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Abstract:
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Three 60 d sections of geomagnetic data from Honolulu Observatory during 2001-2 were analyzed using multitaper spectral analysis, showing the ubiquitous presence of narrowband, very statistically significant, high Q features in multitaper power spectra and pervasive non-stationarity as measured by the frequency offset coherence over 400-4000 µHz. The peak frequencies correlate well with the optically-measured frequencies of solar p-modes, and the raw Qs are defined by the resolution bandwidths of the estimates, with values ranging from 100s to 1000s. Further, spectral peaks are consistently coherent across frequency due to non-stationarity, and frequently exhibit cyclostationarity at offset frequencies of ±0.5 and ±1 cpd.
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