Comment on "Fingerprint structure PC 1 geomagnetic pulsations"

• Published in: Geophysical research letters Vol. 14; no. 11; pp. 1178 - 1179
• Main Author: Fraser-Smith, A. C.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.11.1987; American Geophysical Union
• Subjects: Earth, ocean, space; Exact sciences and technology; External geophysics; Magnetic pulsations; Physics of the magnetosphere; Fine structure; Pc 1 micropulsation; Plasma resonance
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/GL014i011p01178

Sato et al. [1987] recently drew attention to a new form of Pc 1 pulsations, which they refer to as ‘fingerprint structure’ Pc 1 pulsations because of their distinctive appearance in frequency‐time (f‐t) spectrograms. The new pulsations were observed on moderately high latitude geomagnetic field lines (L≈6) and the authors suggested that the considerable number of spectral lines and their constant frequency separation might provide evidence for non‐linear effects in the Pc 1 pulsation generation region. It is suggested here, on the contrary, that the fine frequency structure is not a non‐linear effect but is simply a manifestation of field line resonances of the kind suggested by Fraser‐Smith [1967].