New insights into aerosol and climate in the Arctic
2018
Abstract. Motivated by the need to predict how the
Arcticatmosphere will change in a warming world, this article summarizes recent advances made by the research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) that contribute to our fundamental understanding of
Arcticaerosol particles as they relate to climate forcing. The overall goal of NETCARE research has been to use an interdisciplinary approach encompassing extensive field observations and a range of chemical transport,
earth system, and biogeochemical models. Several major findings and advances have emerged from NETCARE since its formation in 2013 . (1) Unexpectedly high summertime
dimethyl sulfide(DMS) levels were identified in ocean water and the overlying atmosphere in the Canadian
ArcticArchipelago (CAA). Furthermore,
melt ponds, which are widely prevalent, were identified as an important DMS source. (2) Evidence was found of widespread particle nucleation and growth in the marine boundary layer in the CAA in the summertime. DMS-oxidation-driven nucleation is facilitated by the presence of atmospheric ammonia arising from sea
bird colonyemissions, and potentially also from coastal regions,
tundra, and biomass burning. Via accumulation of secondary organic material (SOA), a significant fraction of the new particles grow to sizes that are active in cloud droplet formation. Although the gaseous precursors to
Arcticmarine SOA remain poorly defined, the measured levels of common continental SOA precursors (isoprene and monoterpenes) were low, whereas elevated mixing ratios of oxygenated volatile organic compounds were inferred to arise via processes involving the
sea surface microlayer. (3) The variability in the vertical distribution of
black carbon(BC) under both springtime
Arctic hazeand more pristine summertime aerosol conditions was observed. Measured particle size distributions and mixing states were used to constrain, for the first time, calculations of aerosol–
climateinteractions under
Arcticconditions. Aircraft- and ground-based measurements were used to better establish the BC source regions that supply the
Arcticvia long-range transport mechanisms. (4) Measurements of ice nucleating particles (INPs) in the
Arcticindicate that a major source of these particles is
mineral dust, likely derived from local sources in the summer and long-range transport in the spring. In addition, INPs are abundant in the
sea surface microlayerin the
Arctic, and possibly play a role in ice nucleation in the atmosphere when
mineral dustconcentrations are low. (5) Amongst multiple aerosol components, BC was observed to have the smallest effective deposition velocities to high
Arcticsnow.
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