Long-term seafloor geomagnetic station in the northwest Pacific: A possible candidate for a seafloor geomagnetic observatory

概要

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For two years, geomagnetic variations have been measured at the seafloor in the northwest Pacific. The seafloor data consist of the geomagnetic vector field measured by a three-component fluxgate magnetometer and the absolute scalar total force measured by an Overhauser (1953) magnetometer with attitude measurements for both orientation and tilt. Using the attitude data, the geomagnetic data at a site in the northwest Pacific (41°06′08″N, 159°57′47″E, -5580 m), hereafter referred to as NWP, were converted into the same reference frame as land and satellite measurements. Short-period variations of the converted vector data were examined by Hamano's (2002) global time domain analysis method, which showed compatibility of the seafloor geomagnetic observatory data with the existing land observatory network. The smooth and gradual change of the Earth's main field (i.e., the geomagnetic secular variation) was also found consistent with those predicted by the latest International Geomagnetic Reference Field (IGRF-10; IAGA, 2005) and by Orsted Satellite (Olsen, 2002) for not only the scalar field but also the vector field. This means that observation of the geomagnetic vector secular variation is now feasible on the seafloor.
公益社団法人日本地震学会、地球電磁気・地球惑星圏学会、特定非営利活動法人日本火山学会、日本測地学会、日本惑星科学会の論文