Temporal variations of the ion-neutral collision frequency from EISCAT observations in the polar lower ionosphere during periods of geomagnetic disturbances

The ion‐neutral collision frequency in the lower ionosphere (106–135 km) was estimated using data from the European Incoherent Scatter (EISCAT) radar at Tromsø, Norway during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA‐2) campaign in 2009. Vertical component of the ion v...

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Bibliographic Details
Published inJournal of Geophysical Research: Space Physics Vol. 117; no. A5
Main Authors Oyama, S., Kurihara, J., Watkins, B. J., Tsuda, T. T., Takahashi, T.
Format Journal Article
LanguageEnglish
Published Washington, DC Blackwell Publishing Ltd 01.05.2012
American Geophysical Union
Subjects
Atmospheric sciences
Earth sciences
Earth, ocean, space
EISCAT
Exact sciences and technology
ion-neutral collision frequency
Ionosphere
Momentum equation
thermosphere
Norway
Scandinavia
Europe
Norway, Troms, Tromsoe
Energetics
models
Ion neutral collision
time variations
density
velocity
ionosphere
frequency
dynamics
Aurorae
depressions
Radar observation
warming
Incoherent scattering
ions
vertical component
Plasma heating
deltas
radar methods
Geomagnetic disturbance
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Summary:The ion‐neutral collision frequency in the lower ionosphere (106–135 km) was estimated using data from the European Incoherent Scatter (EISCAT) radar at Tromsø, Norway during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA‐2) campaign in 2009. Vertical component of the ion velocity was used with the ion momentum equation for the calculations. The ion‐neutral collision frequency was found to be approximately equivalent to that predicted using modeled density data. However, notable increases were found above 126.8 km during natural ionospheric heating events. A depression in calculated values was also found between 114.6 km and 126.8 km just after cessation of a heating event. This paper discusses contributions of the vertical thermospheric motion to variations of the ion‐neutral collision frequency. Key Points Temporal variations of the ion‐neutral collision frequency were measured Height‐resolved ion‐neutral collision frequency from the IS radar Thermospheric vertical motion in association with auroral heating
Bibliography:istex:585172B423236465A2BDCD40ED4282CA7366A084
ark:/67375/WNG-F549R19T-F
ArticleID:2011JA017159
ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:0148-0227
2169-9380
2156-2202
2169-9402
DOI:10.1029/2011JA017159