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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 110,
A10214,
9 PP., 2005
doi:10.1029/2003JA010242
North-south asymmetry of the amplitude of high-latitude Pc 3–5 pulsations: Observations at conjugate stations
Venture Business Laboratory, Kyushu University, Fukuoka, Japan
Department of Earth and Planetary Sciences, Faculty of Sciences, Kyushu University, Fukuoka, Japan
Geophysical Institute, University of Alaska, Fairbanks, Alaska, USA
Australian Antarctic Division, Department of the Environment and Heritage, Kingston, Tasmania, Australia
Department of Physics, University of Newcastle, Newcastle, New South Wales, Australia
Space Environment Research Center, Kyushu University, Fukuoka, Japan
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.
Received 16 September 2003; accepted 5 May 2005; published 28 October 2005.
Citation: (2005), North-south asymmetry of the amplitude of high-latitude Pc 3–5 pulsations: Observations at conjugate stations, J. Geophys. Res., 110, A10214, doi:10.1029/2003JA010242.
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