| Summary: | The dynamic topography of the core-mantle boundary (CMB) provides important constraints on dynamic processes in the mantle and core. However, inferences onCMBtopography are complicated by uneven data coverage and strong lower mantle heterogeneity. Particularly, a trade-off exists with density variations, which ultimately drive mantle flow and are vital for determining the origin of mantle structures. Here, I review existing models of CMB topography and lower mantle density, focusing on seismological constraints. While most density models image two areas of dense anomalies beneath Africa and the Pacific, their exact location and relationship to seismic velocity structure differs. CMB topography strongly influences the retrieved density structure, helping to resolve differences between existing studies. Current CMB topography models vary both in pattern and amplitude, with a discrepancy between body-wave and normal-mode models. As existing models feature elevated topography below the Large-Low-Velocity Provinces (LLVPs), geodynamic predictions indicate that very dense compositional anomalies may currently be ruled out as possibility. To achieve a similar consistency as observed in S-wave and P-wave tomography models, future studies should develop models of CMB topography consistent with body-wave, normal-mode and geodetic data. This will help to break existing trade-offs with lower mantle density, thus aiding in narrowing down possible explanations for the LLVPs and providing additional insights into mantle dynamics.
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