Periodic variability of surface ozone concentration over western and central Europe from observational data

Abstract

Characteristics of periodic variability of surface ozone concentration at 98 western and central European stations participating in the EMEP program for at least 7 (up to 14) years are determined. Daily and hourly model concentrations of surface ozone for each station are given in an analytical form that presents a sum of a constant constituent and basic harmonics that determine ozone concentration variability throughout a year and a day. A 12-month harmonic, whose maximum is observed in the spring period (in Northern Europe it is observed 1 to 2 months earlier than in Southern Europe) dominates in the energy spectrum of seasonal variability of daily mean ozone concentration at most stations. The energy part of higher (6-and 4-month) harmonics is the largest at the stations close to the sea and ocean coasts. Higher harmonics largely influence the time of the ozone extremum formation, shifting it towards the summer, or even forming a second (summer) maximum, whose magnitude at a number of stations (in Italy, Hungary, in the south of Germany, and in some others) exceeds the spring maximum. A 24-hour harmonic dominates in the energy spectrum of daily ozone variability. The maps of a "normal" distribution of surface ozone fields and their standard deviations for different seasons and time of the day have been compiled based on the model characteristics. The "norms" derived can be used to detect anomalies in the temporal trend of the surface ozone and to validate its climate changes.

Surface Ozone Variability and Trend over Urban and Suburban Sites in Portugal

“…Further, Ferreira et al (2004) observed that high numbers of exceedances of the information threshold (180 µg m -3 -one hour) are usually registered in July and August period. This confirms that the observed bimodal variation in the seasonal cycle of surface O 3 with thespring maxima around April-May is mainly due to the dynamics of atmospheric processes in the atmospheric boundary layer and the summer maxima in July-August is due to the photochemical ozone generation (Tarasova et al, 2007;Zvyagintsev et al, 2008). Further, the spring relative maxima and the summer absolute maxima observed in the 8 hr monthly mean and in the daily maximum surface O 3 time series is representative of day time photochemistry due to high solar radiation and temperature leading to high numbers of exceedances during the summer, whereas the spring absolute maxima and summer relative maxima observed in the monthly mean surface O 3 time series is representative of the 24 hour average with longer nighttime period during spring compared to the summer time.…”

Economic impacts of ambient ozone pollution on wood production in Italy

“…The spatial distribution of POD1 along the Italian peninsula showed lower values in the Alpine forests in the North (on average 12 mmol m −2 ) and higher values in the typical Mediterranean climate of the South (on average 23 mmol m −2 ) and the islands (~ 41 mmol m −2 ). These values and the North-to-South increase are similar to what observed for the entire Europe 26 , as the warmer climate in the South stimulates O 3 formation 27 . These POD1 values are well above the critical levels of 4 and 8 mmol m −2 identified by 28 for the protection of deciduous broadleaves (birch and beech) and conifers (Norway spruce), respectively, stressing that most of Italian forests are exposed to severe O 3 risks.…”

Surface ozone concentration variability in Moscow and Kiev

“…The diurnal nighttime SOC "pseudomaximum" is observed on rather small territory around big cities (the typical size is several tens of kilometers). Episodes with increased SOC values in the warm period are observed on the territories with the typical size of several hundreds of kilometers [8,10] that indicates the influence of general regional level of ozone's predecessors on the SOC.…”

“…In Russia and the Ukraine, such norm is the single (averaged for 20 minutes) ozone concentration being equal to 160 mg/m 3 (corresponds to approximately 80 ppb [17]) [3]. In Western Europe, 180 mg/m 3 is considered to be the critical ozone concentration [15] at which, according to the legislation, the authorities must inform the population that corresponds approximately to the level of Russian MPV since the background SOC there are 20 mg/m 3 higher than in Moscow region [8]. The World Health Organization recommends to Europe to consider the concentration of 100 mg/m 3 averaged for eight hours as the safe ozone level [14].…”