Abstract:

    A principal component analysis (PCA) is applied to the Southern Hemisphere (SH) total column ozone following the method established for analyzing the data in the Northern Hemisphere (NH) in a companion paper. The interannual variability (IAV) of extratropical O3 in the SH is characterized by four main modes, which account for 75% of the total variance. The first two leading modes are approximately zonally symmetric and relate to the Southern Hemisphere annular mode and the quasi-biennial oscillation. The third and fourth modes exhibit wavenumber-1 structures. Contrary to the Northern Hemisphere, the third and fourth modes are not related to stationary waves. Similar results are obtained for the 30-100-hPa geopotential thickness. The decreasing O3 trend in the SH is captured in the first mode. The largest trend is at the South Pole, with value ~-2 Dobson Units (DU)/yr. Both the spatial pattern and trends in the column ozone are captured by the Goddard Earth Observation System chemistryÂclimate model (GEOS-CCM) in the SH.

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