标题： 外核对流的热化学模型与非均匀核幔边界热通量 显示英文标题

标题： Thermochemical models of outer core convection with heterogeneous core-mantle boundary heat flux

摘要： 地核中的热化学对流由内核结晶释放潜热和轻元素所驱动。 核心动力学中的一个关键问题是，在地核-地幔边界下方是否存在一个稳定层。 最近的核对流模拟，考虑到CMB的不均匀性，提出了局部稳定区域（或区域反转透镜，RILs），而不是一个全球层，使得稳定和不稳定区域可以共存。 在本研究中，我们考虑了一系列针对Ekman数（$E=10^{-5}$）的热、化学和热化学对流模型，其热和化学通量雷诺数分别为$\widetilde{Ra}_T=30-4000$和$\widetilde{Ra}_C=30-100000$，热和化学普朗特数分别为$Pr_T=1$和$Pr_\xi=10$。 对纯化学模型的分析显示，在CMB下方出现了轻元素积累（LEA），根据化学强迫的强度，这会导致极地附近的局部稳定区域或全球层。 即使热场完全不稳定，这些化学分层区域在我们的热化学模型中仍然存在。 添加不均匀的CMB热通量会导致由热分层驱动的RILs形成。 这些热化学模型中的稳定区域的位置、性质和形态各不相同，这取决于热对流还是化学对流占主导地位。 在所研究的参数范围内，这些RILs厚度约为100公里，它们的强度和厚度通常随着热驱动强度的增加而增加；它们对化学驱动强度的敏感性相对较低。 我们的模拟揭示了地球地核顶部可能存在的多种稳定区域和/或全球层，其厚度和强度具有地震上合理的范围，也可能在地磁观测中留下特征。 显示英文摘要

摘要： Thermochemical convection in Earth's outer core is driven by the crystallisation of the inner core that releases latent heat and light elements. A key question in core dynamics is whether a stable layer exists just below the core-mantle boundary. Recent core convection simulations, accounting for CMB heterogeneities, propose locally stable regions (or regional inversion lenses, RILs) rather than a global layer, allowing both stable and unstable regions to coexist. In this study, we consider a suite of numerical simulations of thermal, chemical, and thermochemical convection models focussed on Ekman number ($E=10^{-5}$) with thermal and chemical flux Rayleigh numbers $\widetilde{Ra}_T=30-4000$ and $\widetilde{Ra}_C=30-100000$, and thermal and chemical Prandtl numbers $Pr_T=1$ and $Pr_\xi=10$. Analysis of purely chemical models reveals light element accumulation (LEA) below the CMB, resulting in either locally stable regions near the poles or global layers, depending on the strength of chemical forcing. These chemically stratified regions persist in our thermochemical models even if the thermal field is fully destabilising. The addition of a heterogeneous CMB heat flux leads to the formation of RILs driven by thermal stratification. Stable regions in these thermochemical models have varying locations, properties, and morphologies depending on whether thermal or chemical convection dominates. In the investigated parameter range, these RILs are O(100 km) thick, and their strength and thickness generally increase with the strength of thermal driving; they are comparatively less sensitive to the strength of chemical driving. Our simulations reveal a diverse range of possible stable regions and/or a global layer at the top of Earth's core, with a seismically plausible range of thickness and strength, which may also have a signature in geomagnetic observations.