Anelasticity and Lateral Heterogeneities in Earth's Upper Mantle: Impact on Surface Displacements, Self‐Attraction and Loading, and Ocean Tide Dynamics

Abstract

Ocean tide loading refers to the periodic redistribution of water masses due to tidal forcing, which causes deformations of the solid Earth and perturbations of the gravity field. The resulting elastic and gravitational responses of the solid Earth are termed "load tides" (e.g., Farrell, 1972). Load tides at the Earth's surface can be described as vertical displacement, horizontal displacement and the gravitational potential increment. In ocean areas, the geoid undulation relative to the vertical displacement is specified by the "self-attraction and loading" (SAL: e.g., Ray, 1998) elevation. Load tides are as important as body tides (e.g., Takeuchi, 1950) in making up the total tide of the solid Earth induced by the astronomical forces. On the other hand, the SAL potential (SAL elevation times surface gravity) induces secondary barotropic accelerations that influence ocean tide dynamics, and, as a result, their consideration is a necessity for generating an accurate ocean

The Influence of Sediments, Lithosphere and Upper Mantle (Anelastic) With Lateral Heterogeneity on Ocean Tide Loading and Ocean Tide Dynamics

“…The M 2 ‐results can be seen in the light of the results of Huang et al. (2021) where similar behavior was reported.…”

“…seen that, the anelastic upper mantle pertaining to Lyon-3Dae causes a displacement increase for all three tidal loads, most significantly in open ocean areas and coastal areas where tidal amplitudes are large and seismic attenuation is high, which is in agreement with the findings of Huang et al (2021). For inland continents away from coastal regions, however, displacements decrease, which is consistent with the findings of Experiments 1 and 2 of Huang et al (2021). In addition, despite of the increase of shear modulus reduction with the increasing tidal period, we see a decrease of the anelastic impact on vertical OTL displacement from the order of 1-0.01 mm, due to the decreasing ocean tide amplitude.…”

“…Also the pure 3D-effect couples more strongly to the oceanic eigenmodes as semidiurnal amphidromic systems take place on shorter spatial scales that are thus closer to the scales of the pure 3D-effect patterns. The M 2 -results can be seen in the light of the results of Huang et al (2021) where similar behavior was reported.…”

“…However, there are several aspects missing in the 3D anelastic earth models of Huang et al. (2021) as well as the 1D elastic/anelastic earth models used in other OTL studies, which include 3D sediments, oceanic and continental lithosphere and anelasticity for longer‐period OTL such as the K 1 and M f tides. This study will focus on these three aspects of the solid Earth and show their impact on OTL and OTD.…”

“…The Influence of Sediments, Lithosphere and Upper Mantle (Anelastic) With Lateral Heterogeneity on Ocean Tide Loading and Ocean Tide Dynamics heterogeneity on self-attraction and loading (SAL) elevation, and more importantly, they showed that this impact has a feedback to OTD with an root-mean-square (RMS) of above 5 mm in specific coastal areas. However, there are several aspects missing in the 3D anelastic earth models of Huang et al (2021) as well as the 1D elastic/ anelastic earth models used in other OTL studies, which include 3D sediments, oceanic and continental lithosphere and anelasticity for longer-period OTL such as the K 1 and M f tides. This study will focus on these three aspects of the solid Earth and show their impact on OTL and OTD.…”