Abstract

We have produced a 5-year mean secular variation (SV) of the geomagnetic field for the period 2020–2025. We use the NASA Geomagnetic Ensemble Modeling System (GEMS), which consists of the NASA Goddard geodynamo model and ensemble Kalman filter (EnKF) with 400 ensemble members. Geomagnetic field models are used as observations for the assimilation, including gufm1 (1590–1960), CM4 (1961–2000) and CM6 (2001–2019). The forecast involves a bias correction scheme that assumes that the model bias changes on timescales much longer than the forecast period, so that they can be removed by successive forecast series. The algorithm was validated on the time period 2010-2015 by comparing with CM6 before being applied to the 2020–2025 time period. This forecast has been submitted as a candidate predictive model of IGRF-13 for the period 2020–2025.

Graphical abstract

中文翻译：

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使用 NASA GEMS 集合卡尔曼滤波器的地磁长期变化预测：IGRF-13 的候选 SV 模型

摘要

我们制作了 2020-2025 年地磁场的 5 年平均长期变化 (SV)。我们使用 NASA 地磁集合建模系统 (GEMS)，它由 NASA 戈达德地球发电机模型和具有 400 个集合成员的集合卡尔曼滤波器 (EnKF) 组成。地磁场模型被用作同化的观测，包括gufm1（1590–1960）、CM4（1961–2000）和 CM6（2001–2019）。预测涉及偏差校正方案，该方案假设模型偏差在时间尺度上的变化比预测周期长得多，因此它们可以通过连续的预测序列来消除。该算法在 2010-2015 年期间通过与 CM6 进行比较验证，然后再应用于 2020-2025 年期间。该预测已作为 2020-2025 年期间 IGRF-13 的候选预测模型提交。

图形概要