Anelasticity of the lower mantle inferred from the pole and lunar monthly tides using global DORIS coordinate time series

Abstract

Global mantle anelasticity reflects the dissipation mechanism of Earth's interior structure. Nevertheless, there is still an ongoing debate regarding the anelastic properties of the lower mantle (660–2900 km depth). Advancements in data accuracy and record expansion have enabled geodetic technology to offer novel methods for determining the anelastic properties of the lower mantle. This study utilizes an optimal sequence estimation method to obtain tidal Love numbers based on Doppler Orbitography and Radio-positioning Integrated by Satellite (DORIS) coordinate time series. Love number h2,1 of pole tides at the 433-day Chandler wobble (CW) is 0.6280 (±0.0040) - 0.0127 (±0.0037)i. Love numbers h2,0 and l2,0 of zonal body tides at the 27.55-day Lunar month (Mm) are 0.6137 (±0.0034) - 0.0032 (±0.0035)i and 0.0886 (±0.0009) - 0.0015 (±0.0007)i, respectively. In light of these estimates, we infer the dispersion and dissipation parameters fr(ω) and fi(ω), respectively, by employing the power-law absorption band model with a reference period of 200 s and determine the weighted-mean value of the frequency exponent α as 0.210 ± 0.023 that links closely related to the effective viscosity. For comparison, we calculate the corresponding values from a laboratory-based extended Burgers model and show that the anelasticity parameter functions appear more compact but still support the conclusion that α varies between 0.1 and 0.3. Our results could serve as a practical constraint on the anelastic behavior of the lower mantle, contributing to a better understanding of the overall dynamics of the Earth's deep interior.