Incoherent scatter radar estimation ofFregion ionospheric composition during frictional heating events

Abstract

[1] A method is developed for estimating F region ion composition from incoherent scatter radar (ISR) measurements during times of frictional ion heating. The technique addresses ion temperature-mass ambiguities in the IS spectra by self-consistently modeling ion temperature profiles, including the effects of ion temperature anisotropies and altitude-independent neutral winds. The modeled temperature profiles are used in a minimization procedure to estimate ion composition consistent with the recorded IS spectra. The proposed method is applicable to short-integration (<5 min) data sets from either single-beam or multiple-beam experiments. Application of the technique to Sondrestrom ISR measurements shows increases in F region molecular ions in response to frictional heating, a result consistent with previous theoretical and observational work. Estimates of ion composition are shown to be relatively insensitive to moderate variations in the neutral atmospheric model, which serves as input to the method. The technique developed in this work is uniquely qualified for studying highly variable ion composition near auroral arcs and associated processes such as molecular ion upflows. It also addresses a systematic source of error in standard ISR analysis methods when they are applied in such situations.

VISIONS remote observations of a spatially-structured filamentary source of energetic neutral atoms near the polar cap boundary during an auroral substorm

“…4 is that the accelerated ions are coincident with a region where DC electric fields are high enough ($90 mV/m, see panel (c)) to elicit a fairly strong ionospheric response in terms of type-1 upflows (e.g., Wahlund et al (1992)) and substantial increases in molecular ion concentrations (e.g., Zettergren et al (2011Zettergren et al ( , 2014). Both the upflows and molecular ion enhancements are initiated by strong frictional heating due to the ExB drifts of the ionosphere through the background neutral atmosphere.…”

New opportunities offered by Cubesats for space research in Latin America: The SUCHAI project case

“…The majority of the backscattered power from the ionosphere is confined within a narrow (typically tens of kHz at UHF center frequencies) double humped band centered close by to the transmitted frequency. This is referred to as the ion line, or ion spectrum, and its shape is described by ionospheric parameters such as electron to ion temperature ratios, ion drift velocities, and electron density, ion composition, among others (Zettergren et al, 2011). A second mode, more difficult to detect but still accessible to ISRs, is the Langmuir mode, which is manifest in narrow bands offset from the carrier by the mean plasma frequency of the backscatter volume.…”

Model‐Based Inversion of Auroral Processes

“…Regions adjacent to the optical aurora are known to experience enhanced convective flow and attendant increases in T i [Marklund, 1984]. Zettergren et al [2011] has developed an inverse problem that uses measurements of enhanced T i in these regions (e.g., Figure 6) to estimate ion composition effects. Semeter et al…”