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| Titel |
Airborne measurements of nitrous acid and its budget in the planetary boundary layer |
| VerfasserIn |
Xin Li, Rolf Häseler, Theo Brauers, Franz Rohrer, Andreas Hofzumahaus, Birger Bohn, Sebastian Broch, Hendrik Fuchs, Sebastian Gomm, Frank Holland, Insa Lohse, Ralf Tillmann, Thomas F. Mentel, Astrid Kiendler-Scharr, Andreas Wahner |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075521
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| 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, most
HONO observations were performed at ground level, and only a few HONO gradient
measurements were reported for the lowest 100Â m of the planetary boundary layer (PBL). In
most field measurements, it is found that the ambient HONO concentrations cannot be
explained by the known gas-phase chemistry alone. Additional HONO production
is needed, and heterogeneous production at ground and on aerosol surfaces was
proposed.
Within the framework of PEGASOS, an instrument for ambient HONO measurement
using the LOPAP technique was setup together with instruments measuring HOX radicals,
NOX, photolysis frequencies, and other parameters on board the airship Zeppelin NT. During
two field campaigns in the Netherlands and in Italy, HONO and its gas phase sources and
sinks were measured continuously in each flight, covering the altitude range from ground to
1Â km. The measured daytime HONO mixing ratios ranged from 50Â ppt to 1.2Â ppb with
an average value of 140Â ppt. While a strong HONO gradient was found in early
morning hours, it was vanishing with the breakup of the nocturnal boundary layer.
Elevated HONO to NOX ratios were observed at higher altitudes, indicating an
enhanced HONO production. HONO simulations using a 1-D model indicate that the
HONO production at higher altitudes cannot be explained by known processes,
neither by gas-phase reactions nor by vertical mixing of HONO produced at ground
surface. Therefore, in addition to the current knowledge of the atmospheric HONO
budget, other HONO formation pathways are need to explain the field observations. |
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