Long-Term Variation of the Geoelectric Activity Index T

摘要

We study the long-time behavior and variability of the Earth geomagnetic activity based on the uniquely long geoelectric field observations recorded at the Nagycenk Geophysical Observatory for the past five decades. According to our results there is no clear correlation between the solar activity (expressed in sun-spot number) and the daily T index. On the other hand, we found an almost linear relation between the Ap and T indices.