arXiv subjects

Wenbin Shen

Publications and source records attributed to Wenbin Shen.

7 recordsLinked to original sources

arXiv2026

Satellite gravity constraints on inner core viscosity and LLVPs density anomalies

Constraining the physical properties of Earth's deep interior, particularly the viscosity of the solid inner core and the density structure of large low-velocity provinces (LLVPs), remains a major challenge in geophysics. Here we develop a unified dynamical framework that combines mantle-inner core gravitational coupling (MICG) with torsional oscillations in the fluid outer core and show that their interaction can produce a distinct and testable geodetic signature. Guided by this prediction, we analyze satellite gravity observations together with independent corrections for surface mass variability. We identify a robust approximately 6-year signal in the Stokes coefficient Delta S22, while no corresponding stationary signal is detected in Delta C22. A signal with the same periodicity is independently detected in length-of-day variations (Delta LOD), and the two signals exhibit a near anti-phase relationship. Interpreting this coupled signature within the proposed framework allows us to constrain the inner core viscosity to approximately 4.6 (+/- 1.8) x 10^16 Pa s and the equatorial relief of the inner core boundary to a semi-axis difference of about 200 +/- 70 m. The inversion further indicates mean density anomalies of +5.5 (+/- 0.6) per mil at the base of LLVPs. These results indicate that satellite gravimetry provides a direct observational window into deep-Earth dynamics and the physical properties of Earth's deep interior.

physics.geo-ph↗

arXiv2026

Formulation of testing gravitational redshift based on Laser Time link between China Space Station and a ground station

This paper presents a high-precision gravitational redshift test using the China Space Station (CSS) Laser Time Transfer (CLT) system. We develop a comprehensive observation equation based on a c^{-3} order relativistic model for space-ground clock comparison. While the CSS optical clock system is currently in the orbital debugging phase, our simulation using actual CSS orbit data achieves a gravitational redshift verification precision of (1.8 \pm 47)*10^{-7} -- approximately one order of magnitude improvement over previous experiments. Our work represents the first application of laser-based time transfer for gravitational redshift verification at such precision, and the first use of the CSS CLT link for testing this fundamental aspect of General Relativity. Unlike microwave-based methods, our laser approach avoids ionospheric effects and first-order Doppler shifts. Residual analysis identifies tropospheric delay variations and atmospheric turbulence as the primary remaining uncertainty contributors. The achieved precision enables gravitational potential difference measurements with 0.1 m^2/s^2 precision -- offering new capabilities for both fundamental physics investigations and geodetic applications including intercontinental height transfer. This work establishes a new benchmark for high-precision tests of relativistic physics and demonstrates the transformative potential of space-based optical time transfer.

gr-qc↗

arXiv2024

Satellite observations reveal shorter periodic inner core oscillation

Detecting the Earth's inner core motions relative to the mantle presents a considerable challenge due to their indirect accessibility. Seismological observations initially provided evidence for differential/super-rotation of the inner core, but recently demonstrated a possibly about 70-year periodic oscillation. The contrasting results underscore the ongoing enigma surrounding inner core motion, leaving debates unresolved, including the precise oscillate period. In parallel to seismic observations, satellite geodesy has accumulated decades of global high-precision records, providing a novel avenue to probe inner core motions. Here, we detect an about 6-year oscillation from the gravitational field degree-2 order-2 Stokes coefficients derived from satellite observations, and find it has a unique phase correlation with the about 6-year signal in the Earth's length-of-day variations. This correlation is attributed to an inner core oscillation which is controlled by the gravitational coupling between the inner core and lower mantle (mainly due to the density heterogeneity of the two large low-velocity provinces; LLVPs). That is, we independently corroborate the inner core periodic oscillation, albeit with a significantly shorter period than previously suggested. Our findings demonstrate the dense layer of the LLVPs (mean density anomalies of about +0.9 percent at the bottom), consistent with inversions from tidal tomography and Stoneley modes. Furthermore, our research reveals equatorial topographic undulations of about 187 m at the inner core boundary.

physics.geo-ph↗

arXiv2023

Inner core static tilt inferred from intradecadal oscillation in the Earth's rotation

