Soot aging time scales in polluted regions during day and night

by N. Riemer, H. Vogel, B. Vogel
Atmospheric Chemistry and Physics ()
Get full text at journal

Abstract

The aging of soot is one of the key uncertainties in the estimation of both the direct and indirect climate effect. While freshly emitted soot is initially hydrophobic and externally mixed, it can be transferred into an internal mixture by coagulation, condensation or photochemical processes. These aging processes affect the hygroscopic qual- ities and hence the growth behaviour, the optical properties and eventually the lifetime of the soot particles. However, due to computational limits the aging of soot in global cli- mate models is often only parameterised by an estimated turnover rate resulting in a lifetime of soot of several days. Hence, the aging process of soot is one of the key uncertainties governing the burden and effect of black carbon. In this study, we discuss the time scale on which diesel soot is transferred from an external to an internal mixture based on the results of our simulations with a comprehensive mesoscale model. For daytime conditions during summer condensation of sulphuric acid is dominant and the aging process occurs on a time scale of τ=8 h close to the sources and τ=2 h above the source region. During winter comparable time scales are found but ammonium nitrate becomes more important. During night time condensation is not effective. Then coagulation is the most important aging process and our results show time scales between 10 h and 40 h.

Cite this document (BETA)

Readership Statistics

27 Readers on Mendeley
by Discipline
 
37% Earth and Planetary Sciences
 
22% Chemistry
 
19% Environmental Science
by Academic Status
 
26% Researcher
 
26% Student > Ph. D. Student
 
19% Student > Master
by Country
 
7% United States
 
4% Germany
 
4% Ireland

Sign up today - FREE

Mendeley saves you time finding and organizing research. Learn more

  • All your research in one place
  • Add and import papers easily
  • Access it anywhere, anytime

Start using Mendeley in seconds!

Sign up & Download

Already have an account? Sign in