References

ACP

Atmospheric Chemistry and Physics

ACP

1680-7324

Copernicus GmbH

Göttingen, Germany

10.5194/acp-13-2031-2013

Evaluation of HOx sources and cycling using measurement-constrained model calculations in a 2-methyl-3-butene-2-ol (MBO) and monoterpene (MT) dominated ecosystem

Kim

¹ ⁷ Wolfe

G. M.

² ⁸ ⁹ Mauldin

¹ ¹⁰ ¹¹ Cantrell

¹ Guenther

¹ Karl

¹ Turnipseed

¹ Greenberg

¹ Hall

S. R.

¹ Ullmann

¹ Apel

¹ Hornbrook

¹ Kajii

³ ¹² Nakashima

³ ¹³ Keutsch

F. N.

² DiGangi

J. P.

² Henry

S. B.

² Kaser

⁴ Schnitzhofer

⁴ Graus

⁵ ⁶ Hansel

⁴ Zheng

¹ Flocke

F. F.

ACD/NESL/NCAR Boulder, CO 80301, USA

Department of Chemistry, University of Wisconsin, Madison, WI, USA

Division of Applied Chemistry, Tokyo Metropolitan University, Tokyo

University of Innsbruck, Innsbruck, Austria

CIRES, University of Colorado, Boulder, CO 80309 USA

Chemical Science Division, ESRL-NOAA, Boulder, CO 80305, USA

now at: Department of Earth System Science, University of California, Irvine, CA, USA

now at: Joint Center for Earth Systems Technology, Baltimore County, MD USA

now at: NASA Goddard Space Flight Center, Greenbelt, MD, USA

now at: Department of Physics, University of Helsinki, Helsinki, Finland

now at: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO, USA

now at: Graduate School of Environmental Studies and Human and Environmental Studies, Kyoto University, Kyoto, Japan

now at: Department of Environmental and Natural Resource Sciences, Tokyo University of Agriculture and Technology, Tokyo, Japan

21 02 2013

13 4 2031 2044

This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

This article is available from http://www.atmos-chem-phys.net/13/2031/2013/acp-13-2031-2013.html

The full text article is available as a PDF file from http://www.atmos-chem-phys.net/13/2031/2013/acp-13-2031-2013.pdf

We present a detailed analysis of OH observations from the BEACHON (Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics and Nitrogen)-ROCS (Rocky Mountain Organic Carbon Study) 2010 field campaign at the Manitou Forest Observatory (MFO), which is a 2-methyl-3-butene-2-ol (MBO) and monoterpene (MT) dominated forest environment. A comprehensive suite of measurements was used to constrain primary production of OH via ozone photolysis, OH recycling from HO2, and OH chemical loss rates, in order to estimate the steady-state concentration of OH. In addition, the University of Washington Chemical Model (UWCM) was used to evaluate the performance of a near-explicit chemical mechanism. The diurnal cycle in OH from the steady-state calculations is in good agreement with measurement. A comparison between the photolytic production rates and the recycling rates from the HO2 + NO reaction shows that recycling rates are ~20 times faster than the photolytic OH production rates from ozone. Thus, we find that direct measurement of the recycling rates and the OH loss rates can provide accurate predictions of OH concentrations. More importantly, we also conclude that a conventional OH recycling pathway (HO2 + NO) can explain the observed OH levels in this non-isoprene environment. This is in contrast to observations in isoprene-dominated regions, where investigators have observed significant underestimation of OH and have speculated that unknown sources of OH are responsible. The highly-constrained UWCM calculation under-predicts observed HO2 by as much as a factor of 8. As HO2 maintains oxidation capacity by recycling to OH, UWCM underestimates observed OH by as much as a factor of 4. When the UWCM calculation is constrained by measured HO2, model calculated OH is in better agreement with the observed OH levels. Conversely, constraining the model to observed OH only slightly reduces the model-measurement HO2 discrepancy, implying unknown HO2 sources. These findings demonstrate the importance of constraining the inputs to, and recycling within, the ROx radical pool (OH + HO2 + RO2).

