This paper presents the longitudinal
distribution of total ozone along several latitudinal circles from both hemispheres
during a strong geomagnetic storm that occurred on 24 August 2005 after a solar
proton event (the maximum flux of protons with energy > 10 MeV was 1.70 × 107 protons cm-2.day-1.sr-1 on 23 August). For
that, we use average daily values of total ozone observations (=column ozone
amount) in Dobson units for the period 18-25 August 2005 (obtained from the Total Ozone Mapping Spectrometer, TOMS).
The considered storm occurred after a relatively quiet geomagnetic period and
it is not superposed by another perturbation, which permit us to identify
clearly the effects of the geomagnetic storm on total ozone. The results show statistically significant decreases in ozone along the latitudinal
circles 70°N and 70°S (summer and winter), no
statistically significant effects at middle latitudes (40°S) and sparse statistically
significant increases at low latitudes (20°S). The role of some mechanisms to
explain the features observed is considered.