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Magnetic Activity and Schumann Resonance

12/01/2003 - Problem with Schumann resonance calculation resolved

Characteristics of integrated spectra and parameters of the first Earth-ionosphere cavity resonance are being computed by programs supplied by Dr. Martin Fullekrug based on data recorded by the electromagnetic observatories recorded by the BSL. This collaboration was initiated when Dr. Fullekrug was at the Stanford STAR Laboratory.

The results of the numerical analysis characterize the considered frequency range and its variations, spaced by 15 minute intervals. Thirteen average spectral estimates are calculated in pt**2/Hz and describe the magnetic activity (MA-Index) in different frequency bands.

Magnetic Activity Analysis

Index

Period

Frequency (Hz)

MA1
600 - 1800
0.00056 - 0.0017
MA2
300 - 600
0.0017 - 0.0033
MA3
150 - 300
0.0033 - 0.0067
MA4
100 - 150
0.0067 - 0.0100
MA5
45 - 100
0.010 - 0.022
MA6
20 - 45
0.022 - 0.050
MA7
10 - 20
0.05 - 0.10
MA8
5 - 10
0.10 - 0.20
MA9
2 - 5
0.20 - 0.50
MA10
1 - 2
0.50 - 1.00
MA11
0.5 - 1
1.00 - 2.00
MA12
0.17 - 0.5
2.00 - 6.00
MA13
0.1 - 0.17
6.00 - 10.00

The MA index from 6-10 Hz covers the first Earth-ionosphere cavity, or Schumann Resonance on the background spectrum in the shape of a Lorentzian resonance curve, characterized by its amplitude (pT), damping (Hz) and center frequency (Hz). These parameters are derived with the Prony algorithm.

The results of daily magnetic activity and Schumann resonance are available via anonymous ftp at the NCEDC. The README file provides some additional information.

Stability of the Schumann Resonance

The Schumann resonance frequency observed at this observatory does not exhibit any unusual change or drift since the start of observations by the BDSN in 1995.

Figures 1 and 2 below, which show the daily averages of the first Earth-ionosphere cavity resonance frequency measured at the PKD station in Parkfield and at the Arrival Heights station in Artarctica, exhibit a typical natural variability < 0.3 Hz. This variability results from the solar short wave radiation, which ionises the atmosphere at 90-100 km height. (Figures by Dr. Martin Fullekrug.)



Figure 1: Variability of the first Earth-ionosphere cavity resonance at Parkfield, California.

Figure 2: Variability of the first Earth-ionosphere cavity resonance at Arrival Heights, Antarctica.

For more details of analysis please see Dr. Martin Fullekrug.