Science. 1988 Jul 15;241(4863):328-30. doi: 10.1126/science.241.4863.328.
Magnetic field records at the earth's surface contain the effects of a variety of different source currents flowing in outer space. During the last decade, several computational techniques for the use of magnetometer data have been proposed to obtain the global pattern of the electric fields and currents and Joule heating in the ionosphere. The numerical algorithm has now been enormously improved, such that simultaneous more direct or in situ measurements by satellites and radars can be incorporated into the scheme. In particular, owing to recent progress in satellite-viewed auroral images, it is possible to estimate "instantaneous" patterns of the ionospheric electrodynamic quantities over the entire polar region with a time resolution of several minutes. This report demonstrates that, contrary to our conventional views, large ionospheric currents can flow in regions of low auroral activity.
地球表面的磁场记录包含了在太空中流动的各种不同源电流的影响。在过去的十年中，已经提出了几种用于磁强计数据的计算技术，以获得电离层中的电场、电流和焦耳加热的全球模式。数值算法现在已经得到了极大的改进，使得卫星和雷达的同时更直接或原位测量可以被纳入到这个方案中。特别是，由于最近在卫星观测极光图像方面的进展，有可能以几分钟的时间分辨率来估计整个极地区域的电离层电动力学量的“瞬时”模式。本报告表明，与我们的传统观点相反，在极光活动较弱的区域也可能有大的电离层电流流动。
