000187193 001__ 187193 000187193 005__ 20240712101040.0 000187193 0247_ $$2doi$$a10.5194/acp-14-8723-2014 000187193 0247_ $$2ISSN$$a1680-7316 000187193 0247_ $$2ISSN$$a1680-7324 000187193 0247_ $$2Handle$$a2128/8298 000187193 0247_ $$2WOS$$aWOS:000341991600029 000187193 0247_ $$2altmetric$$aaltmetric:21724650 000187193 037__ $$aFZJ-2015-00867 000187193 082__ $$a550 000187193 1001_ $$0P:(DE-HGF)0$$aHens, K.$$b0 000187193 245__ $$aObservation and modelling of HOx radicals in a boreal forest 000187193 260__ $$aKatlenburg-Lindau$$bEGU$$c2014 000187193 3367_ $$0PUB:(DE-HGF)16$$2PUB:(DE-HGF)$$aJournal Article$$bjournal$$mjournal$$s1422347398_24688 000187193 3367_ $$2DataCite$$aOutput Types/Journal article 000187193 3367_ $$00$$2EndNote$$aJournal Article 000187193 3367_ $$2BibTeX$$aARTICLE 000187193 3367_ $$2ORCID$$aJOURNAL_ARTICLE 000187193 3367_ $$2DRIVER$$aarticle 000187193 520__ $$aMeasurements of OH and HO2 radicals were conducted in a pine-dominated forest in southern Finland during the HUMPPA-COPEC-2010 (Hyytiälä United Measurements of Photochemistry and Particles in Air – Comprehensive Organic Precursor Emission and Concentration study) field campaign in summer 2010. Simultaneous side-by-side measurements of hydroxyl radicals were conducted with two instruments using chemical ionization mass spectrometry (CIMS) and laser-induced fluorescence (LIF), indicating small systematic disagreement, OHLIF / OHCIMS = (1.31 ± 0.14). Subsequently, the LIF instrument was moved to the top of a 20 m tower, just above the canopy, to investigate the radical chemistry at the ecosystem–atmosphere interface. Comprehensive measurements including observations of many volatile organic compounds (VOCs) and the total OH reactivity were conducted and analysed using steady-state calculations as well as an observationally constrained box model.Production rates of OH calculated from measured OH precursors are consistent with those derived from the steady-state assumption and measured total OH loss under conditions of moderate OH reactivity. The primary photolytic sources of OH contribute up to one-third to the total OH production. OH recycling, which occurs mainly by HO2 reacting with NO and O3, dominates the total hydroxyl radical production in this boreal forest. Box model simulations agree with measurements for hydroxyl radicals (OHmod. / OHobs. = 1.00 ± 0.16), while HO2 mixing ratios are significantly under-predicted (HO2mod. / HO2obs. = 0.3 ± 0.2), and simulated OH reactivity does not match the observed OH reactivity. The simultaneous under-prediction of HO2 and OH reactivity in periods in which OH concentrations were simulated realistically suggests that the missing OH reactivity is an unaccounted-for source of HO2.Detailed analysis of the HOx production, loss, and recycling pathways suggests that in periods of high total OH reactivity there are additional recycling processes forming OH directly, not via reaction of HO2 with NO or O3, or unaccounted-for primary HOx sources. Under conditions of moderate observed OH reactivity and high actinic flux, an additional RO2 source of approximately 1 × 106 molec cm−3 s−1 would be required to close the radical budget. Nevertheless, a major fraction of the OH recycling occurs via the reaction of HO2 with NO and O3 in this terpene-dominated environment. 000187193 536__ $$0G:(DE-HGF)POF2-233$$a233 - Trace gas and aerosol processes in the troposphere (POF2-233)$$cPOF2-233$$fPOF II$$x0 000187193 588__ $$aDataset connected to CrossRef, juser.fz-juelich.de 000187193 7001_ $$0P:(DE-HGF)0$$aNovelli, A.$$b1 000187193 7001_ $$0P:(DE-HGF)0$$aMartinez, M.