EGU21-5986
https://doi.org/10.5194/egusphere-egu21-5986
EGU General Assembly 2021
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Large-scale dune aurora event investigation combining Citizen Scientists' photographs and spacecraft observations

Maxime Grandin1, Minna Palmroth1,2, Graeme Whipps3, Milla Kalliokoski1, Mark Ferrier3, Larry J. Paxton4, Martin G. Mlynczak5, Jukka Hilska6, Knut Holmseth7, Kjetil Vinorum7, and Barry Whenman3
Maxime Grandin et al.
  • 1University of Helsinki, Department of Physics, Helsingin Yliopisto, Finland (maxime.grandin@helsinki.fi)
  • 2Space and Earth Observation Centre, Finnish Meteorological Institute, Helsinki, Finland
  • 3Citizen Scientist, Scotland
  • 4The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
  • 5Atmospheric Sciences Division, NASA Langley Research Center, Hampton, VA, USA
  • 6Citizen Scientist, Finland
  • 7Citizen Scientist, Norway

Recently, citizen scientist photographs led to the discovery of a new auroral form called "the dune aurora" which exhibits parallel stripes of brighter emission in the green diffuse aurora at about 100 km altitude. This discovery raised several questions, such as (i) whether the dunes are associated with particle precipitation, (ii) whether their structure arises from spatial inhomogeneities in the precipitating fluxes or in the underlying neutral atmosphere, and (iii) whether they are the auroral manifestation of an atmospheric wave called a mesospheric bore. This study investigates a large-scale dune aurora event on 20 January 2016 above Northern Europe. The dunes were observed from Finland to Scotland, spanning over 1500 km for at least four hours. Spacecraft observations confirm that the dunes are associated with electron precipitation and reveal the presence of a temperature inversion layer below the mesopause during the event, creating suitable conditions for mesospheric bore formation. The analysis of a time lapse of pictures by a citizen scientist from Scotland leads to the estimate that, during this event, the dunes propagate toward the west-southwest direction at about 200 m/s, presumably indicating strong horizontal winds near the mesopause. These results show that citizen science and dune aurora studies can fill observational gaps and be powerful tools to investigate the least-known region of near-Earth space at altitudes near 100 km.

How to cite: Grandin, M., Palmroth, M., Whipps, G., Kalliokoski, M., Ferrier, M., Paxton, L. J., Mlynczak, M. G., Hilska, J., Holmseth, K., Vinorum, K., and Whenman, B.: Large-scale dune aurora event investigation combining Citizen Scientists' photographs and spacecraft observations, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5986, https://doi.org/10.5194/egusphere-egu21-5986, 2021.

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