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. © 2011 Author(s).
CITATION STYLE
Digangi, J. P., Boyle, E. S., Karl, T., Harley, P., Turnipseed, A., Kim, S., … Keutsch, F. N. (2011). First direct measurements of formaldehyde flux via eddy covariance: Implications for missing in-canopy formaldehyde sources. Atmospheric Chemistry and Physics, 11(20), 10565–10578. https://doi.org/10.5194/acp-11-10565-2011
Mendeley helps you to discover research relevant for your work.