HO<sub>x</sub> measurements in the summertime upper troposphere over Europe: a comparison of observations to a box model and a 3-D model
In situ airborne measurements of OH and HO<sub>2</sub> with the HORUS (HydrOxyl Radical measurement Unit based on fluorescence Spectroscopy) instrument were performed in the summertime upper troposphere across Europe during the HOOVER 2 (HO<sub>x</sub> OVer EuRope) campaign i...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2013-11-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/13/10703/2013/acp-13-10703-2013.pdf |
| Summary: | In situ airborne measurements of OH and HO<sub>2</sub> with the HORUS (HydrOxyl
Radical measurement Unit based on fluorescence Spectroscopy) instrument were
performed in the summertime upper troposphere across Europe during the HOOVER
2 (HO<sub>x</sub> OVer EuRope) campaign in July 2007. Complementary
measurements of trace gas species and photolysis frequencies were conducted
to obtain a broad data set, which has been used to quantify the significant
HO<sub>x</sub> sources and sinks. In this study we compare the in situ
measurement of OH and HO<sub>2</sub> with simulated mixing ratios from the
constrained box model CAABA/MECCA (Chemistry As A Box Model
Application/Module Efficiently Calculating the Chemistry of the Atmosphere),
and the global circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry
Model). The constrained box model reproduces the observed OH and HO<sub>2</sub>
mixing ratios with better agreement (obs/mod median 98% OH, 96%
HO<sub>2</sub>) than the global model (median 76% OH, 59% HO<sub>2</sub>). The
observations and the computed HO<sub>x</sub> sources and sinks are used to
identify deviations between the models and their impacts on the calculated
HO<sub>x</sub> budget. |
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| ISSN: | 1680-7316 1680-7324 |