References 1

Alaghmand, M., Shepson, P. B., Starn, T. K., Jobson, B. T., Wallace, H. W., Carroll, M. A., Bertman, S. B., Lamb, B., Edburg, S. L., Zhou, X., Apel, E., Riemer, D., Stevens, P., and Keutsch, F.: The morning NOx maximum in the forest atmosphere boudary layer, Atmos. Chem. Phys. Discuss., 11, 29251–29282, http://dx.doi.org/10.5194/acpd-11-29251-2011doi:10.5194/acpd-11-29251-2011, 2011.

Apel, E. C., Riemer, D. D., Hills, A., Baugh, W., Orlando, J., Faloona, I., Tan, D., Brune, W., Lamb, B., Westberg, H., Carroll, M. A., Thornberry, T., and Geron, C. D.: Measurement and interpretation of isoprene fluxes and isoprene, methacrolein, and methyl vinyl ketone mixing ratios at the PROPHET site during the 1998 intensive, J. Geophys. Res.-Atmos., 107, 4034 doi10.1029/2000jd000225, 2002.

Archibald, A. T., Jenkin, M. E., and Shallcross, D. E.: An isoprene mechanism intercomparison, Atmos. Environ., 44, 5356–5364, http://dx.doi.org/10.1016/j.atmosenv.2009.09.016doi:10.1016/j.atmosenv.2009.09.016, 2010.

Atkinson, R.: Atmospheric chemistry of VOCs and NO$_\text x$, Atmos. Environ., 34, 2063–2100, 2000.

Carslaw, N., Creasey, D. J., Harrison, D., Heard, D. E., Hunter, M. C., Jacobs, P. J., Jenkin, M. E., Lee, J. D., Lewis, A. C., Pilling, M. J., Saunders, S. M., and Seakins, P. W.: OH and HO2 radical chemistry in a forested region of north-western Greece, Atmos. Environ., 35, 4725–4737, http://dx.doi.org/10.1016/s1352-2310(01)00089-9doi:10.1016/s1352-2310(01)00089-9, 2001.

Chameides, W. L. and Cicerone, R. J.: Effects of nonmethane hydrocarbons in atmosphere, J. Geophys. Res.-Ocean. Atmos., 83, 947–952, http://dx.doi.org/10.1029/JC083iC02p00947doi:10.1029/JC083iC02p00947, 1978.

Crounse, J. D., Paulot, F., Kjaergaard, H. G., and Wennberg, P. O.: Peroxy radical isomerization in the oxidation of isoprene, Phys. Chem. Chem. Phys., 13, 13607–13613, 2011.

Crutzen, P. J.: Photochemical reactions initiated by and influencing ozone in unpolluted tropospheric air, Tellus, 26, 47–57, 1974.

de Gouw, J. and Warneke, C.: Measurements of volatile organic compounds in the earths atmosphere using proton-transfer-reaction mass spectrometry, Mass Spectrom. Rev., 26, 223–257, 2007.

Di Gangi, J., Boyle, E. S., Karl, T., Turnipseed, A., Kim, S., Cantrell, C., Mauldin, R. L., Zheng, W., Flocke, F., Hall, S. R., Ullmann, K., Nakashima, Y., Paul, J. G., Wolfe, G. M., Desai, A. R., Kajii, Y., Guenther, A., and Keutsch, F.: First direct measurements of formaldehyde flux via eddy covariance: Implications for missing in-canopy formaldehyde sources, Atmos. Chem. Phys., 11, 10565–10578, http://dx.doi.org/10.5194/acp-11-10565-2011doi:10.5194/acp-11-10565-2011, 2011.

DiGangi, J. P., Henry, S. B., Kammrath, A., Boyle, E. S., Kaser, L., Schnitzhofer, R., Graus, M., Turnipseed, A., Park, J.-H., Weber, R. J., Hornbrook, R., Cantrell, C., Maudlin, R. L., III, Kim, S., Nakashima, Y., Wolfe, G. M., Kajii, Y., Apel, E., Goldstein, A. H., Guenther, A., Karl, T., Hansel, A., and Keutsch, F. N.: Observations of glyoal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry, Atmos. Chem. Phys., 12, 9529–5943, http://dx.doi.org/10.5194/acp-12-9529-2012doi:10.5194/acp-12-9529-2012, 2012.

Edwards, G. D., Cantrell, C. A., Stephens, S., Hill, B., Goyea, O., Shetter, R. E., Mauldin, R. L., Kosciuch, E., Tanner, D. J., and Eisele, F. L.: Chemical ionization mass spectrometer instrument for the measurement of tropospheric HO2 and RO2, Analyt. Chem., 75, 5317–5327, 2003.

