Typical spectrum of Schumann resonances (SR) Resonance frequency experiences variations [Balser and Wagner, 1962].
21.1. Effect of the solar activity Sao et al. [1973] compared the first mode frequency at Tottory observatory (35º latitude) and solar X-ray intensity during the December 1971 – February 1972 period. A good similarity between day-to-day variations of both parameters was found. Schlegel and Füllekrug...
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.494.2255 http://www.oa.uj.edu.pl/konferencje/2004dwerniczek/prezentacje/Jurij.Maltsev/maltsev_bieszczady.pdf |
| Summary: | 21.1. Effect of the solar activity Sao et al. [1973] compared the first mode frequency at Tottory observatory (35º latitude) and solar X-ray intensity during the December 1971 – February 1972 period. A good similarity between day-to-day variations of both parameters was found. Schlegel and Füllekrug [1999] examined changes of the daily averaged first SR frequency at Arrival Heights, Antarctica, for nine strong SPEs and found that the frequency increased by about 0.04-0.14 Hz for the SPE days. The authors related this increase with proton precipitation and not with X-ray bursts. Kulak et al. [2003a,b] examined the changes of the characteristic frequencies of the first resonance during the minimum and maximum of the solar cycle, based of the measurements held in the Carpatian mountains, and found that the frequency grew up clearly during the active phase of solar cycle. It is possible that the increase is caused by the enhanced X-ray activity. Roldugin et al. [1999, 2001, 2003, 2004a] studied effects of X-rays and SPE separately. Roldugin et al. [2004a] studied variations of the Schumann resonance frequency in the Kola and Kamchatka Peninsulas during seven days of March – April, 2001, when the intensive solar X-ray bursts occurred. All X-ray bursts were accompanied by ~0.2 Hz increase in the first mode frequency, at least in one of the magnetic components. For the second mode the increase (in average by ~0.3 Hz) was registered in most events, when the ELF noise level was not very high. 3Solid lines: the 1st Schumann resonance frequency at the Kola peninsula. Dotted lines: the solar X-ray intensity onboard GOES 10 satellite. Dashed lines: the frequency diurnal variations for undisturbed days. 4The 1st Schumann resonance frequency in Kamchatka peninsula in H, D and Z components. The vertical lines mark the peaks of the solar X-ray bursts. 5Roldugin et al. [1999, 2001, 2003] studied variations in the first mode SR frequency during SPEs. |
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