Journal Article

PreJuSER-20058

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png HOx budgets during HOxComp: A case study of HOx chemistry under NOx-limited conditions

Elshorbany, Y. F. ; Kleffmann, J. ; Hofzumahaus, A.FZJ* ; Kurtenbach, R. ; Wiesen, P. ; Brauers, T.FZJ* ; Bohn, B.FZJ* ; Dorn, H.-P.FZJ* ; Fuchs, H.FZJ* ; Holland, F.FZJ* ; Rohrer, F.FZJ* ; Tillmann, R.FZJ* ; Wegener, R.FZJ* ; Wahner, A.FZJ* ; Kanaya, Y. ; Yoshino, A. ; Hishida, S. ; Kajii, Y. ; Martinez, M. ; Kubistin, D. ; Harder, H. ; Lelieveld, J. ; Elste, T. ; Plass-Dülmer, C. ; Stange, G. ; Berresheim, H. ; Schurath, U.

2012
Union Washington, DC

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Please use a persistent id in citations: http://hdl.handle.net/2128/20909  doi:10.1029/2011JD017008

Abstract: Recent studies have shown that measured OH under NOx-limited, high-isoprene conditions are many times higher than modeled OH. In this study, a detailed analysis of the HOx radical budgets under low-NOx, rural conditions was performed employing a box model based on the Master Chemical Mechanism (MCMv3.2). The model results were compared with HOx radical measurements performed during the international HOxComp campaign carried out in Julich, Germany, during summer 2005. Two different air masses influenced the measurement site denoted as high-NOx (NO, 1-3 ppbv) and low-NOx (NO, < 1 ppbv) periods. Both modeled OH and HO2 diurnal profiles lay within the measurement range of all HOx measurement techniques, with correlation slopes between measured and modeled OH and HO2 around unity. Recently discovered interference in HO2 measurements caused by RO2 cross sensitivity was found to cause a 30% increase in measured HO2 during daytime on average. After correction of the measured HO2 data, the model HO2 is still in good agreement with the observations at high NOx but overpredicts HO2 by a factor of 1.3 to 1.8 at low NOx. In addition, for two different set of measurements, a missing OH source of 3.6 +/- 1.6 and 4.9 +/- 2.2 ppb h(-1) was estimated from the experimental OH budget during the low-NOx period using the corrected HO2 data. The measured diurnal profile of the HO2/OH ratio, calculated using the corrected HO2, is well reproduced by the MCM at high NOx but is significantly overestimated at low NOx. Thus, the cycling between OH and HO2 is better described by the model at high NOx than at low NOx. Therefore, similar comprehensive field measurements accompanied by model studies are urgently needed to investigate HOx recycling under low-NOx conditions.

Keyword(s): J

Note: This work was supported by the EU FP-6 program EUROCHAMP (Integration of European Simulation Chambers for Investigating Atmospheric Processes, grant RII3-CT-2004-505968) and ACCENT (Priority 1.1.6.3. Global Change and Ecosystems, grant GOCECT-2004-505337). We thank F. J. Johnen for assistance with the experiments.

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Contributing Institute(s):

1. Troposphäre (IEK-8)

Research Program(s):

1. Atmosphäre und Klima (P23)

Appears in the scientific report 2012

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Database coverage:
; ; Current Contents - Agriculture, Biology and Environmental Sciences ; Current Contents - Social and Behavioral Sciences ; JCR ; NCBI Molecular Biology Database ; SCOPUS ; Science Citation Index ; Science Citation Index Expanded ; Thomson Reuters Master Journal List ; Web of Science Core Collection

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