Research article
26 Oct 2011
Research article | 26 Oct 2011
First direct measurements of formaldehyde flux via eddy covariance: implications for missing in-canopy formaldehyde sources
J. P. DiGangi1, E. S. Boyle1, T. Karl2, P. Harley2, A. Turnipseed2, S. Kim2, C. Cantrell2, R. L. Maudlin III3,*,2, W. Zheng2, F. Flocke2, S. R. Hall2, K. Ullmann2, Y. Nakashima6, J. B. Paul4, G. M. Wolfe1, A. R. Desai5, Y. Kajii6, A. Guenther2, and F. N. Keutsch1
J. P. DiGangi et al.
J. P. DiGangi1, E. S. Boyle1, T. Karl2, P. Harley2, A. Turnipseed2, S. Kim2, C. Cantrell2, R. L. Maudlin III3,*,2, W. Zheng2, F. Flocke2, S. R. Hall2, K. Ullmann2, Y. Nakashima6, J. B. Paul4, G. M. Wolfe1, A. R. Desai5, Y. Kajii6, A. Guenther2, and F. N. Keutsch1
- 1Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
- 2Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO, USA
- 3Department of Physics, University of Helsinki, Finland
- 4Thermo Fisher Scientific, Redwood City, CA, USA
- 5Department of Atmospheric & Oceanic Sciences, University of Wisconsin-Madison, Madison, WI, USA
- 6Division of Applied Chemistry, Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, Japan
- *now at: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO, USA
- 1Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
- 2Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, CO, USA
- 3Department of Physics, University of Helsinki, Finland
- 4Thermo Fisher Scientific, Redwood City, CA, USA
- 5Department of Atmospheric & Oceanic Sciences, University of Wisconsin-Madison, Madison, WI, USA
- 6Division of Applied Chemistry, Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, Japan
- *now at: Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO, USA
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Received: 13 Jun 2011 – Discussion started: 30 Jun 2011 – Revised: 05 Oct 2011 – Accepted: 12 Oct 2011 – Published: 26 Oct 2011
We report the first observations of formaldehyde (HCHO) flux measured via eddy covariance, as well as HCHO concentrations and gradients, as observed by the Madison Fiber Laser-Induced Fluorescence Instrument during the BEACHON-ROCS 2010 campaign in a rural, Ponderosa Pine forest northwest of Colorado Springs, CO. A median noon upward flux of ~80 μg m−2 h−1 (~24 pptv m s−1) was observed with a noon range of 37 to 131 μg m−2 h−1. Enclosure experiments were performed to determine the HCHO branch (3.5 μg m-2 h−1) and soil (7.3 μg m−2 h−1) direct emission rates in the canopy. A zero-dimensional canopy box model, used to determine the apportionment of HCHO source and sink contributions to the flux, underpredicted the observed HCHO flux by a factor of 6. Simulated increases in concentrations of species similar to monoterpenes resulted in poor agreement with measurements, while simulated increases in direct HCHO emissions and/or concentrations of species similar to 2-methyl-3-buten-2-ol best improved model/measurement agreement. Given the typical diurnal variability of these BVOC emissions and direct HCHO emissions, this suggests that the source of the missing flux is a process with both a strong temperature and radiation dependence.
