On the 60-year signal from the core |
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| Authors: | P H Roberts Z J Yu C T Russell |
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| Institution: | 1. Institute of Geophysics and Planetary Physics , University of California , Los Angeles, CA 90049, USA robb@math.ucl.ac.uk;3. Wilshire Associates Inc, 1299 Ocean Avenue, Suite 700, Santa Monica, CA 90401, USA;4. Institute of Geophysics and Planetary Physics , University of California , Los Angeles, CA 90049, USA |
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| Abstract: | The decadal variation in the length of day and in the Earth's magnetic field is analyzed by empirical mode decomposition (EMD). The existence of a periodicity of about 60-years in the Earth's angular velocity has often been inferred and is confirmed here, with a new estimate of approximately 62 years. The existence of a similar periodicity in the geomagnetic field has been controversial. From the time series analyses presented here of the magnetic declination at 10 observatories, it is concluded that a geomagnetic periodicity of about 62?±?3 years does exist. A similar analysis of the magnetic inclination at five observatories gives a period of 58?±?5 years. The declination data from four observatories is found to correlate with the length of day signal, with a correlation coefficient of approximately 0.6. |
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| Keywords: | Length of day (LoD) Geomagnetic secular variation Torsional oscillations |
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