CHAOS-2-a geomagnetic field model derived from one decade of continuous satellite data
CHAOS-2-a geomagnetic field model derived from one decade of continuous satellite data
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DOI：
10.1111/j.1365-246x.2009.04386.x
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发表时间：
2009-12-01
影响因子：
2.8
通讯作者：
Toffner-Clausen, Lars
中科院分区：
文献类型：
--
作者：
Olsen, Nils;Mandea, Mioara;Toffner-Clausen, Lars
我们利用Orsted、CHAMP和SAC-C三颗卫星10多年来的高精度地磁测量数据导出了近地磁场模型。该模型是对之前两个模型CHAOS（Olsen et al. 2006）和xCHAOS（Olsen & Mandea 2008）的更新。数据选择和模型参数化密切遵循那些选择用于推导这些模型。主要区别在于静态场的最大球谐度（n = 60，与CHAOS和xCHAOS的n = 50相比），以及核心场时间变化，其中球谐展开系数高达n = 20，由5阶样条描述（节距为6个月）。与前几个模式相比，对CHAOS-2模式的时间正则化进行了改进。事实上，二阶和高阶时间导数的核心领域的阻尼最小化的平方磁场强度的二阶时间导数在核幔边界。CHAOS-2模型描述了由地面地磁观测站监测的快速时间变化，比其前身要好得多。
We have derived a model of the near-Earth's magnetic field using more than 10 yr of high-precision geomagnetic measurements from the three satellites Orsted, CHAMP and SAC-C. This model is an update of the two previous models, CHAOS (Olsen et al. 2006) and xCHAOS (Olsen & Mandea 2008). Data selection and model parameterization follow closely those chosen for deriving these models. The main difference concerns the maximum spherical harmonic degree of the static field (n = 60 compared to n = 50 for CHAOS and xCHAOS), and of the core field time changes, for which spherical harmonic expansion coefficients up to n = 20 are described by order 5 splines (with 6-month knot spacing) spanning the years from 1997.0 to 2009.5.Compared to its predecessors, the temporal regularization of the CHAOS-2 model is also modified. Indeed, second and higher order time derivatives of the core field are damped by minimizing the second time derivative of the squared magnetic field intensity at the core-mantle boundary. The CHAOS-2 model describes rapid time changes, as monitored by the ground magnetic observatories, much better than its predecessors.