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The Geomagnetic Variations of Daily, Monthly and Annual Means and World-Wide Distribution of Daily Mean(Part 1)
In the present paper the author investigates various characteristics of geomagnetic long term means, such as daily, monthly and annual means, and world-wide distributions of daily mean for the purpose of clarifying statistically the influcnce of the external field upon the geomagnetic mean values and of preparing some basic information about the geomagnetic fields due to the inner part of the earth and their secular variation.
The effects of the disturbances of the external field which is expressed by the daily sum of Kp-indices appear as the decrement of about 20 γ in the horizontal intensity(H), westward change of 1' in the declination (D) and irregular variation less than 3γ in the vertical intensity (Z), in Japan and her vicinity.
In the variations of daily mean values at Kakioka, Memambetsu and Kanoya in Japan, H, D and Z are closely correlated each other and their deviations from the regression lines are at most 士4 γ,士0.4' and 土5γ respectively. These values should be taken into consideration in an investigation of the internal geomagnetic field.
The mean recovery rates for the changes of daily mean values due to geomagnetic storm at Kakioka are about 7-4γ/day increase for ssc and 2γ/day increase for sg in H, 1-0.8'/day eastwards for ssc and 0.3'/day for sg in D, and rate in Z is irregular and small amount of about one fifth of H.
In the similar way the changes of monthly and annual mean values at observatories in Japan are examined for the period from 1952 to 1962. The monthly and annual mean values are also affected by external field, and those amount are about 20γof decrease in H, westward change of one minute in D and less than 3γ in Z similarly to the daily mean values.
In the variation, components H, D and Z are closely correlated each other and their deviations from the regression lines are at most 士 2-3γ, 士0.3-0.4'and 土3-4 γ respectively for the monthly mean, and 土2-3γ, 土0.2-0.4' and 士1 γ respectively for the annual mean. These deviations are a little larger than the accuracies of the observations and seem to be attributed to the characters of the inner part of the earth.
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