Eisele, F. L. and Tanner, D. J.: Ion-assisted tropospheric OH measurements, J. Geophys. Res.-Atmos., 96, 9295–9308, http://dx.doi.org/10.1029/91jd00198doi:10.1029/91jd00198, 1991.

Fuchs, H., Bohn, B., Hofzumahaus, A., Holland, F., Lu, K., Nehr, S., Rohrer, F., and Wahner, A.: Detection of HO2 by laser-induced fluorescence: Calibration and interferences from RO2 radicals, Atmos. Meas. Tech., 4, 1209–1225, http://dx.doi.org/10.5194/amt-4-1209-2011doi:10.5194/amt-4-1209-2011, 2011.

Fuchs, H., Dorn, H.-P., Bachner, M., Bohn, B., Brauers, T., Gomm, S., Hofzumahaus, A., Holland, F., Nehr, S., Rohrer, F., Tillmann, R., and Wahner, A.: Comparison of oh concentration measurements by DOAS and LIF during SAPHIR chamber experiments at high OH reactivity and low NO concentrations, Atmos. Meas. Tech., 5, 1611–1626, http://dx.doi.org/10.5194/amt-5-1611-2012doi:10.5194/amt-5-1611-2012, 2012.

Graus, M., Muller, M., and Hansel, A.: High resolution PTR-TOF: Quantification and formula confirmation of VOC in real time, J. Am. Soc. Mass Spectrom., 21, 1037–1044, 2010.

Heard, D. E. and Pilling, M. J.: Measurement of OH and HO2 in the troposphere, Chem. Rev., 103, 5163–5198, http://dx.doi.org/10.1021/cr020522sdoi:10.1021/cr020522s, 2003.

Hofzumahaus, A., Rohrer, F., Lu, K. D., Bohn, B., Brauers, T., Chang, C. C., Fuchs, H., Holland, F., Kita, K., Kondo, Y., Li, X., Lou, S. R., Shao, M., Zeng, L. M., Wahner, A., and Zhang, Y. H.: Amplified trace gas removal in the troposphere, Science, 324, 1702–1704, http://dx.doi.org/10.1126/science.1164566doi:10.1126/science.1164566, 2009.

Hornbrook, R. S., Crawford, J., Edwards, G. D., Goyea, O., Mauldin, R. L., Olson, J. S., and Cantrell, C. A.: Measurements of tropospheric HO2 and RO2 by oxygen dilution modulation and chemical ionization mass spectrometry, Atmos. Meas. Tech., 4, 735–756, http://dx.doi.org/10.5194/amt-4-735-2011doi:10.5194/amt-4-735-2011, 2011.

Huisman, A. J., Hottle, J. R., Coenes, K. L., Di Gangi, J. P., Galloway, M. M., Kammrath, A., and Keutsch, F. N.: Laser-induced phosphorescence for the in situ detection of glyoxal at part per trillion mixing ratios, Analyt. Chem., 80, 5584–5591, 2008.

Jenkin, M. E., Saunders, S. M., and Pilling, M. J.: The tropospheric degradation of volatile organic compounds: A protocol for mechanism development, Atmos. Environ.. 31, 81–104, http://dx.doi.org/10.1016/s1352-2310(96)00105-7doi:10.1016/s1352-2310(96)00105-7, 1997.

Jenkin, M. E., Saunders, S. M., and Pilling, M. J.: The tropospheric degradation of volatile organic compounds: A protocol for mechanism development, Atmos. Environ., 31, 81–104, 1997.

Junkermann, F., Platt, U., and Volz-Thomas, A.: A photoelectric detector for the measurement of photolysis frequencies of ozone and other atmospheric molecules, J. Atmos. Chem., 8, 203–227, 1989.

Kaser, L., Karl, T., Schnitzhofer, R., Graus, M., Herdlinger-Blatt, I. S., DiGangi, J. P., Sive, B., Turnipseed, A., Hornbrook, R. S., Zheng, W., Flocke, F. M., Guenther, A., Keutsch, F. N., Apel, E., and Hansel, A.: Comparison of different real time VOC measurement techniques in a ponderosa pine forest, Atmos. Chem. Phys. Discuss., 12, 27955–27988, http://dx.doi.org/10.5194/acpd-12-27955-2012doi:10.5194/acpd-12-27955-2012, 2012.

