Eija I. Tanskanen,
Aalto University, Finland
Title: The Sun-Earth magnetic coupling for last 100 years
Biography
Biography: Eija I. Tanskanen,
Abstract
The Sun and Earth are magnetically coupled and changes in the solar activity modulate geomagnetic activity at high and low latitudes of the Earth. We examine decadal and seasonal variability of auroral substorms and their source regions at the Sun. We have identified auroral substorms from the high-latitude magnetic recordings and geomagnetic storms from the magnetometers close to the magnetic equator. We found out that the largest substorms can occur at any season depending on the state of the Sun, and that the activity is strongly modulated by the Alfvén waves occurring during the all solar cycle phases, but in particular during the declining solar cycle phase. When studing the stormy hours at the equator, we found out that by far the largest amount of stormy hours were seen in 1989, 1991 and 1960 while the least stormy hours are seen in 1964 and between 2007-2009. The classical seasonal pattern seems to be as rare in high and low-latitudes of the Earth, similarly to both hemispheres.