Memoirs of the Kakioka Magnetic Observatory Vol.20 No.01， p.17, March, 1983

Characteristics of the Geomagnetic Storms based on the Statistical Analysis

Nagai, M.

Abstract

 Some characteristics of the geomagnetic storms are statistically investigated by using the data observed at Kakioka(1924-81), Memambetsu(1958-81) and Kanoya(1958-81).
  Furthermore, similar examinations are carried out for the IAGA's data of ssc during the period from 1868 to 1981.
  Remarkable results are as follows:
 
  1) Since the sudden commencement is a world-wide phenomenon, there should be no local time dependence of the occurrence frequency of SC's. However, there is an apparent diurnal variation at Kakioka showing a tendency for an early morning minimum of occurrence of SC's. This observational result is simi1ar to the diurnal variation for the IAGA's data.
 
  2) Magnitude of SC's(ΔH) grows at the night-time, and diminishes at 8-10 hours in local time. Amplitude of diurnal variation of the ΔH at Memambetsu is larger than those at Kakioka and Kanoya. These results suggest that the electric current of Ds(SC) sometimes extends to lower latitude, and makes a cause of local time dependence of the SC magnitude, even in middle and low latitudes.

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