400
G. Fanourgakis et al.
Organic aerosol concentrations are reduced with height despite the higher partitioning of the semi volatile organics into the aerosol phase at the lower temperatures
found in the middle troposphere than near the surface. Therefore, the contribution of
OA to CCN is the highest near the surface but remains important in the middle troposphere, although geographically restricted to the tropical continental regions and
their outflow. There, convection brings from the surface to the middle and high troposphere significant amounts of OA originating from primary and secondary biomass
burning sources or secondary formation from biogenic volatile organic compounds.
For instance, according to our calculations, on an annual mean basis the contribution
of OA to total CCN at 0.2% supersaturation at 500 hPa (around 5–6. Km height) in
the continental tropics remains very high, above 50%.
Acknowledgements This work has been supported by the European FP7 collaborative project
BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards
a Holistic UnderStanding. We acknowledge use of the ACTRIS database provided by Schmale, J.
and co-workers.
References
1. M. Kanakidou, J.H. Seinfeld, Pandis et al., Organic aerosol and global climate modelling: a
review. Atmos. Chem. Phys. 5(4), 1053–1123 (2005)
2. M. Kanakidou, R.A. Duce, J.M. Prospero et al., Atmospheric fluxes of organic N and P to the
global ocean. Global Biogeochem. Cycles 26(3), 1–12 (2012)
3. M.D. Petters, S.M. Kreidenweis, A. Sandu et al., A single parameter representation of hygroscopic growth and cloud condensation nucleus activity. Atmos. Chem. Phys. 7, 1961–1971
(2007)
4. J. Schmale, S. Henning, Henzing, et al., Collocated observations of cloud condensation nuclei,
particle size distributions, and chemical composition. Sci. Data 4, 170003 (2017)
5. E. Vignati, J. Wilson, P. Stier, M7: An efficient size-resolved aerosol microphysics module for
large-scale aerosol transport models. J. Geophys. Res. Atmos. 109(D22202) (2004)
6. N. Daskalakis, K. Tsigaridis, S. Myriokefalitakis, et al., Large gain in air quality compared to
an alternative anthropogenic emissions scenario. Atmos. Chem. Phys. 16, 9771–9784 (2016)
7. G.S. Fanourgakis, M. Kanakidou, A. Nenes, et al., Evaluation of global simulations of aerosol
particle and cloud condensation nuclei number, with implications for cloud droplet formation.
Atmos. Chem. Phys. 19, 8591–8617 (2019)
G. Fanourgakis et al.
Organic aerosol concentrations are reduced with height despite the higher partitioning of the semi volatile organics into the aerosol phase at the lower temperatures
found in the middle troposphere than near the surface. Therefore, the contribution of
OA to CCN is the highest near the surface but remains important in the middle troposphere, although geographically restricted to the tropical continental regions and
their outflow. There, convection brings from the surface to the middle and high troposphere significant amounts of OA originating from primary and secondary biomass
burning sources or secondary formation from biogenic volatile organic compounds.
For instance, according to our calculations, on an annual mean basis the contribution
of OA to total CCN at 0.2% supersaturation at 500 hPa (around 5–6. Km height) in
the continental tropics remains very high, above 50%.
Acknowledgements This work has been supported by the European FP7 collaborative project
BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards
a Holistic UnderStanding. We acknowledge use of the ACTRIS database provided by Schmale, J.
and co-workers.
References
1. M. Kanakidou, J.H. Seinfeld, Pandis et al., Organic aerosol and global climate modelling: a
review. Atmos. Chem. Phys. 5(4), 1053–1123 (2005)
2. M. Kanakidou, R.A. Duce, J.M. Prospero et al., Atmospheric fluxes of organic N and P to the
global ocean. Global Biogeochem. Cycles 26(3), 1–12 (2012)
3. M.D. Petters, S.M. Kreidenweis, A. Sandu et al., A single parameter representation of hygroscopic growth and cloud condensation nucleus activity. Atmos. Chem. Phys. 7, 1961–1971
(2007)
4. J. Schmale, S. Henning, Henzing, et al., Collocated observations of cloud condensation nuclei,
particle size distributions, and chemical composition. Sci. Data 4, 170003 (2017)
5. E. Vignati, J. Wilson, P. Stier, M7: An efficient size-resolved aerosol microphysics module for
large-scale aerosol transport models. J. Geophys. Res. Atmos. 109(D22202) (2004)
6. N. Daskalakis, K. Tsigaridis, S. Myriokefalitakis, et al., Large gain in air quality compared to
an alternative anthropogenic emissions scenario. Atmos. Chem. Phys. 16, 9771–9784 (2016)
7. G.S. Fanourgakis, M. Kanakidou, A. Nenes, et al., Evaluation of global simulations of aerosol
particle and cloud condensation nuclei number, with implications for cloud droplet formation.
Atmos. Chem. Phys. 19, 8591–8617 (2019)