The Impact of Black Carbon on Arctic Climate - Atmospheric Chemistry

Evolution <strong>of</strong> BC particles in the Arctic
<strong>Black</strong> carbon particles undergo transformation as they are
transported to the Arctic. Initially emitted as hydrophobic, they
are resistant to removal from the atmosphere through wet
deposition so that they are able to enter the free troposphere.
During transport, they grow through coagulation with other
particles and condensation <strong>of</strong> gas phase species.
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Transport
During transport, on a timescale <strong>of</strong> tens <strong>of</strong>
hours, aggregates form external mixtures
(1), which are hydrophilic. <strong>The</strong>se eventually,
after chemical mixing, form a mixture <strong>of</strong>
coated and internally mixed particles (2).
<strong>The</strong> radiative impact <strong>of</strong> these particles is
highly dependent on mixing state.
Emissions
During combustion
hundreds <strong>of</strong>
particles form
aggregates or chain
like structures.
Soot particle
An individual soot
particle <strong>of</strong> organized
graphitic layers has a
typical diameter <strong>of</strong>
~100 nm and is
hydrophobic.
3. Measurement and
modeling <strong>of</strong> black carbon
concentrations
3.1. Overview <strong>of</strong> BC measurements
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