Kim, S., Karl, T., Guenther, A., Tyndall, G., Orlando, J., Harley, P., Rasmussen, R., and Apel, E.: Emissions and ambient distributions of biogenic volatile organic compounds (BVOCs) in a ponderosa pine ecosystem: Interpretation of PTR-MS mass spectra, Atmos. Chem. Phys., 10, 1759–1771, http://dx.doi.org/10.5194/acp-10-1759-2010doi:10.5194/acp-10-1759-2010, 2010.

Lelieveld, J., Butler, T. M., Crowley, J. N., Dillon, T. J., Fischer, H., Ganzeveld, L., Harder, H., Lawrence, M. G., Martinez, M., Taraborrelli, D., and Williams, J.: Atmospheric oxidation capacity sustained by a tropical forest, Nature, 452, 737–740, http://dx.doi.org/10.1038/nature06870doi:10.1038/nature06870, 2008.

Levy, H.: Normal atmosphere – large radical and formaldehyde concentrations predicted, Science, 173, 141–143, http://dx.doi.org/10.1126/science.173.3992.141doi:10.1126/science.173.3992.141, 1971.

Levy, H.: Photochemistry of lower troposphere, Planet Space Sci., 20, 919–935, http://dx.doi.org/10.1016/0032-0633(72)90177-8doi:10.1016/0032-0633(72)90177-8, 1972.

Logan, J. A., Prather, M. J., Wofsy, S. C., and McElroy, M. B.: Tropospheric chemistry – a global perspective, J. Geophys. Res.-Ocean. Atmos., 86, 7210–7254, http://dx.doi.org/10.1029/JC086iC08p07210doi:10.1029/JC086iC08p07210, 1981.

Lou, S., Holland, F., Rohrer, F., Lu, K., Bohn, B., Brauers, T., Chang, C. C., Fuchs, H., Haseler, R., Kita, K., Kondo, Y., Li, X., Shao, M., Zeng, L., Wahner, A., Zhang, Y., Wang, W., and Hofzumahaus, A.: Atmospheric OH reactivities in the Pearl River Delta – China in summer 2006: Measurement and model results, Atmos. Chem. Phys., 10, 11243–11260, http://dx.doi.org/10.5194/acp-10-11243-2010doi:10.5194/acp-10-11243-2010, 2010.

Lovelock, J. E.: Methyl chloroform in troposphere as an indicator of OH radical abundance, Nature, 267, 32–32, http://dx.doi.org/10.1038/267032a0doi:10.1038/267032a0, 1977.

Lu, K. D., Rohrer, F., Holland, F., Fuchs, H., Bohn, B., Brauers, T., Chang, C. C., Haseler, R., Hu, M., Kita, K., Kondo, Y., Li, X., Lou, S. R., Nehr, S., Shao, M., Zeng, L. M., Wahner, A., Zhang, Y. H., and Hofzumahaus, A.: Observation and modelling of OH and HO2 concentrations in the Pearl River Delta 2006: A missing oh source in a voc rich atmosphere, Atmos. Chem. Phys., 12, 1541–1569, http://dx.doi.org/10.5194/acp-12-1541-2012doi:10.5194/acp-12-1541-2012, 2012.

Mao, J., Ren, X., Zhang, L., Van Duin, D. M., Cohen, R. C., Park, J.-H., Goldstein, A. H., Paulot, F., Beaver, M. R., Crounse, J. D., Wennberg, P. O., DiGangi, J. P., Henry, S. B., Keutsch, F. N., Park, C., Schade, G. W., Wolfe, G. M., Thornton, J. A., and Brune, W. H.: Insights into hydroxyl measurements and atmospheric oxidation in a california forest, Atmos. Chem. Phys., 12, 8009–8020, http://dx.doi.org/10.5194/acp-12-8009-2012doi:10.5194/acp-12-8009-2012, 2012.

Mauldin, R. L., Berndt, T., Sipila, M., Paasonen, P., Petaja, T., Kim, S., Kurten, T., Stratmann, F., Kerminen, V. M., and Kulmala, M.: A new atmospherically relevant oxidant of sulphur dioxide, Nature, 488, 193–196, http://dx.doi.org/10.1038/nature11278doi:10.1038/nature11278, 2012.

