Extreme variations in the direction of Earth’s magnetic field contain important information regarding the operation of the geodynamo. Paleomagnetic studies have reported rapid directional changes reaching 1° yr⁻¹, although the observations are controversial and their relation to physical processes in Earth’s core unknown. Here we show excellent agreement between amplitudes and latitude ranges of extreme directional changes in a suite of geodynamo simulations and a recent observational field model spanning the past 100 kyrs. Remarkably, maximum rates of directional change reach ~10° yr⁻¹, typically during times of decreasing field strength, almost 100 times faster than current changes. Detailed analysis of the simulations and a simple analogue model indicate that extreme directional changes are associated with movement of reversed flux across the core surface. Our results demonstrate that such rapid variations are compatible with the physics of the dynamo process and suggest that future searches for rapid directional changes should focus on low latitudes.

地球磁场方向的极端变化包含有关大地发电机运行的重要信息。古磁研究已经报告了迅速的方向变化，达到1°yr ^-1，尽管这些观察结果是有争议的，并且与地球核心的物理过程之间的关系还不清楚。在这里，我们在一套地球动力学模拟和最近跨越100 kyrs的观测场模型中显示了极端方向变化的幅度和纬度范围之间的极佳一致性。显着地，最大方向变化率达到〜10°yr ^-1，通常在场强降低的时候，几乎比电流变化快100倍。对模拟的详细分析和简单的模拟模型表明，极端的方向变化与反向磁通在铁心表面的运动有关。我们的结果表明，这种快速变化与发电机过程的物理过程兼容，并表明未来对快速方向变化的搜索应集中在低纬度上。