Emission and Chemical Transformation of Biogenic Volatile Organic Compounds

ECHO

From 01/2002 to 03/2004

Staff: Jens-Christopher Mayer, Christoph Thomas, Michael Kortner

Forests are complex sources of biogenic volatile organic compounds (VOC) in the planetary boundary layer. Previous studies estimate that global emissions of biogenic VOC are in the range of 490 Tg C/year to 1150 Tg C/year and thus a factor of 5 to 10 higher than anthropogenic emissions. Therefore, biogenic VOC contribute significantly to the formation of photo-oxidants in the troposphere. Due to fast vertical transport processes, they may even have an impact on the chemistry of the upper troposphere. Recent airborne measurements show surprisingly high mixing ratios of reactive compounds such as acetone, formaldehyde, methanol, hydrogen peroxide and organic hydroperoxides. These compounds are believed to originate from primary biogenic emissions or to be oxidation products of biogenic VOC. All together, the impact of biogenic VOC on tropospheric photochemistry, air quality, and the formation of secondary products affecting our climate on a regional and global scale are far from being understood. A considerable lack of knowledge exists concerning a typical forest stand as a net source of reactive trace compounds, the amount of primary emitted VOC which are transported directly into the PBL, and the amount of VOC which are chemically processed within the canopy, the products of which are transported into the PBL. The gas phase chemistry above the canopy which is driven by high concentrations of reactive precursor compounds and high UV radiation is also not yet understood. The goal of the proposed project is to investigate these questions to improve our understanding of biosphere-atmosphere interactions and effects on the planetary boundary layer.

Homepage: http://www.fz-juelich.de/icg/icg-ii/echo

List of publications of this Project

Thomas, C; Mayer, JC; Meixner, FX; Foken, T: Analysis of the low-frequency turbulence above tall vegetation using a Doppler sodar, Boundary-Layer Meteorology, 119, 563-587 (2006), doi:10.1007/s10546-005-9038-0 -- Details

• ECHO final report

Related links:

• Diploma Thesis: Characterisation of the Atmospheric Boundary-Layer in a Complex Terrain using SODAR-RASS
• Experiment: ECHO: ECHO Field Campains in 2002 and 2003
• PhD Thesis: Detection and analysis of coherent structures within and above tall-vegetated canopies