Figure 5.
Changes of the diurnal variations of O3 mixing ratios between 1994–2003 and 2004–2012.
Diurnal profiles of mean tropospheric O3 mixing ratios are given for 1994–2003 (left panel) and 2004–2012 (middle panel). The relative differences of mixing ratio between the two periods are shown in the right panel. Crosses indicate the pressure levels and time interval at which the differences are statistically significant regarding the SWS t-test (see text in Sect. 3.1 for details on this test). The mean O3 mixing ratios in 2004–2012 appear stronger than in 1994–2003 at most pressure levels and during most of the day, although all the differences are not significant regarding the SWS t-test. The largest increases (above +15%) are observed in the first levels during the night.
