B41I-05
Net Ecosystem Fluxes of Hydrocarbons from a Ponderosa Pine Forest in Colorado
Thursday, 17 December 2015: 09:00
2008 (Moscone West)
Robert C Rhew1, Andrew A Turnipseed2, John Victor Ortega3, James N Smith4, Alex B Guenther5, Steven Shen1, Luis Martinez6, Abigail Koss7, Carsten Warneke8 and Joost A De Gouw8, (1)University of California Berkeley, Berkeley, CA, United States, (2)2B Technologies, Boulder, CO, United States, (3)National Center for Atmospheric Research, Boulder, CO, United States, (4)NCAR, Boulder, CO, United States, (5)University of California Irvine, Irvine, CA, United States, (6)University of Texas at Brownsville, Brownsville, TX, United States, (7)University of Colorado at Boulder, Boulder, CO, United States, (8)NOAA Boulder, Boulder, CO, United States
Abstract:
Light (C2-C4) alkenes, light alkanes and isoprene (C5H8) are non-methane hydrocarbons that play important roles in the photochemical production of tropospheric ozone and in the formation of secondary organic aerosols. Natural terrestrial fluxes of the light hydrocarbons are poorly characterized, with global emission estimates based on limited field measurements. In 2014, net fluxes of these compounds were measured at the Manitou Experimental Forest Observatory, a semi-arid ponderosa pine forest in the Colorado Rocky Mountains and site of the prior BEACHON campaigns. Three field intensives were conducted between June 17 and August 10, 2014. Net ecosystem flux measurements utilized a relaxed eddy accumulation system coupled to an automated gas chromatograph. Summertime average emissions of ethene and propene were up to 90% larger than those observed from a temperate deciduous forest. Ethene and propene fluxes were also correlated to each other, similar to the deciduous forest study. Emissions of isoprene were small, as expected for a coniferous forest, and these fluxes were not correlated with either ethene or propene. Unexpected emissions of light alkanes were also observed, and these showed a distinct diurnal cycle. Understory flux measurements allowed for the partitioning of fluxes between the surface and the canopy. Full results from the three field intensives will be compared with environmental variables in order to parameterize the fluxes for use in modeling emissions.
