Simultaneous observations of small multi-scale structures in an auroral arc

• Published in: Journal of atmospheric and solar-terrestrial physics Vol. 72; no. 7; pp. 633 - 637
• Main Authors: Dahlgren, H., Aikio, A., Kaila, K., Ivchenko, N., Lanchester, B.S., Whiter, D.K., Marklund, G.T.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2010; Elsevier
• Subjects: Auroral curls and folds; Auroral fine structure; Earth, ocean, space; Exact sciences and technology; External geophysics; Fysik; Geocosmophysics and plasma physics; Geokosmofysik och plasmafysik; Instruments and techniques; NATURAL SCIENCES; NATURVETENSKAP; Physics; Physics of the ionosphere; Physics of the magnetosphere; Plasma instabilities; Plasma physics; Plasmafysik; Rymdfysik; Space physics; Auroral fine structure; Plasma instabilities; Auroral curls and folds; Instruments and techniques; Fine structure; Auroral arc; shear; Plasma instability; Vortex street; Small scale structure; deformation; Simultaneous observation
• ISSN: 1364-6826; 1879-1824; 1879-1824
• DOI: 10.1016/j.jastp.2010.01.014

Auroral arcs can develop small-scale distortions known as vortex streets or curls. Other common and somewhat larger spatially periodic distortions are auroral folds. In this event study we present simultaneous wide and narrow field imager observations of a third kind of structuring, on even smaller spatial scales. Boundary undulations, or “ruffs”, have been observed to form on the edge of an auroral arc and they occur superimposed on curls, folds or at times of auroral shear. The undulations typically have wavelengths of less than 3 km and amplitudes of less than 800 m. They are observed to move on the edge of the arc, with velocities of about 11 km/s. These observations, with multi-scale deformations, reveal a much more intricate structuring of auroral arcs than previously found.