引入地轴进动的地球发电机模型数值模拟

王正涛, 詹文臻, 丁嘉威, 刘美琴

王正涛, 詹文臻, 丁嘉威, 刘美琴. 引入地轴进动的地球发电机模型数值模拟[J]. 武汉大学学报 ( 信息科学版), 2022, 47(4): 501-507. DOI: 10.13203/j.whugis20190298
引用本文: 王正涛, 詹文臻, 丁嘉威, 刘美琴. 引入地轴进动的地球发电机模型数值模拟[J]. 武汉大学学报 ( 信息科学版), 2022, 47(4): 501-507. DOI: 10.13203/j.whugis20190298
WANG Zhengtao, ZHAN Wenzhen, DING Jiawei, LIU Meiqin. Numerical Simulation of Dynamo Model with the Earth's Axis Precession[J]. Geomatics and Information Science of Wuhan University, 2022, 47(4): 501-507. DOI: 10.13203/j.whugis20190298
Citation: WANG Zhengtao, ZHAN Wenzhen, DING Jiawei, LIU Meiqin. Numerical Simulation of Dynamo Model with the Earth's Axis Precession[J]. Geomatics and Information Science of Wuhan University, 2022, 47(4): 501-507. DOI: 10.13203/j.whugis20190298

引入地轴进动的地球发电机模型数值模拟

基金项目: 

国家自然科学基金 41974007

国家自然科学基金 41774019

国家自然科学基金 41474018

国家自然科学基金 41274032

地球观测与时空信息科学国家测绘地理信息局重点实验室经费 201812

详细信息
    作者简介:

    王正涛, 博士, 教授, 主要从事固体地球物理学研究。ztwang@whu.edu.cn

  • 中图分类号: P223

Numerical Simulation of Dynamo Model with the Earth's Axis Precession

Funds: 

The National Natural Science Foundation of China 41974007

The National Natural Science Foundation of China 41774019

The National Natural Science Foundation of China 41474018

The National Natural Science Foundation of China 41274032

the Open Research Fund Program from Key Laboratory of Earth Observation and Geospatial Information Science of NASG 201812

More Information
    Author Bio:

    WANG Zhengtao: WANG zhengtao, PhD, professor, majors in solid geophysics.E-mail: ztwang@whu.edu.cn

  • 摘要: 在地球外核磁流体发电机数值模拟研究中,与地轴进动相关的庞加莱力通常视其影响极小而在求解发电机方程组中将其忽略,但实际上地轴进动的周期相对地球磁场的倒转周期来说仍是一个值得考虑的项。基于地球发电机数值模拟基准模型,通过引入周期为25 960 a的地轴进动速度,比较分析不同埃克曼数和瑞利数参数组合模型中地轴进动对发电机数值模型的作用。结果表明,地轴进动使得球壳磁流体的动能及磁能波动稳定在一个较原始模型更小的范围内,但增大球壳磁流体的环向动能10%~20%以上,这导致磁场西向漂移速率明显加快;通过比较各模型间的核-幔边界磁场强度和磁雷诺数,发现地轴进动项的引入使得磁流体的能量更倾向于向动能转换;通过比较核-幔边界的偶极性,发现地轴进动项的引入会降低磁流体发电机数值模型的偶极性,但对于所选的原始模型,偶极性的减小程度还不足以使其成为非类地发电机模型。通过数值模拟研究,发现地轴进动项的加入很可能会导致埃克曼数量级较小的类地发电机模型变为多极子主导的发电机模型,因此,在更为准确的磁流体发电机数值模拟研究中,必须考虑地轴进动项。
    Abstract:
      Objectives  The Poincaré force related to the precession of Earth's axis is usually omitted in the solution of the dynamo equations as its effects are minimal. But in fact, the period of Earth's axial precession is still a term that is worth considering compared to the period of Earth's magnetic field reversal.
      Methods  This paper compares and analyzes different dynamo models with Ekman number and Rayleigh number by introducing Earth's axis precession velocity with a period of 25 960 years.
      Results  It is found that Earth's axial precession stabilizes the kinetic energy and magnetic energy fluctuation of spherical shell magnetic fluid in a smaller range than the benchmark dynamo, and increases the toroidal kinetic energy of spherical shell magnetic fluid by more than 10%-20%, which leads to significantly accelerated westward drift rate of the magnetic field. Based on the magnetic field strength and magnetic Reynolds number at the core-mantle boundary of those dynamos, it is found that the introduction of the precession item of Earth's axis makes magnetic energy more tend to kinetic energy conversion. And by comparing the core-mantle boundary dipolarity, it is found that the introduction of the precession item will reduce the dipolarity. But for the dynamos in this article, the influence is not strong enough to make it become less Earth-like.
      Conclusions  From the comparison and analysis of the dynamo models, the introduction of Earth's axis precession would possibly change the dynamo model with a small Ekman number to a multipole dominant dynamo model. It can be inferred that the term of Earth's axis precession should be considered in more precise research of the numerical dynamo simulation for more.
  • 致谢: 本文使用的MagIC代码由Thomas Gastine博士提供,黄曦博士和林玉峰副教授在使用MagIC代码中提供了帮助;本文的数值计算得到了武汉大学超级计算中心和武汉大学测绘学院网络与数据处理中心的计算支持和帮助,在此一并表示感谢。
  • 图  1   模型1、2在6个粘性时间尺度内的外核极向动能

    Figure  1.   Poloidal Kinetic Energy of the Outer Core Calculated by Models 1 and 2 in 6 Viscous Time Scales

    图  2   模型3、4在6个粘性时间尺度内的外核极向动能

    Figure  2.   Poloidal Kinetic Energy of the Outer Core Calculated by Models 3 and 4 in 6 Viscous Time Scales

