Basic Statistical Properties of the 10-years Ozone Daily Time Series from Stara Zagora

In order to examine some important statistical parameters, the ozone series were detrended and seasonally adjusted.Then we determined the central moments as well as the skewness and kurtosis of the series.The distributions were analysed using histograms and Q-Q plots for different seasons.We divided the series into two groups with high and low ozone variations.The group with high variations includes the months from December to March (DJFM), while the group with lower variations includes the months from May to October (MJJAASO) with standard deviations of 36 DU and 19 DU, respectively.The reason for the high ozone variations is the frequent exchange of ozone-rich polar air masses with pure ozone air masses from the mid-latitudes and the tropics.The Q-Q plots show that the distributions for the two groups are close to normal distribution.On short time scales of a few days, the ozone residuals can be described by an AR (1) model.Long-term persistence was investigated using detrended fluctuation analysis (DFA).On scales ranging from a few days to a crossover of about 20 days, a Hurst coefficient of 0.93 was found, which characterises the series on these scales by strong persistence, far from chaotic behaviour but close to 1/f noise.From the crossover onwards, a Hurst coefficient of around 0.7 characterises the long-range correlation.The crossover achieved in the DFA of the seasonally adjusted and detrended total column ozone (TCO) indicates a change in the dominant processes on different time scales.