$$b2 000187193 7001_ $$0P:(DE-HGF)0$$aAuld, J.$$b3 000187193 7001_ $$0P:(DE-HGF)0$$aAxinte, R.$$b4 000187193 7001_ $$0P:(DE-Juel1)2693$$aBohn, B.$$b5$$ufzj 000187193 7001_ $$0P:(DE-HGF)0$$aFischer, H.$$b6 000187193 7001_ $$0P:(DE-HGF)0$$aKeronen, P.$$b7 000187193 7001_ $$0P:(DE-HGF)0$$aKubistin, D.$$b8 000187193 7001_ $$0P:(DE-HGF)0$$aNölscher, A. C.$$b9 000187193 7001_ $$0P:(DE-HGF)0$$aOswald, R.$$b10 000187193 7001_ $$0P:(DE-HGF)0$$aPaasonen, P.$$b11 000187193 7001_ $$0P:(DE-HGF)0$$aPetäjä, T.$$b12 000187193 7001_ $$0P:(DE-HGF)0$$aRegelin, E.$$b13 000187193 7001_ $$0P:(DE-HGF)0$$aSander, R.$$b14 000187193 7001_ $$0P:(DE-HGF)0$$aSinha, V.$$b15 000187193 7001_ $$0P:(DE-HGF)0$$aSipilä, M.$$b16 000187193 7001_ $$0P:(DE-HGF)0$$aTaraborrelli, D.$$b17 000187193 7001_ $$0P:(DE-HGF)0$$aTatum Ernest, C.$$b18 000187193 7001_ $$0P:(DE-HGF)0$$aWilliams, J.$$b19 000187193 7001_ $$0P:(DE-HGF)0$$aLelieveld, J.$$b20 000187193 7001_ $$0P:(DE-HGF)0$$aHarder, H.$$b21 000187193 773__ $$0PERI:(DE-600)2069847-1$$a10.5194/acp-14-8723-2014$$gVol. 14, no. 16, p. 8723 - 8747$$n16$$p8723 - 8747$$tAtmospheric chemistry and physics$$v14$$x1680-7324$$y2014 000187193 8564_ $$uhttps://juser.fz-juelich.de/record/187193/files/FZJ-2015-00867.pdf$$yOpenAccess 000187193 8564_ $$uhttps://juser.fz-juelich.de/record/187193/files/FZJ-2015-00867.jpg?subformat=icon-144$$xicon-144$$yOpenAccess 000187193 8564_ $$uhttps://juser.fz-juelich.de/record/187193/files/FZJ-2015-00867.jpg?subformat=icon-180$$xicon-180$$yOpenAccess 000187193 8564_ $$uhttps://juser.fz-juelich.de/record/187193/files/FZJ-2015-00867.jpg?subformat=icon-640$$xicon-640$$yOpenAccess 000187193 909CO $$ooai:juser.fz-juelich.de:187193$$pdnbdelivery$$pVDB$$pVDB:Earth_Environment$$pdriver$$popen_access$$popenaire 000187193 915__ $$0LIC:(DE-HGF)CCBY3$$2HGFVOC$$aCreative Commons Attribution CC BY 3.0 000187193 915__ $$0StatID:(DE-HGF)0150$$2StatID$$aDBCoverage$$bWeb of Science Core Collection 000187193 915__ $$0StatID:(DE-HGF)0100$$2StatID$$aJCR 000187193 915__ $$0StatID:(DE-HGF)9905$$2StatID$$aIF >= 5 000187193 915__ $$0StatID:(DE-HGF)0500$$2StatID$$aDBCoverage$$bDOAJ 000187193 915__ $$0StatID:(DE-HGF)0200$$2StatID$$aDBCoverage$$bSCOPUS 000187193 915__ $$0StatID:(DE-HGF)0110$$2StatID$$aWoS$$bScience Citation Index 000187193 915__ $$0StatID:(DE-HGF)0111$$2StatID$$aWoS$$bScience Citation Index Expanded 000187193 915__ $$0StatID:(DE-HGF)0510$$2StatID$$aOpenAccess 000187193 915__ $$0StatID:(DE-HGF)1150$$2StatID$$aDBCoverage$$bCurrent Contents - Physical, Chemical and Earth Sciences 000187193 915__ $$0StatID:(DE-HGF)0300$$2StatID$$aDBCoverage$$bMedline 000187193 915__ $$0StatID:(DE-HGF)0199$$2StatID$$aDBCoverage$$bThomson Reuters Master Journal List 000187193 9141_ $$y2014 000187193 9101_ $$0I:(DE-588b)5008462-8$$6P:(DE-Juel1)2693$$aForschungszentrum Jülich GmbH$$b5$$kFZJ 000187193 9132_ $$0G:(DE-HGF)POF3-243$$1G:(DE-HGF)POF3-240$$2G:(DE-HGF)POF3-200$$aDE-HGF$$bMarine, Küsten- und Polare Systeme$$lAtmosphäre und Klima$$vTropospheric trace substances and their transformation processes$$x0 000187193 9131_ $$0G:(DE-HGF)POF2-233$$1G:(DE-HGF)POF2-230$$2G:(DE-HGF)POF2-200$$3G:(DE-HGF)POF2$$4G:(DE-HGF)POF$$aDE-HGF$$bErde und Umwelt$$lAtmosphäre und Klima$$vTrace gas and aerosol processes in the troposphere$$x0 000187193 920__ $$lyes 000187193 9201_ $$0I:(DE-Juel1)IEK-8-20101013$$kIEK-8$$lTroposphäre$$x0 000187193 9801_ $$aFullTexts 000187193 980__ $$ajournal 000187193 980__ $$aVDB 000187193 980__ $$aUNRESTRICTED 000187193 980__ $$aFullTexts 000187193 980__ $$aI:(DE-Juel1)IEK-8-20101013 000187193 981__ $$aI:(DE-Juel1)ICE-3-20101013