Total ozone‐solar activity relationship

Nearly 6 years of global ozone monthly mean data from the Nimbus 4 BUV instrument are compared with monthly values of solar activity using 10.7‐cm flux ( F (10.7)) as a parameter. Several techniques are explored in calculating the correlation between the two data sets, and all yield relatively high correlations, ranging from R = 0.68 for ‘raw’ monthly means to 0.94 using a 6‐month running mean for each data set. It is shown, however, that the bulk of the correlation is due to the long‐term decreasing trends in both data sets. When the long‐term trends are removed, a cross‐correlation analysis produces a maximum with no phase shift or with the ozone variations leading the solar variations by 1 month, thus reducing the likelihood of a cause and effect relationship on time scales of this order. Considering the current uncertainty in the long‐term stability of the BUV instrument, and the resulting uncertainty in any long‐term trend derived from its data, it is unrealistic to draw firm conclusions about a solar cycle influence on total ozone from this satellite data set.