Impact of Forbush Decreases and Geomagnetic Storms on the Atmospheric Ozone Profiles

Abstract

AbstractThe sensitivity of atmospheric ozone to geomagnetic storms and reduced cosmic rays' (CRs) intensity (called Forbush decrease [FD]) has been noticed for many years. However, it is still unclear what the factors affecting ozone density are—whether these are the complex changes induced by geomagnetic storms in the upper atmosphere and ionosphere, or it is the severe reduction of CRs accessing Earth's lower atmosphere. Analyzing two strong geomagnetic storms, accompanied by FDs, and another FD occurred in geomagnetically quiet conditions, we conclude that observed ozone changes support the idea about the existence of an additional source of ozone in the lower stratosphere. The ion‐molecular reactions of catalytic ozone production are initiated by secondary ionization, produced by cosmic radiation at these levels. This conclusion is supported by the fact that the strongest ozone depletion beneath its maximum is found in regions with the severest reduction of CR flux. Moreover, the time delay of ozone response (∼2 days), is short enough to be attributed to changes in circulation. In addition, we have examined the changes in the sea level pressure during the analyzed events and found out that the surface pressure follows dynamically the spatial pattern of the ozone changes, forced by the reduced amount of precipitating energetic particles in the atmosphere.