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[SEM15-P01] Magnetic Charts of Japan for the epoch 2020.0
Keywords:Magnetic field modeling, Geomagnetism, Main field, Magnetic declination, Principal component analysis, Magnetic charts
The Geospatial Information Authority of Japan (GSI) has been conducting geomagnetic surveys and investigating the geomagnetic distribution and its secular variation in and around Japan by their magnetic surveys around all over Japan since about 1950. Magnetic declinations, a component of the field which is necessary for adjusting a difference between true north and magnetic north, especially needs to be regularly revised. Accordingly, GSI regularly updates the main field model of Japan in a form of chart.
Recent GSI’s secular variation model derived from the principal component analysis, which applies to observations recorded by ground observatories in Japan. The main field model of Japan is derived by adding this secular variation model to the results of geomagnetic survey at GSI’s geomagnetic stations which consists of about 850 points. GSI recently updates magnetic charts every 5 years since 2010.0 model as with other models or maps such as IGRF or WMM, and the magnetic charts of Japan for epoch 2020.0 was released by GSI in early 2022 as the latest version of the main field model of Japan (see Figure).
The magnetic declinations for epoch 2020.0 shows westerly deflection about 9.7, 5.5 and 7.8 degrees in Hokkaido, Okinawa and Japan respectively. Then, the westward declination for epoch 2020.0 has increased approximately 0.3 degree in Japan compared with the one for epoch 2015.0.
Recent GSI’s secular variation model derived from the principal component analysis, which applies to observations recorded by ground observatories in Japan. The main field model of Japan is derived by adding this secular variation model to the results of geomagnetic survey at GSI’s geomagnetic stations which consists of about 850 points. GSI recently updates magnetic charts every 5 years since 2010.0 model as with other models or maps such as IGRF or WMM, and the magnetic charts of Japan for epoch 2020.0 was released by GSI in early 2022 as the latest version of the main field model of Japan (see Figure).
The magnetic declinations for epoch 2020.0 shows westerly deflection about 9.7, 5.5 and 7.8 degrees in Hokkaido, Okinawa and Japan respectively. Then, the westward declination for epoch 2020.0 has increased approximately 0.3 degree in Japan compared with the one for epoch 2015.0.