Stratospheric ozone response to short- and intermediate-term variations of solar UV flux

On the basis of three years (October 1991 through September 1994) of UARS SOLSTICE (solar stellar irradiance comparison experiments) and MLS (microwave limb sounder) data, correlations between tropical ozone and spectral solar UV flux have been studied. In addition to the 27-day period of solar rotation, this new result shows a relatively weak UV-ozone correlation at periods of 60-80 days in the upper stratosphere. The 60-80 day correlation coefficient (similar to 0.5) is somewhat smaller than the 27-day correlation (similar to 0.7). For the 60-80 day periodicity the overall phase lag of ozone is about 2 weeks throughout the 1-10 mbar layer, but the phase relation differs each year. This suggests that dynamical effects could be influencing the 60-80 day ozone variation. Although the 60-80 day solar variation is much smaller than the 27-day variation, the ozone response to these solar variations is about as strong. Further investigation of the 60-80 day variation using alternate data sets for different time periods would be desirable.