Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 11, 11867-11894, 2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
30 Nov 2011
Detailed comparisons of airborne formaldehyde measurements with box models during the 2006 INTEX-B and MILAGRO campaigns: potential evidence for significant impacts of unmeasured and multi-generation volatile organic carbon compounds
A. Fried1, C. Cantrell2, J. Olson3, J. H. Crawford3, P. Weibring1, J. Walega1, D. Richter1, W. Junkermann4, R. Volkamer5, R. Sinreich5, B. G. Heikes6, D. O'Sullivan7, D. R. Blake8, N. Blake8, S. Meinardi8, E. Apel2, A. Weinheimer2, D. Knapp2, A. Perring9, R. C. Cohen9, H. Fuelberg10, R. E. Shetter2, S. R. Hall2, K. Ullmann2, W. H. Brune11, J. Mao12, X. Ren13, L. G. Huey14, H. B. Singh15, J. W. Hair16, D. Riemer13, G. Diskin17, and G. Sachse17 1The National Center for Atmospheric Research, Earth Observing Laboratory, 3450 Mitchell Lane, Boulder, CO, USA
2The National Center for Atmospheric Research, Atmospheric Chemistry Division, 3450 Mitchell Lane, Boulder, CO, USA
3NASA Langley Research Center, Hampton, VA, USA
4Karlsruhe Institute of Technology, IMK-IFU, Garmisch-Partenkirchen, Germany
5The University of Colorado, Dept. of Chemistry, Boulder, CO, USA
6The University of Rhode Island, Narragansett, RI, USA
7United States Naval Academy, Annapolis, MD, USA
8University of California, Irvine, Irvine, CA, USA
9University of California, Berkeley, Berkley, CA, USA
10Florida State University, Tallahassee, Florida, USA
11Pennsylvania State University, University Park, PA, USA
12Harvard University, Cambridge, MA, USA
13University of Miami, Miami, Fl, USA
14Georgia Institute of Technology, Atlanta, GA, USA
15NASA Ames Research, Moffett Field CA, USA
16NASA Lidar Applications Group, Langley Research Center, Hampton, VA, USA
17NASA Langley Research Center, Hampton, VA, USA
Abstract. Detailed comparisons of airborne CH2O measurements acquired by tunable diode laser absorption spectroscopy with steady state box model calculations were carried out using data from the 2006 INTEX-B and MILARGO campaign in order to improve our understanding of hydrocarbon oxidation processing. This study includes comparisons over Mexico (including Mexico City), the Gulf of Mexico, parts of the continental United States near the Gulf coast, as well as the more remote Pacific Ocean, and focuses on comparisons in the boundary layer. Select previous comparisons in other campaigns have highlighted some locations in the boundary layer where steady state box models have tended to underpredict CH2O, suggesting that standard steady state modeling assumptions might be unsuitable under these conditions, and pointing to a possible role for unmeasured hydrocarbons and/or additional primary emission sources of CH2O. Employing an improved instrument, more detailed measurement-model comparisons with better temporal overlap, up-to-date measurement and model precision estimates, up-to-date rate constants, and additional modeling tools based on both Lagrangian and Master Chemical Mechanism (MCM) runs, we have explained much of the disagreement between observed and predicted CH2O as resulting from non-steady-state atmospheric conditions in the vicinity of large pollution sources, and have quantified the disagreement as a function of plume lifetime (processing time). We show that in the near field (within ~4 to 6 h of the source), steady-state models can either over-or-underestimate observations, depending on the predominant non-steady-state influence. In addition, we show that even far field processes (10–40 h) can be influenced by non-steady-state conditions which can be responsible for CH2O model underestimations by ~20%. At the longer processing times in the 10 to 40 h range during Mexico City outflow events, MCM model calculations, using assumptions about initial amounts of high-order NMHCs, further indicate the potential importance of CH2O produced from unmeasured and multi-generation hydrocarbon oxidation compounds, particularly methylglyoxal, 3-hydroxypropanal, and butan-3-one-al.

Citation: Fried, A., Cantrell, C., Olson, J., Crawford, J. H., Weibring, P., Walega, J., Richter, D., Junkermann, W., Volkamer, R., Sinreich, R., Heikes, B. G., O'Sullivan, D., Blake, D. R., Blake, N., Meinardi, S., Apel, E., Weinheimer, A., Knapp, D., Perring, A., Cohen, R. C., Fuelberg, H., Shetter, R. E., Hall, S. R., Ullmann, K., Brune, W. H., Mao, J., Ren, X., Huey, L. G., Singh, H. B., Hair, J. W., Riemer, D., Diskin, G., and Sachse, G.: Detailed comparisons of airborne formaldehyde measurements with box models during the 2006 INTEX-B and MILAGRO campaigns: potential evidence for significant impacts of unmeasured and multi-generation volatile organic carbon compounds, Atmos. Chem. Phys., 11, 11867-11894,, 2011.
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