![Hier klicken, um den Treffer aus der Auswahl zu entfernen](images/unchecked.gif) |
Titel |
Investigation of characteristics and transformation processes of megacity emission plumes using a mobile laboratory in the Paris metropolitan area |
VerfasserIn |
S.-L. von der Weiden-Reinmüller, F. Drewnick, Q. Zhang, F. Meleux, M. Beekmann, S. Borrmann |
Konferenz |
EGU General Assembly 2012
|
Medientyp |
Artikel
|
Sprache |
Englisch
|
Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 14 (2012) |
Datensatznummer |
250063222
|
|
|
|
Zusammenfassung |
A growing fraction of the world’s population is living in urban agglomerations of
increasing size. Currently, 20 cities worldwide qualify as so-called megacities,
having more than 10 million inhabitants. These intense pollution hot-spots cause a
number of scientific questions concerning their influence on local and regional air
quality, which is connected with human health, flora and fauna. In the framework
of the European Union FP7 MEGAPOLI project (Megacities: Emissions, urban,
regional and Global Atmospheric POLlution and climate effects, and Integrated
tools for assessment and mitigation) two major field campaigns were carried out
in the greater Paris region in July 2009 and January/February 2010. This work
presents results from mobile particulate and gas phase measurements with focus on
the characteristics of the Paris emission plume and its impact on the regional air
quality and on aerosol transformation processes within this plume as it travels away
from its source. In addition differences between summer and winter conditions are
discussed.
The mobile laboratory was equipped with high time resolution instrumentation to
measure particle number concentrations (dP > 2.5 nm), size distributions (dP ~ 5 nm –
32 μm), sub-micron chemical composition (non-refractory species using Aerodyne
HR-ToF-AMS, PAH and black carbon) as well as major trace gases (CO2, SO2, O3, NOx)
and standard meteorological parameters. On-board webcam and GPS allow detailed
monitoring of traffic situation and vehicle track. In a total of 29 mobile and 25 stationary
measurements with the mobile laboratory the Paris emission plume as well as the
atmospheric background was characterized under various meteorological conditions. This
allows investigating the influence of external factors like temperature, solar radiation or
precipitation on the plume characteristics.
Three measurement strategies were applied to investigate the emission plume. First,
circular mobile measurements around Paris provide cross sections through plume air masses
as well as local background variation measurements. Second, radial measurement
trips beginning near the outer area of the agglomeration extending up to ~200 km
distance from Paris along the direction of the emission plume provide insight into the
extension of the plume and transformation processes. Third, stationary measurements at
different locations provide background as well as pollution measurements, especially if
the wind direction is shifting, causing the plume to pass over the measurement
site.
During radial measurement trips the decrease in the concentrations of primary pollution
marker species as hydrocarbon-like organic aerosol, black carbon, PAH and NOx with
increasing distance from Paris is clearly observed. This decrease is mainly caused by dilution
processes, but additional aging effects are also detectable. While entering the emission plume
on cross section measurements a significant increase in such marker species compared to
background values can be seen. On the other hand, overall statistics of both campaigns shows
that day-to-day background variations influenced mainly by long range transported pollution
(i.e. air mass origin) are stronger than variations between background and plume on specific
days.
A description of the methods developed for analysing the mobile data will complete this
presentation. |
|
|
|
|
|