On the temporal and spatial variation of ozone in Cyprus

• More than sixteen years of ozone observations at a rural station in Cyprus (Agia Marina) were statistically analyzed.
• The observations revealed the presence of a prominent seasonality with the maxima observed during summer.
• A non-significant (a < 0.05) upward trend over the 16 years equal to 0.11±0.12 ppbv y-1 has been computed.
• Concurrent observations at three remote sites suggest that high ozone levels are mostly linked to long-range-transport.
• The local photochemistry/deposition can account for up to ~3 ppbv i.e 6% of the observed ozone levels.

More than sixteen years (1997–2013) of continuous ozone concentrations at the rural Agia Marina (EMEP, 532 m a.s.l.) station in Cyprus, together with a number of ancillary chemical and meteorological parameters have been analyzed on a multiannual, annual and diurnal basis. The observations reveal a) the presence of a prominent seasonality with maxima observed during summer (54 ± 5 ppbv) and the minima in winter (39 ± 3 ppbv) b) a relatively small diurnal variability with the noon levels (50 ± 9 ppbv) being higher by ~ 4 pbbv compared to nighttime (46 ± 9 ppbv) and c) a non-significant upward trend over the 16 years of 0.11 ± 0.12 ppbv y− 1. To assess the spatial variability over Cyprus, simultaneous measurements in 2011–2012 have been performed at Inia, Stavrovouni and Cavo Greco, three remote marine monitoring sites located to the west, central and the east of the Island, respectively. Our results show that ambient ozone levels over Cyprus are mostly influenced by regional/transported ozone while the local precursor emissions play a minor role in ozone formation. On an annual basis a net ozone reduction of 1.5 and 1.0 ppbv occurs when the air masses originate from northerly and westerly directions, respectively, while this is 2.4 ppbv during southerly wind. This suggests continuous net ozone loss controlled by surface deposition and photochemical destruction, and highlights the importance of long-range transport in controlling ozone levels in Cyprus.

The left panel shows the location of Cyprus in the East Mediterranean region and the major wind sectors, including their relative annual frequency during the period 1997–2012. A fraction of 11% (not shown here) is attributed to air masses of local/mixed origin. The right panel depicts the daily (in black) and monthly (in red) means of ozone concentrations observed at the rural Agia Marina station for the period 1997–2012. Our work clearly highlights that high ozone levels over Cyprus are directly linked to long-range-transport and that local photochemistry/deposition can account for up to about 3 ppbv i.e 6% of the observed ozone levels.Figure optionsDownload as PowerPoint slide