EISCAT Svalbard radar observations of SPEAR-induced E- and F-region spectral enhancements in the polar cap ionosphere
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 EI...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2007-08-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/25/1801/2007/angeo-25-1801-2007.pdf |
| Summary: | 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. |
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| ISSN: | 0992-7689 1432-0576 |