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On the Isogonic Lines Over the East Siberia and Japan(II)
The distribution of the magnetic force over the south hemisphere is rather simple, while over the north hemisphere, it is more complex, owing to two total intensity maximums, the Siberian one σ(M.P in the first report), and the North American one ν, whose positions in 1975 were approximately 60°N, 110°E, and 56°N, 94°W respectively.
The two maximums σ and ν seems to cause the distribution of the Iso-Y-component lines, separating them into four closed line groups. The intersection points of these lines with the Iso-X-component lines construct isogonic lines of various forms，among them the Iso-Y-component lines over the east Siberia and Japan only forms closed curve of oval shape which is characteristic of isogonic line of this region. The center of it is found always more northward than that of the associated circular Iso-Y-component lines, and the center of the former progress northward as west declination in this region increase.
In recent years, in spite of the force of the North Magnetic Pole and the North American Maximum ν are almost constant or somewhat weaker becoming, though, the intensity in the Siberian Maximum region σ is increasing taking with west declination increase in this area.
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