Mauldin, R. L., Kosciuch, E., Eisele, F. L., Huey, L. G., Tanner, D. J., Sjostedt, S. J., Blake, D., Chen, G., Crawford, J., and Davis, D.: South pole Antarctica observations and modeling results:New insights on HO$_\text x$ radical and sulfur chemistry, Atmos. Environ., 44, 572–581, 2010.

Nakashima, Y., Ida, A., Kajii, Y., Greenberg, J., Karl, T., Kim, S., Turnipseed, A., Guenther, A., Di Ganigi, J., Henry, J., Keutsch, F., Schnitzhofer, R., Kaser, L., and Hansel, A.: Total OH reactivity measurements at manitou experimental forest in summer season during beachon-rocs field campaign, American Geophysical Union Fall Meeting, San Francisco, CA USA, 2011.

Nakashima, Y., Ida, A., Kajii, Y. J., Greenberg, J., Karl, T., Kim, S., Turnipseed, A., Guenther, A. B., DiGangi, J. P., Henry, S. B., Keutsch, F. N., Schnitzhofer, R., Kaser, L., and Hansel, A.: Total OH reactivity measurements at the Manitou Experimental Forest in summer season during BEACHON-ROCS campaign, Atmos. Chem. Phys., in preparation, 2013.

Nolscher, A. C., Williams, J., Sinha, V., Custer, T., Song, W., Johnson, A. M., Axinte, R., Bozem, H., Fischer, H., Pouvesle, N., Phillips, G., Crowley, J. N., Rantala, P., Rinne, J., Kulmala, M., Gonzales, D., Valverde-Canossa, J., Vogel, A., Hoffmann, T., Ouwesloot, H. G., Vila-Guerau de Arellano, J., and Lelieveld, J.: Summertime total oh reactivity measurements from boreal forst during HUMPPA-COPEC 2010, Atmos. Chem. Phys., 12, 8257–8270, http://dx.doi.org/10.5194/acp-12-8257-2012doi:10.5194/acp-12-8257-2012, 2012.

Peeters, J. and Müller, J. F.: HO$_\text x$ radical regeneration in isoprene oxidation via peroxy radical isomerisations. II: experimental evidence and global impact, Phys. Chem. Chem. Phys., 12, 14227–14235, 2010.

Peeters, J., Nguyen, T. L., and Vereecken, L.: HO$_\text x$ radical regeneration in the oxidation of isoprene, Phys. Chem. Chem. Phys., 11, 5935–5939, 2009.

Petaja, T., Mauldin, R. L., Kosciuch, E., McGrath, J., Nieminen, T., Paasonen, P., Boy, M., Adamov, A., Kotiaho, T., and Kulmala, M.: Sulfuric acid and OH concentrations in a boreal forest site, Atmos. Chem. Phys., 9, 7435–7448, http://dx.doi.org/10.5194/acp-9-7435-2009doi:10.5194/acp-9-7435-2009, 2009.

Ren, X., Mao, J., Brune, W., Cantrell, C., Maudlin, R. L., Hornbrook, R., Kosciuch, E., Olson, J. R., Crawford, J., Chen, G., and Singh, H. B.: Airbonre intercomparison of HO$_\text x$ measurements using laser-induced fuorescence and chemical ionization mass spectrometer during ARCTAS, Atmos. Meas. Tech., 5, 2025–2037, http://dx.doi.org/10.5194/gmd-5-2025-2012doi:10.5194/gmd-5-2025-2012, 2012.

Sadanaga, Y., Yoshino, A., Watanabe, K., Yoshioka, A., Wakazono, Y., Kanaya, Y., and Kajii, Y.: Development of a measurement system of OH reactivity in the atmosphere by using a laser-induced pump and probe tehcnqiue, Rev. Sci. Instr., 75, 2648–2655, 2004.

Saunders, S. M., Jenkin, M. E., Derwent, R. G., and Pilling, M. J.: Protocol for the development of the Master Chemical Mechanism, MCM v3 (Part A): tropospheric degradation of non-aromatic volatile organic compounds, Atmos. Chem. Phys., 3, 161–180, http://dx.doi.org/10.5194/acp-3-161-2003doi:10.5194/acp-3-161-2003, 2003.

