The sources of atmospheric black carbon at a European gateway to the ArcticDownload
Black carbon (BC) aerosols from incomplete combustion of biomass and fossil fuel contribute to Arctic climate warming. Models—seeking to advise mitigation policy—are challenged in reproducing observations of seasonally varying BC concentrations in the Arctic air. Here we compare year-round observations of BC and its d13C/D14C-diagnosed sources in Arctic Scandinavia, with tailored simulations from an atmospheric transport model. The model predictions for this European gateway to the Arctic are greatly improved when the emission inventory of anthropogenic sources is amended by satellite-derived estimates of BC emis- sions from fires. Both BC concentrations (R2=0.89, P<0.05) and source contributions (R2=0.77, P<0.05) are accurately mimicked and linked to predominantly European emis- sions. This improved model skill allows for more accurate assessment of sources and effects of BC in the Arctic, and a more credible scientific underpinning of policy efforts aimed at efficiently reducing BC emissions reaching the European Arctic.
Isotope-Based Source Apportionment of EC Aerosol Particles during Winter High-Pollution Events at the Zeppelin Observatory, Svalbard
Black carbon (BC) aerosol particles contribute
to climate warming of the Arctic, yet both the sources and the
source-related effects are currently poorly constrained.
Bottom-up emission inventory (EI) approaches are challenged
for BC in general and the Arctic in particular. For example,
estimates from three different EI models on the fractional
contribution to BC from biomass burning (north of 60° N)
vary between 11% and 68%, each acknowledging large
uncertainties. Here we present the first dual-carbon isotope-
based (Δ14C and δ13C) source apportionment of elemental
carbon (EC), the mass-based correspondent to optically
defined BC, in the Arctic atmosphere. It targeted 14 high-
loading and high-pollution events during January through
March of 2009 at the Zeppelin Observatory (79° N; Svalbard,
Norway), with these representing one-third of the total sampling period that was yet responsible for three-quarters of the total EC loading. The top-down source-diagnostic 14C fingerprint constrained that 52 ± 15% (n = 12) of the EC stemmed from biomass burning. Including also two samples with 95% and 98% biomass contribution yield 57 ± 21% of EC from biomass burning. Significant variability in the stable carbon isotope signature indicated temporally shifting emissions between different fossil sources, likely including liquid fossil and gas flaring. Improved source constraints of Arctic BC both aids better understanding of effects and guides policy actions to mitigate emissions.