R. S. Dhillon

EISCAT Svalbard radar observations of SPEAR-induced E- and F-region spectral enhancements in the polar cap ionosphere

Abstract. The Space Plasma Exploration by Active Radar (SPEAR) facility has successfully operated in the high-power heater and low-power radar modes and has returned its first results. The high-power results include observations of SPEAR-induced ion and plasma line spectral enhancements recorded by the EISCAT Svalbard UHF incoherent scatter radar system (ESR), which is collocated with SPEAR. These SPEAR-enhanced spectra possess features that are consistent with excitation of both the purely growing mode and the parametric decay instability. In this paper, we present observations of upper and lower E-region SPEAR-induced ion and plasma line enhancements, together with F-region spectral enhancements, which indicate excitation of both instabilities and which are consistent with previous theoretical treatments of instability excitation in sporadic E-layers. In agreement with previous observations, spectra from the lower E-region have the single-peaked form characteristic of collisional plasma. Our observations of the SPEAR-enhanced E-region spectra suggest the presence of variable drifting regions of patchy overdense plasma, which is a finding also consistent with previous results.

First results of a ULF wave injected on open field lines by Space Plasma Exploration by Active Radar (SPEAR)

[1] We present strong evidence that on 23 February 2007 between 2230 and 2330 UT the Space Plasma Exploration by Active Radar (SPEAR) system successfully modified the ionospheric electron density inside the northern polar cap. The modulated modification led to the generation of a small-scale ultralow frequency (ULF) wave on open field lines which was detected by ground-based magnetometers in the vicinity of the radar. It was not registered by magnetometer stations elsewhere inside the northern polar cap or at lower latitudes. The solar wind conditions are investigated, and although wave activity at the modulation frequency is present, it is shown that the local ULF wave is unlikely to originate from that activity.

A statistical study of the spatial distribution of Co-operative UK Twin Located Auroral Sounding System (CUTLASS) backscatter power during EISCAT heater beam-sweeping experiments

This paper was published as Journal of Geophysical Research: Space Physics, 2010, 115, A05307. It is also available from http://www.agu.org/pubs/crossref/2010/2009JA014659.shtml. Doi: 10.1029/2009JA014659