Latitude dependency of the geomagnetic secular variation S parameter: A mathematical artifact
Latitude dependency of the geomagnetic secular variation S parameter: A mathematical artifact
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DOI：
10.1029/2011gl050330
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发表时间：
2012-01
影响因子：
5.2
通讯作者：
J. Linder;S. Gilder
中科院分区：
文献类型：
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作者：
J. Linder;S. Gilder
长期变化，即地球磁场随时间的变化，反映了地球发电机的能量状态。长期变化通常被古地磁学家量化为虚拟地磁极到其平均极的角距离的标准偏差，称为S值。长期以来，该参数被认为表现出纬度依赖性[S（λ）]，其起源被广泛归因于时变偶极和非偶极分量的组合。S（λ）的斜率和大小是了解地磁场及其演化的基础。在这里，我们表明，S（λ）源于从方向到极点的转换的数学偏差，因此定向种群更好地量化了古长期变化的局部估计。
Secular variation, the change in the Earth's magnetic field through time, reflects the energy state of the geodynamo. Secular variation is commonly quantified by paleomagnetists as the standard deviation of the angular distances of the virtual geomagnetic poles to their mean pole, known as the S value. This parameter has long been thought to exhibit latitude dependence [S(λ)], whose origin is widely attributed to a combination of time‐varying dipole and non‐dipole components. The slope and magnitude ofS(λ) are taken as a basis to understand the geomagnetic field and its evolution. Here we show that S(λ) stems from a mathematical aberration of the conversion from directions to poles, hence directional populations better quantify local estimates of paleosecular variation.