Electrodynamic structure of the morning high-latitude trough region

H. Vanhamäki, A. Aikio, M. Voiculescu, L. Juusola, T. Nygrén, R. Kuula

Research output: Contribution to journalArticle

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Abstract

We describe the electrodynamics of a postmidnight, high-latitude ionospheric trough, observed with the European Incoherent Scatter radar in northern Scandinavia on 24-25 June 2003 around 22:00-02:30 UT during quiet conditions. The UHF radar made meridian scans with a 30 min cadence resulting in nine cross sections of ionospheric parameters. The F region electric field was also determined with the tristatic system. Ionospheric equivalent currents, calculated from ground magnetometer data, mostly show an electrojet-like current that is reasonably uniform in the longitudinal direction. Combined analysis of the conductances and equivalent current with a local Kamide-Richmond-Matsushita (KRM) method yields the ionospheric electric field and field-aligned current (FAC) in a 2-D (latitude-longitude) area around the radar. We conclude that the most likely scenario is one where the trough is initially created poleward of the auroral oval by downward FAC that evacuates the F region, but as the trough moves to lower latitudes during the early morning hours, it becomes colocated with the westward electrojet. There the electron density further decreases due to increased recombination caused by enhanced ion temperature, which in turn is brought about by a larger convection speed. Later in the morning the convection speed decreases and the trough is filled by increasing photoionization.

Original languageEnglish
Pages (from-to)2669-2682
Number of pages14
JournalJournal of Geophysical Research A: Space Physics
Volume121
Issue number3
DOIs
Publication statusPublished - Mar 1 2016

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morning
electrodynamics
radar
Electrodynamics
troughs
F region
polar regions
ionospherics
trough
Radar
electric field
electrojets
field aligned currents
electrojet
Electric fields
Photoionization
convection
EISCAT radar system (Europe)
longitude
Scandinavia

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Cite this

Vanhamäki, H., Aikio, A., Voiculescu, M., Juusola, L., Nygrén, T., & Kuula, R. (2016). Electrodynamic structure of the morning high-latitude trough region. Journal of Geophysical Research A: Space Physics, 121(3), 2669-2682. https://doi.org/10.1002/2015JA022021

Electrodynamic structure of the morning high-latitude trough region. / Vanhamäki, H.; Aikio, A.; Voiculescu, M.; Juusola, L.; Nygrén, T.; Kuula, R.

In: Journal of Geophysical Research A: Space Physics, Vol. 121, No. 3, 01.03.2016, p. 2669-2682.

Research output: Contribution to journalArticle

Vanhamäki, H, Aikio, A, Voiculescu, M, Juusola, L, Nygrén, T & Kuula, R 2016, 'Electrodynamic structure of the morning high-latitude trough region', Journal of Geophysical Research A: Space Physics, vol. 121, no. 3, pp. 2669-2682. https://doi.org/10.1002/2015JA022021
Vanhamäki H, Aikio A, Voiculescu M, Juusola L, Nygrén T, Kuula R. Electrodynamic structure of the morning high-latitude trough region. Journal of Geophysical Research A: Space Physics. 2016 Mar 1;121(3):2669-2682. https://doi.org/10.1002/2015JA022021
Vanhamäki, H. ; Aikio, A. ; Voiculescu, M. ; Juusola, L. ; Nygrén, T. ; Kuula, R. / Electrodynamic structure of the morning high-latitude trough region. In: Journal of Geophysical Research A: Space Physics. 2016 ; Vol. 121, No. 3. pp. 2669-2682.
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