Incoherent scatter ion line enhancements and auroral arc-induced Kelvin-Helmholtz turbulence
2015 (English)In: Journal of Atmospheric and Solar-Terrestrial Physics, ISSN 1364-6826, E-ISSN 1879-1824, Vol. 122, 119-128 p.Article in journal (Refereed) Published
We present two cases of incoherent-scatter ion line enhancements in conjunction with auroral arcs drifting through the radar beam. The up- and downshifted ion line shoulders as well as the spectral region between them are enhanced equally and simultaneously. The power enhancements are one order of magnitude above the thermal level and are concentrated in less than 15 km wide altitude ranges at the ionospheric F region peak. The auroral arc passages are preceded by significantly enhanced ion temperatures in the E region, which are shown to generate high velocity shears. We use a Hall MHD model of velocity shears perpendicular to the geomagnetic field and show that a Kelvin-Helmholtz instability will grow for the two presented cases. We assess the possibility that the subsequently generated low frequency turbulence can explain the observed spectrally uniform ion line power enhancements.
Place, publisher, year, edition, pages
Oxford: Pergamon Press, 2015. Vol. 122, 119-128 p.
auroral ionosphere, radar observations, plasma waves and instabilities
Geochemistry Geophysics Meteorology and Atmospheric Sciences
IdentifiersURN: urn:nbn:se:umu:diva-42828DOI: 10.1016/j.jastp.2014.10.018ISI: 000348627300013OAI: oai:DiVA.org:umu-42828DiVA: diva2:410483