North-south asymmetry of the amplitude of high-latitude Pc 3-5 pulsations: Observations at conjugate stations

Yuki Obana, Akimasa Yoshikawa, John V. Olson, Ray J. Morris, Brian J. Fraser, Kiyohumi Yumoto

Research output: Contribution to journalArticle

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Abstract

The north-south asymmetry of the amplitude of ULF pulsations in the Pc 3-5 band is studied using magnetic field data from the magnetically conjugate stations at L ∼ 5.4: Kotzebue (KOT) in the northern hemisphere and Macquarie Island (MCQ) in the southern hemisphere. We obtained the following results for the northward (H) component of magnetic pulsations: (1) The north to south power ratio shows a maximum in the northern winter and a minimum in the northern summer. This "seasonal variation" is stronger at higher frequencies (Pc 3 and Pc 4 frequencies). (2) The north to south power ratio for the Pc 4 and Pc 5 frequency band is basically greater than 1.0 for all seasons. This "positive offset" is stronger at lower frequencies. The "seasonal variation" implies that the magnetohydrodynamic (MHD) waves incident from the magnetosphere are more strongly shielded when the ionospheric conductivity is higher. The "positive offset" may result from the difference of the background magnetic field intensity between KOT and MCQ.

Original languageEnglish
Article numberA10214
JournalJournal of Geophysical Research: Space Physics
Volume110
Issue numberA10
DOIs
Publication statusPublished - Jan 1 2005

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annual variations
polar regions
asymmetry
seasonal variation
stations
ionospheric conductivity
Magnetic fields
magnetic field
Magnetosphere
Southern Hemisphere
Northern Hemisphere
magnetic fields
magnetohydrodynamic waves
Magnetohydrodynamics
magnetohydrodynamics
magnetospheres
winter
Frequency bands
magnetosphere
summer

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

North-south asymmetry of the amplitude of high-latitude Pc 3-5 pulsations : Observations at conjugate stations. / Obana, Yuki; Yoshikawa, Akimasa; Olson, John V.; Morris, Ray J.; Fraser, Brian J.; Yumoto, Kiyohumi.

In: Journal of Geophysical Research: Space Physics, Vol. 110, No. A10, A10214, 01.01.2005.

Research output: Contribution to journalArticle

Obana, Yuki ; Yoshikawa, Akimasa ; Olson, John V. ; Morris, Ray J. ; Fraser, Brian J. ; Yumoto, Kiyohumi. / North-south asymmetry of the amplitude of high-latitude Pc 3-5 pulsations : Observations at conjugate stations. In: Journal of Geophysical Research: Space Physics. 2005 ; Vol. 110, No. A10.
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