On the basis of expanding random geophysical fields in terms of empirical orthogonal functions (EOFs), it is shown that winter monothly mean total ozone (TO) anomalies in the midlatitude northern hemisphere (TOMS, 1979-1992) are associated with a large-scale model of atmospheric variability-the Arctic Oscillation (SO). The second TO EOF has a spatial structure similar to the AO structure, which is determined by the first EOF of the sea-level pressure, and the coefficients of these EOFs are anticorrelated. An analysis of a longer TO series obtained from the data of ground-based stations (1958-1998) has shown that a similar anticorrelation occurs between the index of the North Atlantic oscillation (NAO), which is a regional part of the AO, and the TO anomalies averaged over December-march. A portion of a negative TO trend in the middle and high latitudes of the Northern hemisphere can be attributed to a decrease in wave activity in the lower stratosphere. this decrease is associated with AO and NAO intensification started in the late 1960s. AO and NAO decay after 1995 resulted in a TO increase in the midlatitude Northern Hemisphere. This increase was especially noticeable in 1998-1999.
展开▼
