Dynamics of three-layer convection in a two-dimensional spherical domain with a growing innermost layer: Implications for whole solid-earth dynamics
Dynamics of three-layer convection in a two-dimensional spherical domain with a growing innermost layer: Implications for whole solid-earth dynamics
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DOI：
10.1063/1.5049703
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发表时间：
2018-09
影响因子：
4.6
通讯作者：
Masaki Yoshida
中科院分区：
文献类型：
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作者：
Masaki Yoshida
我已经进行了数值模拟的热对流与高粘度的最外层（HVL），低粘度的中间层（LVL），和高粘度的最内层（IML）随着时间的增长在2-D球形域。结果表明，与无内模层的模型相比，内模层随时间增长时，层积体的平均温度显著降低，层积体的均方根速度波动较大。这一结果表明，IML的形成有效地冷却了LVL。然而，增长的IML的存在几乎不影响的大小和空间格局的热流在HVL-LVL界面和对流模式的HVL。此外，由于来自LVL-IML界面的基底加热，IML的增长延长了LVL对流的横向尺度。目前的数值结果意味着，在整个地球历史中，不断增长的内核（对应于该模型中的IML）可能几乎不会影响地幔（HVL）的对流模式和从外核逃逸的热流（即，LVL）通过核幔边界（即，HVL-LVL接口）。先前的地球发电机模拟表明，核幔边界下温度的横向热不均匀性增强了外核的地磁场。目前的数值结果可能表明，不断增长的内核在整个地球的历史促进了强烈的横向热不均匀性和加强的地磁场。我已经进行了数值模拟的热对流与高粘度的最外层（HVL），低粘度的中间层（LVL），高粘度的最内层（IML）随时间增长的2-D球形域。结果表明，与无内模层的模型相比，内模层随时间增长时，层积体的平均温度显著降低，层积体的均方根速度波动较大。这一结果表明，IML的形成有效地冷却了LVL。然而，增长的IML的存在几乎不影响的大小和空间格局的热流在HVL-LVL界面和对流模式的HVL。此外，由于来自LVL-IML界面的基底加热，IML的增长延长了LVL对流的横向尺度。目前的数值结果意味着，在整个地球历史中，不断增长的内核，这对应于该模型中的IML，可能几乎不会影响对流模式。
I have performed numerical simulations of thermal convection with a highly viscous outermost layer (HVL), low-viscosity middle layer (LVL), and highly viscous innermost layer (IML) growing with time in a 2-D spherical domain. The results show that the average temperature of the LVL significantly decreases and the root-mean-square velocity of the LVL fluctuates significantly when the IML grows with time, compared to the model without the growing IML. This result suggests that the formation of the IML cools the LVL effectively. However, the existence of the growing IML barely affects the magnitude and spatial pattern of the heat flow at the HVL–LVL interface and the convection pattern of the HVL. In addition, the growing IML lengthens the lateral scale of the LVL convection owing to the basal heating from the LVL–IML interface. The present numerical results imply that the growing inner core, which corresponds to the IML in this model, throughout the Earth’s history may barely affect the convection pattern of the mantle (HVL) and the heat flow escaping from the outer core (i.e., LVL) to the mantle via the core–mantle boundary (i.e., the HVL–LVL interface). A previous geodynamo simulation suggested that the lateral thermal heterogeneity of the temperature just under the core–mantle boundary strengthens the geomagnetic field in the outer core. The present numerical results may suggest that the growing inner core throughout the Earth’s history facilitates the strong lateral thermal heterogeneity and strengthens the geomagnetic field.I have performed numerical simulations of thermal convection with a highly viscous outermost layer (HVL), low-viscosity middle layer (LVL), and highly viscous innermost layer (IML) growing with time in a 2-D spherical domain. The results show that the average temperature of the LVL significantly decreases and the root-mean-square velocity of the LVL fluctuates significantly when the IML grows with time, compared to the model without the growing IML. This result suggests that the formation of the IML cools the LVL effectively. However, the existence of the growing IML barely affects the magnitude and spatial pattern of the heat flow at the HVL–LVL interface and the convection pattern of the HVL. In addition, the growing IML lengthens the lateral scale of the LVL convection owing to the basal heating from the LVL–IML interface. The present numerical results imply that the growing inner core, which corresponds to the IML in this model, throughout the Earth’s history may barely affect the convection pattern o...