 |
| Titel |
Total OH reactivity measurements aboard the Zeppelin NT during the PEGASOS campaign 2012: Contributions of substance classes to the total OH reactivity |
| VerfasserIn |
Robert Wegener, Julia Jäger, Andreas Hofzumahaus, Franz Rohrer, Birger Bohn, Theo Brauers, Sebastian Broch, Sebastian Gomm, Rolf Häseler, Frank Holland, Jennifer B. Kaiser, Frank Keutsch, Xin Li, Insa Lohse, Keding Lu, Ralf Tillmann, Glenn M. Wolfe, Thomas F. Mentel, Astrid Kiendler-Scharr, Andreas Wahner |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250089233
|
| Publikation (Nr.) |
 EGU/EGU2014-3429.pdf |
|
|
|
|
|
| Zusammenfassung |
| The hydroxyl (OH) radical is the main oxidant of atmospheric traces gases. The
quantification of its sources and sinks is necessary to fully comprehend the OH concentration.
Due to difficulties quantifying all the individual compounds contributing to the OH loss, the
direct quantification of the OH loss termed as the total OH reactivity is a crucial approach to
establish the budget of OH. Especially in forested areas, where OH reactivity is dominated by
highly reactive organic compounds, the directly measured total OH reactivity could not be
explained by individual trace gas measurements in recent field campaigns. This difference is
termed ‘missing reactivity’.
Here, we present OH reactivity data together with data of volatile organic compounds
(VOC) and other individual sinks of OH measured on board of the Zeppelin NT in
summer 2012. The campaign was part of the Pan-European Gas AeroSOls-climate
interaction Study (PEGASOS) and was performed from May to July 2012 in the area of
Rotterdam (the Netherlands) and Bologna (Italy). Total OH reactivity and VOC were
analyzed together with OH, HO2, CO, formaldehyde, NOx, HONO, ozone, photolysis
frequencies, particle number concentrations and meteorological parameters. For these
measurements the Zeppelin NT was flying at a low speed (50 km/h) and between altitudes
of 100 and 900 m above ground which enabled the investigation of the vertical
structure of the lower troposphere where most of the trace gas degradation takes
place.
On average, the total OH reactivity was 6.1 ± 1.2 s-1 over the area of Rotterdam and 3.8 ±
1.4 s-1 over the region of Bologna. During almost the entire campaign, the measured total
OH reactivity could be explained by the contributions of VOC and other measured species.
Only measurement in the nocturnal boundary layer, where anthropogenic emissions
were enriched, showed missing reactivity which could not be related to measured
compounds.
Oxygenated volatile organic compounds (OVOC) contributed the major part of the total OH
reactivity measured with a fraction of 30% over the Rotterdam Area and 40% over the area of
Bologna. In the morning hours when layered structures had been built up over night, large
gradients of the total OH reactivity were measured. The relative contribution of OVOC was
especially large in the residual layer which was decoupled from emissions from the
ground.
Acknowledgement: PEGASOS project funded by the European Commission und the
Framework Program7 (FP7-ENV-2010-265148). Part of the work was funded by the
Deutsche Forschungsgemeinschaft within priority program HALO (WE-4384/2-2). |
|
|
|
|
|
|