 |
| Titel |
Missing gas-phase source of HONO inferred from Zeppelin measurements in the troposphere |
| VerfasserIn |
Xin Li, Franz Rohrer, Andreas Hofzumahaus, Theo Brauers, Rolf Häseler, Birger Bohn, Sebastian Broch, Hendrik Fuchs, Sebastian Gomm, Frank Holland, Julia Jäger, Jennifer Kaiser, Frank N. Keutsch, Insa Lohse, Ralf Tillmann, Robert Wegener, 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 |
250092900
|
| Publikation (Nr.) |
 EGU/EGU2014-7265.pdf |
|
|
|
|
|
| Zusammenfassung |
| Nitrous acid (HONO) is an important trace gas in the atmosphere due to its contribution to
the cycles of nitrogen oxides (NOX) and hydrogen oxides (HOX). In the past decades,
ground-based observations of HONO around the world showed much higher daytime
concentrations than can be explained by the known gas-phase chemistry (i.e., HONO + hν -
OH + NO, HONO + OH - NO2 + H2O, OH + NO + M - HONO + M). Different
light-dependent reactions on ground surfaces have been proposed as additional daytime
HONO sources. However, due to lack of measurements, little is known about the
concentrations of HONO and its sources in the planetary boundary layer (PBL) at higher
altitudes above the earth’s surface.
The airship Zeppelin NT is an ideal platform to investigate the chemistry and
dynamics of the PBL. During the PEGASOS field campaigns in 2012 and 2013, HONO
and its gas-phase sources and sinks were measured simultaneously on-board the
airship Zeppelin NT, for the lowest 1 km of the PBL. In the upper part of the altitude
range during morning hours, when the airmass is still isolated from processes at the
earth’s surface by the remaining nocturnal boundary layer, we find unexpectedly
large concentrations of HONO which can neither be explained by heterogeneous
reactions on aerosol and ground surfaces, nor by known gas-phase reactions. Our
observations show evidence for an unknown gas-phase light-dependent HONO
production which dominates the overall HONO formation in the lower troposphere.
This new HONO source requires NOX and possibly OH or HO2 radicals. As a
result, the general impact of HONO on the OH formation is likely overestimated. |
|
|
|
|
|
|