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| Titel |
Vertical distribution of HOx concentrations driven by boundary layer dynamics |
| VerfasserIn |
Sebastian Gomm, Sebastian Broch, Hendrik Fuchs, Andreas Hofzumahaus, Frank Holland, Birger Bohn, Rolf Häseler, Julia Jäger, Jennifer Kaiser, Frank Keutsch, Xin Li, Keding Lu, Insa Lohse, Franz Rohrer, Ralf Tillmann, Robert Wegener, Glenn Wolfe, Thomas F. Mentel, Astrid Kiendler-Scharr, Andreas Wahner |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250088694
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| Publikation (Nr.) |
 EGU/EGU2014-7982.pdf |
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| Zusammenfassung |
| The hydroxyl (OH) and hydroperoxy (HO2) radicals are key compounds for the degradation
of pollutants in the atmosphere. Therefore, accurate and precise measurements
of HOx radicals (= OH + HO2) at different altitudes and in different regions are
necessary to test our understanding of atmospheric chemical processes. The planetary
boundary layer (PBL) is of special interest as it is chemically the most active part of
the atmosphere. Until today, there is a general lack of measurements investigating
the distribution of radicals, trace gases, and aerosols in the PBL with high spatial
resolution.
Here, we present results of measurements performed in June/July 2012 in the Po valley
region in Italy as part of the Pan-European Gas-AeroSOls-climate interaction Study
(PEGASOS). A Zeppelin NT was used as an airborne platform for measurements of HOx
radical concentrations and total OH reactivity (kOH) applying a remotely controlled Laser
Induced Fluorescence (LIF) instrument. In addition a comprehensive set of other trace gases
(O3, CO, NO, NO2, HCHO, HONO, VOCs), photolysis frequencies, particle number
concentration, and meteorological parameters were measured. During the morning hours, a
layered atmospheric structure with vertical gradients in trace gas concentrations was
observed. In altitudes larger than 600 m above ground, air masses with low trace gas
concentrations (NOx < 500 ppt, kOH < 3 s-1) were probed, whereas air masses in altitudes
below 100 m above ground were influenced by ground emissions resulting in higher trace gas
concentrations (NOx > 6 ppb, kOH > 6 s-1). The airship Zeppelin NT was used to perform
localized height profiles between 75 and 900 m above ground in order to investigate
the influence of these trace gas gradients on HOx radical concentrations. Due to
changing chemical conditions, the measured OH concentration shows a variability
with height up to a factor of 2.5 and for the measured HO2 concentration up to a
factor of 5. Additionally, we present box model calculations of HOx to identify
the processes driving the radical chemistry and its change in concentration with
height. |
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