The geodynamic state of the inner core remains an enigma, encompassing the presence of a static tilt between the inner core and mantle. Following the experimental confirmation of an ~8.5yr signal in polar motion as the inner core wobble (ICW), a normal mode of the inner core, we report that the ~8.5yr oscillation contained in the length-of-day variations in the Earth's rotation has good phase consistency with it. Our analysis demonstrated a 0.17° static tilt of the inner core (more likely towards ~90°W) relative to the mantle, which is two orders of magnitude lower than the 10° assumed in certain geodynamic researches. This tilt is consistent with the assumption that the average density in the northwestern hemisphere of the inner core should be greater than that in the other regions. Besides, the observed ICW period (8.5yr) suggests a 0.52g/cm3 density jump at the inner core boundary.

physics.geo-ph↗

arXiv2022

Testing gravitational redshift based on microwave frequency links onboard China Space Station

In 2022 China Space Station (CSS) will be equipped with atomic clocks and optical clocks with stabilities of $2 \times 10^{-16}$ and $8 \times 10^{-18}$, respectively, which provides an excellent opportunity to test gravitational redshift (GR) with higher accuracy than previous results. Based on high-precise frequency links between CSS and a ground station, we formulated a model and provided simulation experiments to test GR. Simulation results suggest that this method could test the GR at the accuracy level of $(0.27 \pm 2.15) \times10^{-7}$, more than two orders in magnitude higher than the result of the experiment of a hydrogen clock on board a flying rocket more than 40 years ago.

astro-ph.IM↗

arXiv2020

New evidences for the fluctuation characteristic of intradecadal periodic signals in length-of-day variation

The intradecadal fluctuations in the length-of-day variation (dLOD) are considered likely to play an important role in core motions. Two intradecadal oscillations, with 5.9yr and 8.5yr periods (referred to as SYO and EYO, respectively), have been detected in previous studies. However, whether the SYO and the EYO have stable damping trends since 1962 and whether geomagnetic jerks are possible excitation sources for the SYO/EYO are still debated. In this study, based on different methods and dLOD records with different time span, we show robust evidences to prove that the SYO and the EYO have no stable damping trends since 1962, and we find that there is also a possible 7.6yr signal. To prove whether it is a periodic signal, we use the optimal sequence estimation method to stack 35 global geomagnetic records, the results also show an 7.6yr periodic signal which has an Y2,-2 spatial distribution, and it has a high degree of consistent synchronicity with the 7.6yr signal in dLOD. After confirming that the jerks have no special consistency with the peaks/valleys of the EYO/SYO, we confirm that the geomagnetic jerks seem to be related to sudden changes in the SYO/EYO time series and their excitation series; so we finally suggest that jerks are possible excitation sources of the SYO/EYO. Meanwhile, after using a deconvolution method, we estimate that the period P and quality factor Q of the SYO and the EYO are [P=5.85+/-0.06yr, Q larger than 180] and [P=8.455+/-0.17yr, Q larger than 350], respectively.

physics.geo-ph↗

arXiv2019

Formulation of a Triaxial Three-Layered Earth Rotation: I. Theory and Rotational Normal Mode Solutions

In this study, we formulated a triaxial three-layered anelastic Earth rotation theory con-sidering various core mantle couplings, including the pressure and gravitational couplings acting on the inner core by the outer core and mantle, the viscoelectromagnetic couplings between the outer core and mantle, and between the outer and inner cores. With this formulation, we provided four numerical solutions for the rotational normal modes, including the Chandler Wobble (CW), Free Core Nutation (FCN), Free Inner Core Nutation (FICN), an the Inner Core Wobble (ICW). The triaxiality led to increased periods for the CW and ICW of about 0.01 and 0.35 mean solar days (d), respectively. The mantle anelasticity and ocean tide induced dissipations were mainly responsible for the CW, but contributed little to the FCN, while the viscoelectromagnetic coupling induced dissipations were mainly responsible for the FCN, FICN, and ICW. By investigating different types of couplings, we found that pressure coupling played the dominant role in prograde FICN, while viscoelectromagnetic or gravitational couplings either alone, or together gave rise to retrograde FICN. On the other hand, the ICW period varied extensively from 130 d to 21 yr under different core mantle coupling conditions.

physics.geo-ph↗