understand the academic rationale for adding constellations and star names. Please state in the text the reason why their inclusion is considered to aid understanding of the research topic. If there is no specific reason, please remove them from the figures. Note that direction can be sufficiently understood from the symbols (e.g., S) annotated in the photos.