PARTHENO2N

Pollution of air in the extended region of Athens: Space-based Nitrogen Dioxide (NO2) observations and their comparison with remote and ground–based measurements and modeling simulations

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 Obiettivo del progetto (Objective)

'Nitrogen Dioxide (NO2) is one of the most important tropospheric pollutants leading to poor air quality and inducing climate changes. Public exposure to NO2 at urban environments is of great health concern as it is known to cause human respiratory problems. NO2 is one of the main precursors of the photochemical smog; it contributes to the acidification of the atmosphere, control the oxidation capacity of the atmosphere and affect locally its radiative forcing. In order to access the significance of these issues, a deep understanding of all relevant, physical and chemical processes, that control the atmosphere, is required. To this end, one of the most important steps towards filling the gap of knowledge on NOx relevant processes has been made recently, via space-based observations of the NO2 vertical column densities (VCD). “PARTHENO2N” focuses on the investigation of the abundances and the seasonal changes of the NO2 columns retrieved over the region of Athens and its surroundings from four different satellite instruments (GOME, SCIAMACHY, GOME-2 and OMI). In order to gain confidence in satellite observations, it is important to investigate, both qualitatively and quantitatively, their representativeness for different geo-locations. “PARTHENO2N” will provide, for the first time, a high quality intercomparison of the satellite data with various ground based, in situ and remote sensing, observations performed by: i) a novel multi axis differential optical absorption spectroscopy system (MaxDOAS) measuring both the vertical columns and profiles of NO2 ii) a Brewer-MK4 spectrometer used to retrieve column densities of NO2 and iii) in situ chemiluminescence analysers recording the nitrogen oxides mixing ratios. Lastly the validated satellite observations are going to be compared with the simulations of the well established chemical transport model (Oslo-CTM2) in order to improve our understanding concerning the effect of anthropogenic emissions in urban areas.'

Introduzione (Teaser)

The economic crisis in Greece has had an unexpected surprise on its capital. Athens is now registering much less pollution in its atmosphere.

Descrizione progetto (Article)

The vibrant, dynamic Greek capital may indeed be a popular tourist hub with attractions such as the Acropolis, but it has generally been a magnet for pollution due to its sheer size. Athens' geographical location in the Attica basin surrounded by mountains, including its proximity to the port city of Piraeus and nearby industrial area, has exacerbated this phenomenon. Among the more dangerous pollutants in the greater region's atmosphere is nitrogen oxide (NO2) produced from industry and transport emissions, endangering the health of its four million inhabitants.

Specifically, NO2 is known to cause respiratory problems and is behind several EU laws that try to limit pollution. With this in mind, the EU-funded project PARTHENO2N (Pollution of air in the extended region of Athens) assessed the seriousness of the threat. It studied NO2 levels in the city's atmosphere and built computer models in order to assess the impact of the pollutant.

To achieve its aims, the project looked at satellite observations of NO2 levels from 2003 to 2012 over Greece and specifically Athens. It then examined NO2 levels as registered by ground-based equipment from 2000 to 2012 to simulate NO2 concentrations as accurately as possible.

Interestingly, the results from both sources showed more than a 30 % drop in NO2 levels measured by the reduction in vertical NO2 columns. This was attributed directly to the economic crisis as many inhabitants migrated to rural areas, businesses closed down and the high fuel prices discouraged private transport.

In all, PARTHENO2N demonstrated a novel approach to corroborating ground and satellite data on pollution levels, giving policymakers better information on managing pollution. The results could help Athens seize this golden opportunity to keep pollution levels down by creating a more sustainable city post-crisis.