Geomagnetic variations during periods of terrestrial magnetic field polarity reversals

在地磁场反转期间，磁场强度下降到当前磁场强度的约1/10。这就提出了一个问题，即磁场强度的这种剧烈变化可能对磁层动力学引起的地球电离层中的电流系统产生何种影响。电离层电流是地球磁场外部的主要贡献者。目前，这种外部贡献在极纬可能达到2000 nT。然而，平均而言，外部贡献约为发电机起源的内部磁场贡献的1/100。因此，与内部部分相比，外部部分通常非常小。例如，在高纬度地区，电离层电流的地面磁效应主要是由于电离层霍尔电流的磁效应。在极性反转期间，电离层霍尔电导率可以显著增加，导致外部磁场变化的水平增加。初步估计表明，外部磁场变化与内部磁场变化的比值可能达到1阶。拟议研究的目的是详细分析地磁场极性反转期间的地磁变化问题。

During periods of terrestrial magnetic field reversals the field intensity drops to about 1/10 of the current magnetic field strength. This raises the question which effects such a drastic change of the field magnitude may have on the current systems in the Earth ionosphere caused by magnetospheric dynamics. Ionospheric currents are the major contribution to the external part of the Earth magnetic field. At the present time such external contributions may reach up to 2000 nT at polar latitudes. However, on the average the external contribution amounts to about 1/100 of the internal magnetic field contribution of dynamo origin. Thus, the external part is usually very small compared to the internal part. At high latitudes, for example, the ground magnetic effect of the ionospheric currents is mainly due to the magnetic effect of the ionospheric Hall currents. During a polarity reversal the ionospheric Hall conductivity can significantly increase leading to an increased level of external magnetic field variations. First estimates indicate that the ratio external to internal magnetic field variations may well reach values of the order 1. It is the aim of the proposed study to analyze in detail the question of geomagnetic variations during polarity reversals of the geomagnetic field.