Abstract :
The wintertime distribution of total ozone over middle latitudes of the Northern Hemisphere is strongly longitudinally asymmetric, which is not the case in summer with much weaker longitudinal asymmetry. As a consequence of that, the effect of geomagnetic storms on total ozone can be observed only in winter, when it looks like re-distribution of ozone resulting in substantial diminishing of longitudinal asymmetry. The storm effect is substantial under specific conditions in some regions but not globally, and it does not appear as a detectable effect in zonal mean values of total ozone, as it is shown for latitude 50°N. The effects of Forbush decreases of the cosmic ray flux on total ozone provide a similar pattern. Both effects seem to be related to changes in atmospheric dynamics, thus being rather indirect. The geomagnetic storm effects in the surface pressure field provide a similar spatial pattern, as well. The strong non-zonality of effects of geomagnetic storms and Forbush decreases on total ozone and absence of such effects in zonal mean values stresses the necessity to avoid the zonal mean values in studies of impacts of extraterrestrial processes and phenomena on total ozone and the middle atmosphere.
