Geomagnetic storms, Forbush decreases of cosmic rays and total ozone at northern higher middle latitudes

Abstract

Space weather affects the Earth's atmosphere in many ways and through various phenomena. Among them, geomagnetic storms and the variability of the galactic cosmic ray flux belong to the most important ones as for the lower atmosphere. Here, we summarize our previous results on the effects of strong geomagnetic storms and strong Forbush decreases of galactic cosmic rays on the total ozone at the northern higher middle latitudes, and complete them with investigations of effects of geomagnetic storms not accompanied by Forbush decreases. The effects of strong geomagnetic storms and Forbush decreases occur only in the winter part of the year, under the high solar activity and the E-phase of QBO (E-max) conditions. The effects of storms seem to be a redistribution of ozone as a consequence of storm-related changes of circulation. No event contradicts the idea that the Forbush decreases are responsible for effects of geomagnetic storms on the lower atmosphere (troposphere and lower stratosphere) including total ozone. However, under the E-max conditions in the winter part of the year, only several Forbush decreases without geomagnetic storms and only one geomagnetic storm without the Forbush decrease occurred over more than 20 years.