Naturally driven variability in the global secondary organic aerosol over a decade K. Tsigaridis1, J. Lathière2, M. Kanakidou1, and D. A. Hauglustaine2 1Environmental Chemical Processes Laboratory, Department of Chemistry, University of Crete, POBox 1470, 71409 Heraklion, Greece 2LSCE, CNRS/CEA, l’Orme-des-Merisiers, 91191 Gif-sur-Yvette, France
Abstract. In order to investigate the variability of the secondary organic aerosol
(SOA) distributions and budget and provide a measure for the robustness of
the conclusions on human induced changes of SOA, a global 3-dimensional
chemistry transport model describing both the gas and the particulate phase
chemistry of the troposphere has been applied. The response of the global
budget of SOA to temperature and moisture changes as well as to biogenic
emission changes over a decade (1984-1993) has been evaluated. The
considered emissions of biogenic non-methane volatile organic compounds
(VOC) are driven by temperature, light and vegetation. They vary between 756
and 810 Tg Cy-1 and are therefore about 5.5 times higher than the
anthropogenic VOC emissions. All secondary aerosols (sulphuric, nitrates and
organics) are computed on-line together with the aerosol associated water.
Over the studied decade, the computed natural variations (8%) in the
chemical SOA production from biogenic VOC oxidation equal the chemical SOA
production from anthropogenic VOC oxidation. Maximum values are calculated
for 1990 (warmer and drier) and minimum values for 1986 (colder and wetter).
The SOA computed variability results from a 7% increase in biogenic VOC
emissions from 1986 to 1990 combined with 8.5% and 6% increases in the
wet and dry deposition of SOA and leads to about 11.5% increase in the
SOA burden of biogenic origin. The present study also demonstrates the
importance of the hydrological cycle in determining the built up and fate of
SOA in the atmosphere. It also reveals the existence of significant positive
and negative feedback mechanisms in the atmosphere responsible for the non
linear relationship between emissions of biogenic VOC and SOA burden.
Citation: Tsigaridis, K., Lathière, J., Kanakidou, M., and Hauglustaine, D. A.: Naturally driven variability in the global secondary organic aerosol over a decade, Atmos. Chem. Phys., 5, 1891-1904, doi:10.5194/acp-5-1891-2005, 2005.