Image of dune aurora taken by a citizen scientist
Image of the dune aurora taken by a citizen scientist during the 20 January 2016 event from Aura, Finland. Credit: Grandin et al. [2021], Figure 1a
Source: AGU Advances

Grandin et al. [2021] present new observations of an auroral phenomenon referred to as dunes which has been photographed by citizen scientists over northern Europe. The features appear as aurorae in terms of their light emission characteristics, but their structure is more banded. The authors suggest that the underlying mechanism for this banded structure is modulation of the atmospheric density by a horizontally propagating atmospheric bore, following a wave guide formed by a temperature inversion detected in the upper mesosphere. Auroral particle excitation of the bore’s trailing wave pattern results in the appearance of the dunes. Using a combination of surface and satellite observations, the authors derive wavelength and propagation speed for the dune feature, relating the latter to characteristics of the upper mesosphere. Strong horizontal neutral winds and electron precipitation play a role.

Citation: Grandin, M., Palmroth, M., Whipps, G. et al. [2021]. Large-scale dune aurora event investigation combining Citizen Scientists’ photographs and spacecraft observations. AGU Advances, 2, e2020AV000338.  

—Mary Hudson, Editor, AGU Advances

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