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The Spectral Power Density and Shadowing Function of a Glacial Microrelief at the Decimetre Scale

  • J.-P. Benoist (a1)

Abstract

Longitudinal profiles of roches moutonnées have been measured once every centimetre over a total length of more than 100 m. Only wavelengths in the range 3.6 cm < λ < 40 cm have been kept and analysed. Levels and their slopes have a symmetrical, non-Gaussian distribution. The spectral power density varies roughly as γ 0 ν–n (ν ═ wavenumber ═ 1/λ); n being the same for all the profiles (n ═ 2.36) and γ 0 being dependent on the studied area. No significant difference has been found for the shadowing function of the different studied areas. It differs consistently from Smith’s theoretical function.

Résumé

On a mesurétous les centimètres, plus de 100 m de profils sur des roches moutonnées. Seules les longueurs d’onde λ entre 3,6 cm et 40 cm ont été analysées. Les ordonnées d’une part et leurs pentes d’autre part, ont une distribution symétrique non gaussienne. La densité spectrale de puissance décroît sensiblement comme γ 0 ν–n (ν ═ fréquence ═ 1/λ); n est le même pour tous les profils (n ═ 2,36) γ 0 diffère suivant la zone étudiée. Il n’y a pas de différence significative pour le fonction d’éclairement calculée pour les différentes zones. Elle diffère de façon sensible de la courbe théorique calculée par Smith.

Zusammenfassung

Längs-profile über Rundhöcker mit einer Gesamtlänge von mehr als 100 m wurden Zentimeter für Zentimeter eingemessen. Festgestellt und analysiert wurden nur Wellenlängen im Bereich 3,6 cm < λ < 40 cm. Die Ordinaten und ihre ersten Ableitungen haben eine symmetrische, nicht-normale Verteilung. Das Leistungsspektrum schwankt annähernd mit γ 0 ν–n (ν ═ Frequenz ═ 1/λ), wobei n für alle Profile denselben Wert (n ═ 2,36) besitzt, während γ 0 verschieden ist. Für die Fensterfunktion der versehiedenen untersuchten Gebiete wurde kein signifikanter Unterschied festgestellt; sie weicht jedoch konsequent von Smith’s theoretischem Wert ab.

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References

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The Spectral Power Density and Shadowing Function of a Glacial Microrelief at the Decimetre Scale

  • J.-P. Benoist (a1)

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