本邦近海の磁針偏差について(日本航海学会第24回講演会)

概要

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Since 1912, the magnetic survey of the whole Japan and the adjacent areas of Japan was carried out by the Japanese Hydrographic Office. The results of these magnetic surveys were published as the magnetic chart of the adjacent seas of Japan. In construction of the magnetic chart, magnetic variation was calculated from the following empirical formulae on geographical distribution which is expressed by the quadratic function of latitude ψ and longitude λ, δ=δ+aλ+bψ+cλψ+dλ^2+eψ^2. From July 11 to 20, 1960, the 1st magnetic survey at sea was carried out with the magnetic compass for navigation by the survey ship "Takuyo" of the Hydrographic Office around the west coast in Hokkaido and Siriyamisaki. From the magnetic survey, it was found following results. 1) Departure of the observed magnetic variation at sea from the empirical formulae are considered to be less than ± 1°. Therefore, the magnetic chart constructed by Japanese Hydrographic Office is correct for navigation. 2) It has been reported by navigator that there are local magnetic disturbances at several areas in Hokkaido, but it was found that there are no local disturbance more than ± 1°from the results of the magnetic survey for navigation.
社団法人日本航海学会の論文
1961-02-25