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| Titel |
Night-time aircraft measurements of OH and HO2 using the FAGE technique |
| VerfasserIn |
Hannah Bunyan, Trevor Ingham, Daniel Stone, Stewart Vaughan, Mathew Evans, Dwayne Heard |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048603
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| Zusammenfassung |
| The hydroxyl radical, OH, is the dominant tropospheric oxidant of trace gases during the
day, however, night-time oxidation is thought to be driven by the nitrate radical,
NO3. During the night, the reactions of ozone and NO3 with alkenes can lead to
night-time production of HOx (OH + HO2) radicals which can contribute to night-time
oxidation.
This night time chemistry was investigated during the Role of Night-time Chemistry in
Controlling the Oxidising Capacity of the Atmosphere (RONOCO) project during a series of
night-time flights over the UK made with the UK BAe146 research aircraft. The
RONOCO campaign included the first aircraft-based night-time measurements of OH
and HO2, made alongside measurements of the sum of RO2 radicals and the NO3
radical.
During the summer field campaign (16th to 30th July 2010) a comprehensive suite of
measurements was made over a period of eight flights, including the measurement of the
concentrations of OH and HO2 by the Leeds Aircraft FAGE instrument. Examples of these
measurements are presented here to illustrate aspects of night-time oxidative chemistry and to
demonstrate the capabilities of the aircraft FAGE instrument.
Preliminary data analysis indicates that the average HO2 concentration over the summer
field campaign was 3.7 Ã 107 molecule cm-3 (1.58 pptv), with concentrations of around 9
pptv observed during one flight.
Model calculations of OH and HO2, made using an observationally constrained zero
dimensional box model based on the Master Chemical Mechanism (MCM), are
compared to measurements and used to determine the processes controlling the
concentrations of OH and HO2, and to investigate night-time oxidation chemistry. |
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