50-day Oscillation of Length-of-day Change |
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| Authors: | Lihua Ma Yanben Han Dechun Liao |
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| Institution: | 1. National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China
2. Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai, 200030, China
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| Abstract: | Variations of Earth’s rotation rate (length-of-day, LOD) occur over a wide range of time scales from a few hours to the geological age. Studies showed that the 50-day fluctuation exists in LOD change. In the present paper, the authors use wavelet technique to study the 50-day oscillation in LOD series. Temporal variations of the oscillation are presented in this work. After analyzing the axial component of atmospheric angular momentum (AAM) and oceanic angular momentum (OAM), the 50-day periodic signal is also found in atmospheric and oceanic motion with remarkable time-variation. Meanwhile, the 50-day oscillation of the axial AAM is in good consistence with that of LOD change. This suggests that the 50-day oscillation of LOD change is mainly excited by the axial AAM. Possible origin of the oscillation for Earth system is discussed in the end of this paper. |
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