D E S C R I P T I O N O F W O R K - MEGAPOLI - Dmi

MEGAPOLI 212520
Paris and London are the only two cities within the European Union that strictly correspond to the
definition of a megacity (i.e. population larger than 5 million people). The Rhine-Ruhr and Po
Valley areas have megacity features even if they can be better described as urban conglomerations
than as a single metropolitan area (Figure 5). The estimated loss of life expectancy due to air
pollution is quite high in these areas (Figure 6) and therefore, attaining the air pollutant
concentration limits, imposed by the EC air quality framework, and daughter directives is presently
critical for different air pollutants, e.g. PM and NO2.
2 nd Level
3 rd Level
1 st Level
Paris,
London,
Rhine-Ruhr,
Po Valley
Moscow, Istanbul, Mexico City,
Beijing, Shanghai, Santiago, Delhi,
Mumbai, Bangkok, New York,
Cairo, St.Petersburg, Tokyo
All megacities:
cities with a population > 5 Million
Figure 4: The pyramid of megacities in focus in MEGAPOLI.
Paris, with the belt of surrounding suburbs, is the largest metropolitan area in Europe, with a
population around 11 million people. The very dense urbanised area is concentrated on a limited
surface, a quasi circle with about 20 km diameter, surrounded by rural areas. The city and
surroundings are located in flat terrain; regional atmospheric circulation is thus mainly driven by
synoptic scale weather patterns. Due to strong and concentrated emissions, several air quality
standards are exceeded within the urban agglomeration, especially annual average NO2 and PM10
concentrations. Ozone concentrations reach often very high values in the Paris plume. However,
detailed aerosol measurements (chemistry and size distribution) and quantitative knowledge on
particulate matter sources in the area is lacking and little information exists about the Paris plume.
Moreover, air pollution episodes have been recently very probably accentuated by climate change,
as for example during the summer 2003 heat wave. These different reasons led us to the choice to
carry out the MEGAPOLI field measurements in and around Paris (WP3). Indeed, the relative
isolation of Paris from other major urban areas makes it a suitable location for the investigation of
the regional effects of megacities and the physical and chemical evolution of the corresponding
pollutants, both in the urban area and in the plume (WP4 and WP5).
The Rhine-Ruhr and Po Valley basins suffer air quality conditions worse than those experienced by
Paris and London. This is mainly due to high urban and industrial emissions and to the adverse
meteorological conditions that often affect the two regions. The Po River Basin includes six
administrative regions, and has a total population of about 16 million people. The Basin accounts
13
• Urban (and Regional and Global
and some Street) Scale Modelling
• Available and New Observations
• Tool Application and Evaluation
• Mitigation
• Regional (and Global and
some Urban) Modelling
• Available Observations
• Implementation of
Integrated Tools
• Global Modelling
• Satellite studies