Variations of mean zonal winds relating to the ozone hole

Abstract

Dynamical effects on the development of the Antarctic ozone hole have been investigated through the analysis of the interannual variations of the monthly mean zonal winds in the southern hemisphere (SH) stratosphere using the National Meteorological Center (NMC) analyzed geopotential height data, below and above 50 mbar, and the United Kingdom Meteorological Observatory (UKMO) analyzed temperature data, from which geopotential heights are calculated. It is found that the year‐to‐year changes of the mean zonal winds in the SH winter and spring (August, September, and October) in the lower stratosphere have shown no clear trends during the period from 1980 to 1988, in contrast to the ozone depletion and temperature decline. However, surprisingly, there are apparent differences in the zonal wind comparison between the 1980s and the early 1970s which are cited from the new CIRA model compiled by Barnett and Corney (1985). The differences in the Antarctic lower stratosphere in the winter and spring are evident in that the zonal winds poleward (equatorward) of 60°S become weaker (stronger) in the 1980s by over 10 m/s than in the early 1970s. On the other hand, the amplitudes of stationary waves of wavenumber 1 in the 1980s become weaker by about half of the amplitudes in the early 1970s. These results indicate that the dynamical condition appropriate for the development of the ozone hole, less poleward transport of heat and ozone by planetary waves, had been already present during the appearance of the ozone hole in about 1980 and has still continued.