Estimating the atmospheric concentration of Criegee intermediates and their possible interference in a FAGE-LIF instrument
We analysed the extensive dataset from the HUMPPA-COPEC 2010 and the HOPE 2012 field campaigns in the boreal forest and rural environments of Finland and Germany, respectively, and estimated the abundance of stabilised Criegee intermediates (SCIs) in the lower troposphere. Based on laboratory te...
| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-06-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/17/7807/2017/acp-17-7807-2017.pdf |
| Summary: | We analysed the extensive dataset from the
HUMPPA-COPEC 2010 and the HOPE 2012 field campaigns in the boreal forest and
rural environments of Finland and Germany, respectively, and estimated the
abundance of stabilised Criegee intermediates (SCIs) in the lower troposphere.
Based on laboratory tests, we propose that the background OH signal observed
in our IPI-LIF-FAGE instrument during the aforementioned campaigns is caused
at least partially by SCIs. This hypothesis is based on observed correlations
with temperature and with concentrations of unsaturated volatile organic
compounds and ozone. Just like SCIs, the background OH concentration can be
removed through the addition of sulfur dioxide. SCIs also add to the
previously underestimated production rate of sulfuric acid. An average
estimate of the SCI concentration of ∼ 5.0 × 10<sup>4</sup> molecules cm<sup>−3</sup>
(with an order of magnitude uncertainty) is calculated for the two
environments. This implies a very low ambient concentration of SCIs, though,
over the boreal forest, significant for the conversion of SO<sub>2</sub> into
H<sub>2</sub>SO<sub>4</sub>. The large uncertainties in these calculations, owing to the
many unknowns in the chemistry of Criegee intermediates, emphasise the need
to better understand these processes and their potential effect on the
self-cleaning capacity of the atmosphere. |
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| ISSN: | 1680-7316 1680-7324 |