    图  3   模型1、2在6个粘性时间尺度内的外核环向动能

    Figure  3.   Toroidal Kinetic Energy of the Outer Core Calculated by Models 1 and 2 in 6 Viscous Time Scales

    图  4   模型3、4在6个粘性时间尺度内的外核环向动能

    Figure  4.   Toroidal Kinetic Energy of the Outer Core Calculated by Models 3 and 4 in 6 Viscous Time Scales

    图  5   模型1、2在6个粘性时间尺度内的外核极向磁能

    Figure  5.   Poloidal Magnetic Energy of the Outer Core Calculated by Models 1 and 2 in 6 Viscous Time Scales

    图  6   模型3、4在6个粘性时间尺度内的外核极向磁能

    Figure  6.   Poloidal Magnetic Energy of the Outer Core Calculated by Models 3 and 4 in 6 Viscous Time Scales

    图  7   模型1、2在6个时间尺度内的外核环向磁能

    Figure  7.   Toroidal Magnetic Energy of the Outer Core Calculated by Models 1 and 2 in 6 Viscous Time Scales

    图  8   模型3、4在6个时间尺度内的外核环向磁能

    Figure  8.   Toroidal Magnetic Energy of the Outer Core Calculated by Models 3 and 4 in 6 Viscous Time Scales

    图  9   6个粘性时间尺度内模型1、2在核-幔边界处的磁场强度

    Figure  9.   Magnetic Field Intensity at Core-Mantle Boundary of Models 1 and 2 in 6 Viscous Time Scales

    图  10   6个粘性时间尺度内模型3、4在核-幔边界处的磁场强度

    Figure  10.   Magnetic Field Intensity at Core-Mantle Boundary of Models 3 and 4 in 6 Viscous Time Scales

    图  11   6个粘性时间尺度内模型1、2在核-幔边界处的偶极子分量占比

    Figure  11.   Dipolarity at Core-Mantle Boundary of Models 1 and 2 in 6 Viscous Time Scales

    图  12   6个粘性时间尺度内模型3、4在核-幔边界处的偶极子分量占比

    Figure  12.   Dipolarity at Core-Mantle Boundary of Models 3 and 4 in 6 Viscous Time Scales

    图  13   模型1、2在6个粘性时间尺度内的磁雷诺数

    Figure  13.   Magnetic Reynolds Number of Models 1 and 2 in 6 Viscous Time Scales

    图  14   模型3、4在6个粘性时间尺度内的磁雷诺数

    Figure  14.   Magnetic Reynolds Number of Models 3 and 4 in 6 Viscous Time Scales

    表  1   模型1~4在6个粘性时间尺度的西向漂移圈数

    Table  1   Circles of West Drifts of 4 Models in 6 Viscous Time Scales

    模型 西向漂移圈数
    1 32±3
    2 49±3
    3 35±3
    4 44±3
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  • [1]

    Baron G C. A Discourse on the Revolutions of the Surface of the Globe, and the Changes Thereby Produced in the Animal Kingdom[M]. Philadelphia: Lea&Blanchard, 1831

    [2]

    Glatzmaier G A, Roberts P H. A Three-Dimensional Self-Consistent Computer Simulation of a Geomagnetic Field Reversal[J]. Nature, 1995, 377(6546): 203-209 doi: 10.1038/377203a0

    [3]

    Christensen U R, Aubert J, Hulot G. Conditions for Earth-Like Geodynamo Models[J]. Earth and Planetary Science Letters, 2010, 296(3): 486-496

    [4]

    Kageyama A, Sato T. Computer Simulation of a Magnetohydrodynamic DynamoⅡ[J]. Physics of Plasmas, 1995, 2(5): 1421-1431 doi: 10.1063/1.871485

    [5]

    Kuang W, Bloxham J. An Earth-Like Numerical Dynamo Model[J]. Nature, 1997, 389: 371-374 doi: 10.1038/38712

    [6]

    Stefani F, Albrecht T, Gerbeth G, et al. Towards a Precession Driven Dynamo Experiment[J]. Magnetohydrodynamics, 2014, 51(2): 275-283

    [7] 邓洪涛. 地球内核与磁场[J]. 武汉大学学报·信息科学版, 2010, 35(7): 854-856 http://ch.whu.edu.cn/article/id/989

    Deng Hongtao. The Inner Core and Geomagnetic Field[J]. Geomatics and Information Science of Wuhan University, 2010, 35(7): 854-856 http://ch.whu.edu.cn/article/id/989

    [8]

    Glatzmaier G A. Introduction to Modelling Convection in Planets and Stars[M]. Princeton: Princeton University Press, 2013

    [9]

    Christensen U R, Aubert J, Cardin P, et al. A Numerical Dynamo Benchmark[J]. Physics of the Earth and Planetary Interiors, 2001, 128(1): 24-34

    [10]

    Thomas G, Johannes W, Ankit B, et al. Welcome—Magic 5.6 Documentation[EB/OL]. [2019-3-29]. https://magic-sph.github.io/

    [11]

    Lauren W, Jessica I. Reconciling the Hemispherical Structure of Earth's Inner Core with Its Super-Rotation[J]. Nature Geoscience, 2011, 4(4): 264-267 doi: 10.1038/ngeo1083

    [12]

    Wicht J. Inner-Core Conductivity in Numerical Dynamo Simulations[J]. Physics of the Earth and Planetary Interiors, 2002, 132(4): 281-302 doi: 10.1016/S0031-9201(02)00078-X

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出版历程
  • 收稿日期:  2020-07-23
  • 发布日期:  2022-04-04

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