Electrodynamics of an omega-band as deduced from optical and magnetometer data

Heikki Antero Vanhamaki, K. Kauristie, O. Amm, A. Senior, D. Lummerzheim, S. Milan

Research output: Contribution to journalArticle

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Abstract

We investigate an omega-band event that took place above northern Scandinavia around 02:00-02:30 UT on 9 March 1999. In our analysis we use ground based magnetometer, optical and riometer measurements together with satellite based optical images. The optical and riometer data are used to estimate the ionospheric Hall and Pedersen conductances, while ionospheric equivalent currents are obtained from the magnetometer measurements. These data sets are used as input in a local KRM calculation, which gives the ionospheric potential electric field as output, thus giving us a complete picture of the ionospheric electrodynamic state during the omega-band event. The overall structure of the electric field and field-aligned current (FAC) provided by the local KRM method are in good agreement with previous studies. Also the E ×B drift velocity calculated from the local KRM solution is in good qualitative agreement with the plasma velocity measured by the Finnish CUTLASS radar, giving further support for the new local KRM method. The high-resolution conductance estimates allow us to discern the detailed structure of the omega-band current system. The highest Hall and Pedersen conductances, ∼50 and ∼25 S, respectively, are found at the edges of the bright auroral tongue. Inside the tongue, conductances are somewhat smaller, but still significantly higher than typical background values. The electric field shows a converging pattern around the tongues, and the field strength drops from ∼40 mV/m found at optically dark regions to ∼10 mV/m inside the areas of enhanced conductivity. Downward FAC flow in the dark regions, while upward currents flow inside the auroral tongue. Additionally, sharp conductance gradients at the edge of an auroral tongue are associated with narrow strips of intense FACs, so that a strip of downward current flows at the eastern (leading) edge and a similar strip of upward current is present at the western (trailing) edge. The Joule heating follows the electric field pattern, so that it is diminished inside the bright auroral tongue.

Original languageEnglish
Pages (from-to)3367-3385
Number of pages19
JournalAnnales Geophysicae
Volume27
Issue number9
DOIs
Publication statusPublished - Dec 1 2009

Fingerprint

tongue
electrodynamics
magnetometer
magnetometers
electric field
ionospherics
riometers
strip
field aligned currents
electric fields
Scandinavia
conductivity
trailing edges
Joule heating
radar
estimates
leading edges
heating
optical measurement
plasma

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Geology
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Vanhamaki, H. A., Kauristie, K., Amm, O., Senior, A., Lummerzheim, D., & Milan, S. (2009). Electrodynamics of an omega-band as deduced from optical and magnetometer data. Annales Geophysicae, 27(9), 3367-3385. https://doi.org/10.5194/angeo-27-3367-2009

Electrodynamics of an omega-band as deduced from optical and magnetometer data. / Vanhamaki, Heikki Antero; Kauristie, K.; Amm, O.; Senior, A.; Lummerzheim, D.; Milan, S.

In: Annales Geophysicae, Vol. 27, No. 9, 01.12.2009, p. 3367-3385.

Research output: Contribution to journalArticle

Vanhamaki, HA, Kauristie, K, Amm, O, Senior, A, Lummerzheim, D & Milan, S 2009, 'Electrodynamics of an omega-band as deduced from optical and magnetometer data', Annales Geophysicae, vol. 27, no. 9, pp. 3367-3385. https://doi.org/10.5194/angeo-27-3367-2009
Vanhamaki HA, Kauristie K, Amm O, Senior A, Lummerzheim D, Milan S. Electrodynamics of an omega-band as deduced from optical and magnetometer data. Annales Geophysicae. 2009 Dec 1;27(9):3367-3385. https://doi.org/10.5194/angeo-27-3367-2009
Vanhamaki, Heikki Antero ; Kauristie, K. ; Amm, O. ; Senior, A. ; Lummerzheim, D. ; Milan, S. / Electrodynamics of an omega-band as deduced from optical and magnetometer data. In: Annales Geophysicae. 2009 ; Vol. 27, No. 9. pp. 3367-3385.
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