TY  - JOUR
AU  - Acton, W. J. F.
AU  - Schallhart, S.
AU  - Langford, B.
AU  - Valach, A.
AU  - Rantala, P.
AU  - Fares, S.
AU  - Carriero, G.
AU  - Tillmann, R.
AU  - Tomlinson, S. J.
AU  - Dragosits, U.
AU  - Gianelle, D.
AU  - Hewitt, C. N.
AU  - Nemitz, E.
TI  - Canopy-scale flux measurements and bottom-up emission estimates of volatile organic compounds from a mixed oak and hornbeam forest in northern Italy
JO  - Atmospheric chemistry and physics / Discussions
VL  - 15
IS  - 20
SN  - 1680-7375
CY  - Katlenburg-Lindau
PB  - EGU
M1  - FZJ-2015-06992
SP  - 29213 - 29264
PY  - 2015
AB  - This paper reports the fluxes and mixing ratios of biogenically emitted volatile organic compounds (BVOCs) 4 m above a mixed oak and hornbeam forest in northern Italy. Fluxes of methanol, acetaldehyde, isoprene, methyl vinyl ketone + methacrolein, methyl ethyl ketone and monoterpenes were obtained using both a proton transfer reaction-mass spectrometer (PTR-MS) and a proton transfer reaction-time of flight-mass spectrometer (PTR-ToF-MS) together with the methods of virtual disjunct eddy covariance (PTR-MS) and eddy covariance (PTR-ToF-MS). Isoprene was the dominant emitted compound with a mean day-time flux of 1.9 mg m-2 h-1. Mixing ratios, recorded 4 m above the canopy, were dominated by methanol with a mean value of 6.2 ppbv over the 28 day measurement period. Comparison of isoprene fluxes calculated using the PTR-MS and PTR-ToF-MS showed very good agreement while comparison of the monoterpene fluxes suggested a slight over estimation of the flux by the PTR-MS. A basal isoprene emission rate for the forest of 1.7 mg m-2 h-1 was calculated using the MEGAN isoprene emissions algorithms (Guenther et al., 2006). A detailed tree species distribution map for the site enabled the leaf-level emissions of isoprene and monoterpenes recorded using GC-MS to be scaled up to produce a "bottom-up" canopy-scale flux. This was compared with the "top-down" canopy-scale flux obtained by measurements. For monoterpenes, the two estimates were closely correlated and this correlation improved when the plant species composition in the individual flux footprint was taken into account. However, the bottom-up approach significantly underestimated the isoprene flux, compared with the top-down measurements, suggesting that the leaf-level measurements were not representative of actual emission rates.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.5194/acpd-15-29213-2015
UR  - https://juser.fz-juelich.de/record/278667
ER  -