Sinha, V., Williams, J., Lelieveld, J., Ruuskanen, T. M., Kajos, M. J., Patokoski, J., Helllen, H., Hakola, H., Mogensen, D., Boy, M., Rinne, J., and Kulmala, M.: OH reactivity measurements within a Boreal Forest: Evidence for unknown reactive emissions, Environ. Sci. Technol., 44, 6614–6620, 2010.

Singh, H. B.: Atmospheric halocarbons - evidence in favor of reduced average hydroxyl radical concentration in troposphere, Geophys. Res. Lett., 4, 101–104, http://dx.doi.org/10.1029/GL004i003p00101doi:10.1029/GL004i003p00101, 1977.

Sjostedt, S. J.: Investigation of photochemistry at high latitudes: Comparison of model predictions to measurements of short lived species, Ph. D., Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, USA, 174 pp., 2006.

Slusher, D. L., Huey, L. G., Tanner, D. J., Flocke, F., and Roberts, J. M.: A thermal dissociation-chemical ionization mass spectrometry (TD-CIMS) technique for the simultaneous measurement of peroxyacyl nitrates and dinitrogen pentoxide, J. Geophys. Res., 109, D19315, http://dx.doi.org/10.1029/2004JD004670doi:10.1029/2004JD004670, 2004.

Stavrakou, T., Peeters, J., and Müller, J.-F.: Improved global modelling of HO$_\text x$ recycling in isoprene oxidation: evaluation against the GABRIEL and INTEX-A aircraft campaign measurements, Atmos. Chem. Phys., 10, 9863–9878, http://dx.doi.org/10.5194/acp-10-9863-2010doi:10.5194/acp-10-9863-2010, 2010.

Tan, D., Faloona, I., Simpas, J. B., Brune, W., Shepson, P. B., Couch, T. L., Sumner, A. L., Carroll, M. A., Thornberry, T., Apel, E., Riemer, D., and Stockwell, W.: HO$_\text x$ budgets in a deciduous forest: Results from the PROPHET summer 1998 campaign, J. Geophys. Res.-Atmos., 106, 24407–24427, http://dx.doi.org/10.1029/2001jd900016doi:10.1029/2001jd900016, 2001.

Tanner, D. J., Jefferson, A., and Eisele, F. L.: Selected ion chemical ionization mass spectrometric measurement of OH, J. Geophys. Res.-Atmos., 102, 6415–6425, http://dx.doi.org/10.1029/96jd03919doi:10.1029/96jd03919, 1997.

Whalley, L. K., Edwards, P. M., Furneaux, K. L., Goddard, A., Ingham, T., Evans, M. J., Stone, D., Hopkins, J. R., Jones, C. E., Karunaharan, A., Lee, J. D., Lewis, A. C., Monks, P. S., Moller, S. J., and Heard, D. E.: Quantifying the magnitude of a missing hydroxyl radical source in a tropical rainforest, Atmos. Chem. Phys., 11, 7223–7233, http://dx.doi.org/10.5194/acp-11-7223-2011doi:10.5194/acp-11-7223-2011, 2011.

Wofsy, S. C., McConnel, J. C., and McElroy, M. B.: Atmospheric CH4, CO, and CO2, J. Geophys. Res., 77, 4477–4493, http://dx.doi.org/10.1029/JC077i024p04477doi:10.1029/JC077i024p04477, 1972.

Wolfe, G. M. and Thornton, J. A.: The Chemistry of Atmosphere-Forest Exchange (CAFE) Model – Part 1: Model description and characterization, Atmos. Chem. Phys., 11, 77–101, http://dx.doi.org/10.5194/acp-11-77-2011doi:10.5194/acp-11-77-2011, 2011.

Wolfe, G. M., Crounse, J. D., Parrish, J. D., St. Clair, J. M., Beaver, M. R., Paulot, F., Yoon, T. P., Wennberg, P. O., and Keutsch, F. N.: Photolysis, OH reactivity and ozone reactivity of a proxy for isoprene-derived hydroperoxyenals (HPALDs), Phys. Chem. Chem. Phys., 14, 7276–7286, http://dx.doi.org/10.1039/C2CP40388Adoi:10.1039/C2CP40388A, 2012.