Induction in a transatlantic cable at periods between 20 minutes and one day

Abstract
Power spectral anaylses are presented of the voltage fluctuations in a transatlantic cable on two days of moderate geomagnetic activity and four days of magnetic quiet. The voltage fluctuations with periods from about twenty minutes to a day are predominantly of geomagnetically‐induced origin, with similar peaks often found in the geomagnetic and voltage spectra. The voltage spectral power Sv at a given frequency f can be expressed in terms of the horizontal field spectral power SH as βSHfγ.