...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Earth, planets and space: EPS >Mantle-driven geodynamo features-effects of post-Perovskite phase transition
【24h】

Mantle-driven geodynamo features-effects of post-Perovskite phase transition

机译：地幔驱动的地球动力学特征-钙钛矿后相变的影响

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Exploring the impact of the heterogeneous lower mantle on the geodynamo requires knowledge of the heat flux anomaly across the core-mantle boundary. Most studies so far used a purely thermal interpretation of seismic Shear wave anomalies to assign heterogeneous heat flux boundary conditions oil numerical dynamo models. ignoring phase transition or compositional origins. A recent study of mantle convection (Nakagawa and Tackley, 2008) provides guidelines to include such non-thermal effects. Here we Construct maps of heat flux across the core-mantle boundary based oil a lower mantle tomography model (Masters et al.. 2000) with a combined thermal and post-Perovskite phase transition interpretation. We impose these patterns as cuter boundary conditions Oil numerical dynamo Simulations and study the impact of accounting for post-Perovskite effects on the long-term time-average properties of the dynamo. We then compare our results with geophysical observations. We find in all cases that surface downwellings associated with cyclones concentrate intense non-axisymmetric magnetic flux at high-latitudes, the Surface flow contains a large anticlockwise vortex at mid-latitudes of the Southern hemisphere, and the inner boundary buoyancy flux is dominated by a Y-2(0) pattern. Boundary-driven time-average surface flow with some equatorial asymmetry is organized in the shelf by quasi-axial convective rolls that extract more buoyancy from low-latitudes of the inner-boundary. These positive inner boundary buoyancy flux structures are found at low-latitudes of the northern hemisphere, in sonic places due 10 Cyclonic flow at mid-latitudes of the southern hemisphere connecting with higher latitude cyclonic flow in the northern hemisphere. Accounting for post-Perovskite effects improves the recovery of several geodynamo observations. including the Atlantic/Pacific hemispherical dichotomy in core flow activity, the single intense paleomagnetic field structure in the southern hemisphere, and possibly the m = 1 dominant mode of inner-core seismic heterogeneity.
机译：要探究非均质下地幔对大地发电机的影响，需要了解穿过岩心-地幔边界的热通量异常。迄今为止，大多数研究仅使用地震剪切波异常的纯热解释来分配非均质热通量边界条件油数值发电机模型。忽略相变或成分起源。最近对地幔对流的研究（Nakagawa和Tackley，2008年）提供了包括此类非热效应的指南。在这里，我们通过结合热学和钙钛矿后相变解释的下地幔层析成像模型（Masters等，2000）构建了穿过地幔边界的油的热通量图。我们将这些模式作为边界条件强加给石油数值发电机模拟，并研究考虑钙钛矿后效应对发电机长期时间平均特性的影响。然后，我们将结果与地球物理观测结果进行比较。我们发现，在所有情况下，与旋风分离器相关的表面下降流都在高纬度集中了强烈的非轴对称磁通量，地表流在南半球中纬度处包含一个大的逆时针涡旋，而内部边界浮力通量由一个Y-2（0）模式。边界驱动的具有一定赤道不对称性的时间平均表面流是通过准轴向对流辊在架子上组织的，准轴向对流辊从低纬度的内部边界抽取更多的浮力。这些正的内部边界浮力通量结构在北半球的低纬度，在声波处发现，这是由于南半球的中纬度有10个旋风流与北半球的较高纬度的旋风流有关。钙钛矿后效应的考虑改善了几项大地发电机观测的恢复。包括核心流动活动中的大西洋/太平洋半球二分法，南半球的单个强古磁场结构，以及内核地震非均质性的m = 1主导模式。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号