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Evolution of Size Distributions with condensation of sulfuric acid on particles
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Used Condensation Size Distribution Model from
http://aerosols.ucsd.edu/aerosolsinmotion.html to
determine the growth of the three distributions
• Included the Condensation Rate Equation (Eq. 11.29
from Seinfeld and Pandis).
Stevanovic et al., 2013 and Zhu et al., 2013 both had initial
distributions predominantly in Aitken and accumulation
mode (appx. diameter 0.1 μm). The condensation of
sulfuric acid did not affect the diameter size because the
diameter was large relative to the amount of vapor
condensed.
Su et al., 2013 measured particles in nucleation mode
(diameter of 0.001-0.01 μm), thus the condensation of
sulfuric acid had a greater affect on mean diameter size.
Evolution of Size Distributions with condensation of sulfuric acid on particles
Reference Paper
Stevanovic et al., 2013
Zhu et al., 2011
Su et al., 2013
Time to condense sulfuric acid to 50% of initial particle mass
>576 hours (24 days)
>576 hours (24 days)
194-195 hours (~8days)
Motivation:
Conclusions:
Coggon et al., 2012 measured marine aerosols and the affects of • The particles in the accumulation mode and larger half of Aitken
ship impacts during the E-PEACE campaign. Measurements of in
mode are less affected by the condensation of sulfuric acid than
cloud aerosols contained almost a 1:1 ratio of sulfate to the organic
particles in nucleation mode.
component (47% sulfate).
• Su et al., 2013 contained particles in nucleation and Aitken mode,
Approach:
thus it took approximately 8 days to grow particles to a 1:1 ratio
To simulate condensation of sulfuric acid onto particles, particles
of sulfuric acid to organics.
from initial size distributions were assumed to be composed of 100%
organics and the Condensation Model was run.
• Zhu et al., 2011 and Stevanovic et al., 2013 contained particles in
Result:
Particles emitted at <0.10 μm in diameter are composed of a larger
fraction sulfuric acid than particles ≥0.10 μm in diameter.
the upper bound of Aitken mode and accumulation mode,
however, even after condensation of sulfuric acid persisted for 24
days, the ratio of sulfuric acid to organics did not reach 1:1, but
rather 0.65:1.