ELF Electromagnetic Waves and Ionospheric Physics Seminar
June 24, 2026
Jose Tacza (Institute of Geophysics PAS, Warsaw, Poland)
"Intermittent 8-29-Day Schumann Resonance Frequency Variability and Its High-Latitude Response to Recurrent Solar-Wind Streams"
Abstract:
Schumann resonance (SR) frequencies are sensitive to changes in the effective Earth-ionosphere
cavity and may therefore respond to solar-wind and geomagnetic forcing. We investigate
whether high-latitude first-mode frequency (F1) SR variability reflects a persistent solar-rotation
signal or intermittent modulation during selected geophysical conditions. Daily SR F1
measurements from Hornsund, Ivalo, and Rovaniemi during 2004/2005-2024 were analyzed
using wavelet-based analysis in the 25-29-, 12-15-, and 8-11-day bands, together with cross-
wavelet and wavelet-coherence comparisons against solar-wind, geomagnetic, solar, and
lightning proxies. The full record does not support a persistent 25-29-day SR oscillation. Instead,
SR variability is intermittent, with 8 intervals detected in the 25-29-day band, 29 in the 12-15-
day band, and 68 in the 8-11-day band; only 2, 4, and 25 of these intervals, respectively, show
multistation support. The clearest retained associations occur with solar-wind speed and
geomagnetic indices, including a late-2020 25-29-day case observed at all three stations. To test
recurrent solar-wind forcing directly, we analyzed 173 threshold-defined high-speed
stream/corotating interaction region proxy onsets using superposed epoch composites. HSS/CIR
onsets are followed by a small but repeatable F1 increase on days 0 to +1, strongest at polar
Hornsund and also detectable at Ivalo and Rovaniemi. Event-level scaling is most clearly
organized by Kp impulses, with additional support from AE and a weaker relation with solar-
wind speed.
Contact: Contact_ELFseminar(at)oa.uj.edu.pl
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