EGU2020-2389, updated on 13 Jul 2024
https://doi.org/10.5194/egusphere-egu2020-2389
EGU General Assembly 2020
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Citizen scientists discover a new auroral form: Dunes provide insight into the upper atmosphere

Minna Palmroth1,2, Maxime Grandin1, Matti Helin3, Pirjo Koski3, Arto Oksanen4, Minna Glad3, Rami Valonen3, Kari Saari3, Emma Bruus5, Johannes Norberg2, Ari Viljanen2, Kirsti Kauristie2, and Pekka Verronen2,6
Minna Palmroth et al.
  • 1University of Helsinki, also at: Finnish Meteorological Institute, Helsinki, Finland (minna.palmroth@helsinki.fi)
  • 2Finnish Meteorological Institute, Space and Earth Observation Centre, Helsinki, Finland
  • 3Citizen Scientist, Finland
  • 4Hankasalmi Observatory, Jyväskylän Sirius ry, Finland
  • 5Taivaanvahti service, Finnish Association of Amateur Astronomers (Ursa), Helsinki, Finland
  • 6Sodankyl ̈a Geophysical Observatory, University of Oulu, Finland

Auroral forms are like fingerprints linking optical features to physical phenomena in the near-Earth space. While discovering new forms is rare, recently scientists reported of citizens' observations of STEVE, a pinkish optical manifestation of subauroral ionospheric drifts that were not thought to be visible to the naked eye. Here, we present a new auroral form named "the dunes". On Oct 7, 2018, citizen observers took multiple digital photographs of the same dunes simultaneously from different locations in Finland and Sweden. We develop a triangulation method to analyse the photographs, and conclude that the dunes are a monochromatic wave field with a wavelength of about 45 km within a thin layer at 100 km altitude. Supporting data suggest that the dunes manifest atmospheric waves, possibly mesospheric bores, which are rarely detected, and have not previously been observed via diffuse aurora, nor at auroral latitudes and altitudes. The dunes present a new opportunity to investigate the coupling of the lower/middle atmosphere to the thermosphere and ionosphere. We conclude that the the dunes may provide new insights into the structure of the mesopause as a response to driving by ionospheric energy deposition via Joule heating and electron precipitation. Further, our paper adds to the growing body of work that illustrates the value of citizen scientist images in carrying out quantitative analysis of optical phenomena, especially at small scales at subauroral latitudes. The dune project presents means to create general interest towards physics, emphasising that citizens can take part in scientific work by helping to uncover new phenomena.

How to cite: Palmroth, M., Grandin, M., Helin, M., Koski, P., Oksanen, A., Glad, M., Valonen, R., Saari, K., Bruus, E., Norberg, J., Viljanen, A., Kauristie, K., and Verronen, P.: Citizen scientists discover a new auroral form: Dunes provide insight into the upper atmosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2389, https://doi.org/10.5194/egusphere-egu2020-2389, 2020.

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