[1] The composition of Arctic aerosol, especially during the springtime Arctic haze, may play an important role in the radiative balance of the Arctic. The contribution of organic components to Arctic haze has only recently been investigated. Because measurements in this region are sparse, little is known about organic particle composition, sources, and concentrations. This study compares springtime measurements in the Arctic regions north of the Atlantic (ICEALOT, 2008) and Pacific (Barrow, Alaska, 2008 and oceans. The aerosol organic functional group composition from Fourier transform infrared (FTIR) spectroscopy combined with positive matrix factorization (PMF) and elemental tracer analysis indicate that mixed combustion sources account for more than 60% (>0.3 mg m −3 ) of the submicron organic mass (OM 1 ) for springtime haze conditions in both regions. Correlations with typical combustion tracers (S, Zn, K, Br, V) provide evidence for the contribution of combustion sources to the Arctic OM 1 . However, the two regions are influenced by different urban and industrial centers with different fuel usage. High-sulfur coal burning in northeastern Europe impacts the northern Atlantic Arctic region, while oil burning and forest fires in northeastern Asia and Alaska impact the northern Pacific Arctic region. Quadrupole and High Resolution Aerosol Mass Spectrometry measurements confirm the highly oxygenated nature of the OM 1 , with an oxygenated organic aerosol (OOA) spectrum from PMF. High co-emissions of sulfate and organics from coal-burning in northeastern Europe produce significant concentrations of organosulfate functional groups that account for 10% of OM 1 measured by FTIR spectroscopy during ICEALOT. These observations provide preliminary support for a heterogeneous mechanism of organosulfate formation on acidic sulfate particles.

at Barrow, Alaska, to characterize the organic mass (OM) in the Arctic aerosol. Organic functional group concentrations and trace metals were measured with FTIR on submicron particles collected on Teflon filters. The OM varied from 0.07 mg m −3 in summer to 0.43 mg m −3 in winter, and 0.35 mg m − 3 in spring, showing a transition in OM composition between spring and winter. Most of the OM in spring could be attributed to anthropogenic sources, consisting primarily of alkane and carboxylic acid functional groups and correlated to elemental tracers of industrial pollution, biomass burning, and shipping emissions. PMF analysis associated OM with two factors, a Mixed Combustion factor (MCF) and an Ocean-derived factor (ODF). Back trajectory analysis revealed that the highest fractions of the MCF were associated with air masses that had originated from northeastern Asia and the shipping lanes south of the Bering Straits. The ODF consisted of organic hydroxyl groups and correlated with organic and inorganic seawater components. The ODF accounted for more than 55% of OM in winter when the sampled air masses originated along the coastal and lake regions of the Northwest Territories of Canada. Frost flowers with organic-salt coatings that arise by brine rejection during sea ice formation may account for this large source of carbohydrate-like OM during the icecovered winter season. While the anthropogenic sources contributed more than 0.3 mg m −3 of the springtime haze OM, ocean-derived particles provided comparable OM sources in winter. Citation: Shaw, P. M., L. M. Russell, A. Jefferson, and P. K. Quinn (2010), Arctic organic aerosol measurements show particles from mixed combustion in spring haze and from frost flowers in winter, Geophys.

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