Dependence of ground-based Pc5 ULF wave power on F10.7 solar radio flux and solar cycle phase |
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| Authors: | Kyle R Murphy Ian R Mann I Jonathan Rae David K Milling |
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| Institution: | 1. Solar-Terrestrial Environment Laboratory, Nagoya University, Nagoya, Japan;2. Centre for Science, Athabasca University, 1 University Drive, Athabasca, Alberta, Canada T9S 3A3;1. Department of Physics, University of Ilorin, Ilorin, Nigeria;2. Department of Physics, Landmark University, Omu Aran, Kwara State, Nigeria;1. Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow 119991, Russia;2. Space Research Institute RAS, Moscow, Russia;3. Physics Department, Science Faculty, Universidad de Santiago de Chile (USACH), Chile;1. INAF-Istituto di Astrofisica e Planetologia Spaziali, Via del Fosso del Cavaliere 100, 00133, Roma, Italy;2. Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Roma, Italy;1. Department of Physics, West Virginia University, Morgantown, WV 26506, USA;2. NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA;3. Southwest Research Institute, San Antonio, TX 78228, USA;4. University of Texas at San Antonio, San Antonio, TX 78249, USA;1. West Department of Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation RAS, Pobedy Av., 41, Kaliningrad 236017, Russia;2. Institute of Solar-Terrestrial Physics, 126a Lermontov St., P.O. Box 291, Irkutsk 664033, Russia |
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| Abstract: | Utilising fifteen (1990–2005) years of ground-based magnetometer data from four magnetometer stations, we characterise the statistical dependence of the Pc5 ULF wave power spectra on variations in F10.7 solar radio flux and on solar cycle phase. We show that the median Pc5 ULF wave power spectra can be characterised as a power-law with a localised Gaussian centred at a specific frequency superimposed on the power-law spectrum. Further, we demonstrate that the location of the Gaussian in frequency systematically varies with both solar cycle phase and F10.7 and is more pronounced during high-speed solar wind intervals. We postulate that the localised power spectrum enhancement (or Gaussian) is a manifestation of the local eigenfrequency of field line resonances in the Earth's magnetosphere and that the variation in the location of the Gaussian occurs as a result of increased ionospheric outflow during periods of enhanced F10.7 and active solar activity. |
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