Memoirs of the Kakioka Magnetic Observatory Vol.01 No.04， p.32, December, 1938

On the Times of Sudden Commencements of Magnetic Storms and Magnetic Pulsations

Imamiti, S.

Abstract

 The absolute times of beginning of abrupt magnetic disturbances of Horizontal intensity were observed at Kakioka, Toyohara, and Tsingtau with more precise manner than hitherto used, and with improved magnetograph, which are all the same pattern specially made for the purpose of this investigation. For the magnetograph 12 mm.-15 mm. of the absissa-scale corresponds to a time-interval of one minute or 36-48 times longer than ordinary one. Eight abrupt magnetic storms are observed from October, 1932 to December, 1933, of which fives storms were available. The results are as follows:
  At Kakioka and Tsingtau, the magnetic storms were observed every case 6 - 10 seconds earlier than at Toyohara, and this range of time retardation seems to depend on the types of commencement to storms. If the magnetic impulse traveled, the velocity of propagation in the north hemisphere would be 100-200 km/sec from lower magnetic latitude to higher.
  The time of occurrence of pulsation (Elementalwellen) are also compered, and the following result is obtained.
  Pulsations at those three observatories occur simultaneously in one second.
  Errers due to variometers used are discussed.

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