HONO Measurements in Barrow, Alaska; using LOPAP technique
Abstract
Nitrous acid (HONO) is an important precursor of the hydroxyl radical (OH) the “cleaning detergent” of the atmosphere. Recent polar studies indicate the existence of a strong surface source of HONO over snow and ice surfaces which can affect the oxidation capacity of the polar atmosphere. However, the mechanism of nitrous acid formation is still under discussion. In addition, from modeling of experimental field data it was recently proposed that high measured HONO levels may be caused, at least in part, by strong interferences of chemical instruments used in polar studies. These high interferences were recently also observed by a LOPAP instrument under simulated polar conditions on the mountain “Jungfraujoch” in the Swiss Alps. In the present study mixing ratios of HONO were measured during the OASIS campaign in Barrow, Alaska from 13th March - 14th April, 2009. The measurements were done with an optimized ultra sensitive Long Path Absorption Photometer (LOPAP), which has two channels in series, correcting for interferences. In addition, sampling artifacts in sampling lines are minimized by the use of an external sampling unit. Mixing ratios were in the range from below detection limit (DL= 0.4 pptV) to ~500 pptV with an average of 27 pptV. The very high concentrations observed were caused by strong emissions from combustion sources close to the field site (City of Barrow and the BARC research complex). For typical clean days the diurnal profile during the campaign was as expected, i.e. low mixing ratios during the night and high mixing ratios during the day which can be explained by photochemical sources.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFM.A31C0114V
- Keywords:
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- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry;
- 0368 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: constituent transport and chemistry;
- 0394 ATMOSPHERIC COMPOSITION AND STRUCTURE / Instruments and techniques