Enhanced incoherent scatter plasma lines

Enhanced incoherent scatter plasma lines

Detailed model calculations of auroral secondary and photoelectron distributions for varying conditions have been used to calculate the theoretical enhancement of incoherent scatter plasma lines. These calculations are compared with EISCAT UHF radar measurements of enhanced plasma lines from both the E and F regions, and published EISCAT VHF radar measurements. The agreement between the calcula...

Analysis of beam plasma instability effects on incoherent scatter spectra

Naturally Enhanced Ion Acoustic Lines (NEIALs) detected with Incoherent Scatter Radars (ISRs) can be produced by a Langmuir decay mechanism, triggered by a bump on tail instability. A recent model of the beam-plasma instability suggests that weak-warm beams, such those associated with NEIAL events, might produce Langmuir harmonics which could be detected by a properly configured ISR. The analys...

Substorm Triggering by New Plasma Intrusion: Incoherent-Scatter Radar Observations

In the companion paper, we identified a repeatable sequence of events leading to substorm onset in THEMIS all-sky imager observations: enhanced flows bring new plasma into the plasma sheet. The new plasma then moves earthward as a flow channel, bringing it to the near-Earth plasma sheet and where it produces onset instability. New plasma entering the dusk (dawn) convection cell drifts equatorwa...

Auroral field-aligned currents by incoherent scatter plasma line observations in the E region

The aim of the Swedish-Japanese EISCAT campaign in February 1999 was to measure the ionospheric parameters inside and outside the auroral arcs. The ion line radar experiment was optimised to probe the E-region and lower F-region with as high a speed as possible. Two extra channels were used for the plasma line measurements covering the same altitudes, giving a total of 3 upshifted and 3 downshi...

Incoherent Scatter Radar Observations of Westward Electric Fields and Plasma Densities in the Auroral Ionosphere, 1