Orbital influence on Earth's magnetic field: 100,000-year periodicity in inclination.
A continuous record of the inclination and intensity of Earth's magnetic field, during the past 2.25 million years, was obtained from a marine sediment core of 42 meters in length. This record reveals the presence of 100,000-year periodicity in inclination and intensity, which suggests that the magnetic field is modulated by orbital eccentricity. The correlation between inclination and intensity shifted from antiphase to in-phase, corresponding to a magnetic polarity change from reversed to normal. To explain the observation, we propose a model in which the strength of the geocentric axial dipole field varies with 100,000-year periodicity, whereas persistent nondipole components do not.
Yamazaki
Toshitsugu
T
Institute for Marine Resources and Environment, Geological Survey of Japan, AIST, Tsukuba 305-8567, Japan.
Oda
Hirokuni
H