Effects of solar UV irradiation on dynamics of ozone hole in Antarctica

Abstract

To study relationship between changes in solar ultraviolet (UV) irradiance and dynamics of the Antarctic ozone hole during the final breakup of the Antarctic polar vortex the composite Mg II index has been used as a proxy for the solar UV irradiance. The short-term changes in the UV-irradiation have been separated after removing the long- and middle term variations. Examination of maps of the total ozone distribution above Antarctica showed that the ozone hole collapse succeeds displacement of the hole center from the South Pole, where the absolute minimum of total ozone is usually located. Comparison with variations of the UV irradiation reveals that phase of the quick decay of the ozone hole is preceded by the maximal solar UV irradiation in course of the regular 27-days variation. Analysis of the vertical profiles of ozone density, temperature, wind speed and total column ozone above station Amundsen–Scott showed that ozone hole is filled up in spring typically in two phases. During the first gradual phase the ozone filling occurs very slowly, whereas the second phase is characterized by sudden and sharp increase of the ozone content (about 50–100 Dobson units in few days). In this period the strong wind disturbances are observed in the higher stratosphere as well. Conclusion is made that rate of the ozone hole filling during the Antarctic later spring depends on the intensity of solar UV, and high level of the UV irradiation turns out to be sufficient to initiate the dynamical processes leading to the collapse of the winter circumpolar vortex.