Arctic marine secondary organic aerosol contributes significantly to summertime particle size distributions in the Canadian Arctic Archipelago

摘要: Abstract. Summertime Arctic aerosol size distributions are strongly controlled by natural regional emissions. Within this context, we use a chemical transport model with size-resolved microphysics (GEOS-Chem-TOMAS) to interpret measurements of from the Canadian Arctic Archipelago during summer 2016, as part “NETwork on Climate and Aerosols: Addressing key uncertainties in Remote Environments” (NETCARE) project. Our simulations suggest that condensation secondary organic aerosol (SOA) precursor vapors emitted and near Arctic marine (ice-free seawater) regions plays role particle growth events that shape observed at Alert (82.5 ∘  N, 62.3  W), Eureka (80.1  N, 86.4 and along NETCARE ship track within Archipelago. We refer SOA as Arctic marine (AMSOA) reflect marine-based likely biogenic sources for precursors condensing organic vapors. AMSOA simulated flux (500  µ g m - 2 day 1 , north of 50  N) (with an assumed yield unity) reduces the summertime distribution model–observation mean fractional error 2- 4-fold, relative simulation without AMSOA. Particle growth due condensable vapor contributes strongly (30 %–50 %) summertime-mean number particles with diameters larger than 20  nm study region. This couples with ternary nucleation (sulfuric acid, ammonia, water vapor) and biogenic sulfate account more 90 % this simulated number, which represents strong biogenic influence. The fit to summertime size-distribution observations is further improved and for by scaling up rate factor 100 to account other such gas-phase iodine and/or amines and/or fragmenting primary could be missing our simulations. Additionally, fits total aerosol concentrations 4  improve with the assumption contains semi-volatile species: the model–observation fractional error reduced 3-fold and ship distributions. accounts about half the simulated surface area volume summertime Canadian Archipelago, climate-relevant summertime pan-Arctic-mean top-of-the-atmosphere direct ( −0.04 W m−2 ) and cloud-albedo indirect −0.4 radiative effects, due to viewed order magnitude estimate. Future work should focus understanding summertime