ANGEOD Annales Geophysicae Discussions ANGEOD Ann. Geophys. Discuss. 2568-6402 Göttingen, Germany 10.5194/angeo-2021-66 Are drivers of northern lights in the ionosphere? Saka Osuke https://orcid.org/0000-0002-8382-7825 1 Office Geophysik, Ogoori, 838-0141, Japan 12 11 2021 2021 1 9 Copyright: © 2021 Osuke Saka 2021 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://angeo.copernicus.org/preprints/angeo-2021-66/ The full text article is available as a PDF file from https://angeo.copernicus.org/preprints/angeo-2021-66/angeo-2021-66.pdf

<p>Known as northern lights, auroral spirals are distinct features of substorm auroras composed of large-scale spirals (100s&thinsp;km Surges) mixed with smaller scale ones (10s&thinsp;km Folds, and 1&thinsp;km Rays). Spiral patterns are generally interpreted in terms of the field line mapping of the upward field-aligned currents produced in the magnetosphere during the field line dipolarization. The field line mapping results in opposing spiral rotations of small- and large-scale auroras. Because of a rotational symmetry deformation and similarity in deformation speeds (6~8&thinsp;km/s) of small- and large-scale spirals, it has been suggested that common physical processes may underlie the deforming processes. Internal processes in the polar ionosphere (ionospheric driver) will be proposed as the general dynamic for spiral auroras. The ionospheric driver rotated in the ionosphere to produce spirals that characteristically differ from the field line mapping scenario.</p>