Analysis of Summer Ozone Observations at a High Mountain Site in Central Italy (Campo Imperatore, 2388 m a.s.l.)

Abstract

Abstract-Tropospheric ozone (O 3 ) is an important atmospheric pollutant and climate forcer. The Mediterranean basin is a hot-spot region in terms of short-term O 3 distribution, with frequent episodes of high tropospheric O 3 , especially during summer. To improve the characterisation of summer O 3 variability in the Mediterranean area, during the period 6-27 August 2009 an experimental campaign was conducted at Campo Imperatore, Mt Portella (CMP), a high mountain site (2,388 m a.s.l.) located in the central Italian Apennines. As deduced from analysis of atmospheric circulation, the measurement site was significantly affected by air masses originating over the Mediterranean basin, which affected the measurement site for 32 % of the time. Analysis of average values and diurnal and day-to-day variability revealed that CMP O 3 observations (average value 60.0 ± 5.1 ppbv) were comparable with measurements at other European mountain stations, indicating a prevalent effect of meteorological conditions and atmospheric transport on the synoptic scale. In fact, only a small ''reverse'' diurnal variation typically characterises diurnal O 3 variability because of local thermal wind circulation, which sporadically favours transport of air masses rich in O 3 from the foothill regions. Statistical analysis of five-day back-trajectory ensembles indicates that synoptic-scale air-mass transport from the Mediterranean Sea usually results in decreasing O 3 concentrations at CMP, whereas the highest hourly O 3 values are mostly associated with air masses from central continental Europe, eastern Europe, and northern Italy. High O 3 concentrations are also related to downward air-mass transport from higher altitudes. Comparison of in-situ O 3 variability with tropospheric O 3 satellite-based measurements reveals similar features of the two data sets. Together with the results from back-trajectory analysis, this indicates that CMP measurements might usefully improve characterisation of broad-scale O 3 variability over the central Mediterranean basin.

Observations of Thermally Driven Circulations in the Pyrenees: Comparison of Detection Methods and Impact on Atmospheric Composition Measured at a Mountaintop

“…At the high Alpine site Jungfraujoch (3450 m MSL) in Switzerland, for instance, recent studies with a variety of observations and methods (in situ radon and trace gas measurements; aerosol-layer detection by lidar; Lagrangian particle dispersion model) estimated that the station is under the influence of boundary layer emissions for 40%-60% of the year, with a significant impact on in situ aerosol measurements as compared with free-tropospheric conditions (Collaud-Coen et al 2011;Herrmann et al 2015;Poltera et al 2017). Cristofanelli et al (2013) analyzed summer ozone (O 3 ) observations at a mountain site (2388 m MSL) in the central Italian Apennines and found that the site was significantly affected by air masses from the Mediterranean basin for 32% of the time. Vertical exchange processes made complex by mountainous terrain (Rotach et al 2015;Steyn et al 2013) are less well understood than processes on flat terrain (Zardi and Whiteman 2013).…”

Temporal and Spatial Variation in, and Population Exposure to, Summertime Ground-Level Ozone in Beijing

“…Stratospheric ozone can protect the Earth’s surface from dangerous ultraviolet radiation from the sun, but ground-level ozone (O 3 ) is an important atmospheric pollutant and agent of climate change [ 1 ]. Ground-level ozone is mainly produced by a complex photochemical reaction between nitrogen oxides (NO X = NO + NO 2 ) and volatile organic compounds (VOCs) under strong solar radiation.…”

Weather regimes and related atmospheric composition at a Pyrenean observatory characterized by hierarchical clustering of a 5-year data set

“…In Cristofanelli et al (2013) differences of ozone concentrations are shown at Campo Imperatore, in the Abruzzi massif, depending on whether air masses come from the Mediterranean sea or from the European continent. Continental air masses tend to bring air masses with higher ozone values.…”

“…Another common way to analyse air composition data at mountain sites is to track (usually at a larger continental scale) the air masses using backward trajectories or dispersion models. The composition measurements are then sorted by geographical source regions (e.g., Cui et al (2011) and Loeoev et al (2008) at the Jungfraujoch; Cristofanelli et al (2013) at Campo Imperatore, central Italy; Perry et al (1999) at Mauna Loa, Hawaii; among many). The two studies at the Jungfraujoch highlight differences in ozone concentration and other chemical components such as CH 4 and CO (Loeoev et al, 2008), depending on whether air masses were influenced by the European planetary boundary limit or were long-range advected to Jungfraujoch.…”