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

Medientyp: E-Artikel

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

Beteiligte: Croft, Betty; Martin, Randall V.; Leaitch, W. Richard; Burkart, Julia; Chang, Rachel Y.-W.; Collins, Douglas B.; Hayes, Patrick L.; Hodshire, Anna L.; Huang, Lin; Kodros, John K.; Moravek, Alexander; Mungall, Emma L.; Murphy, Jennifer G.; Sharma, Sangeeta; Tremblay, Samantha; Wentworth, Gregory R.; Willis, Megan D.; Abbatt, Jonathan P. D.; Pierce, Jeffrey R.

Erschienen: Copernicus GmbH, 2019

Sprache: Englisch

DOI: 10.5194/acp-19-2787-2019

ISSN: 1680-7324

Entstehung:

Anmerkungen:

Beschreibung: Abstract. Summertime Arctic aerosol size distributions are strongly controlled bynatural regional emissions. Within this context, we use a chemical transportmodel with size-resolved aerosol microphysics (GEOS-Chem-TOMAS) to interpretmeasurements of aerosol size distributions from the Canadian ArcticArchipelago during the summer of 2016, as part of the “NETwork on Climateand Aerosols: Addressing key uncertainties in Remote Canadian Environments”(NETCARE) project. Our simulations suggest that condensation of secondary organicaerosol (SOA) from precursor vapors emitted in the Arctic and near Arcticmarine (ice-free seawater) regions plays a key role in particle growth eventsthat shape the aerosol size distributions observed at Alert (82.5∘ N,62.3∘ W), Eureka (80.1∘ N, 86.4∘ W), andalong a NETCARE ship track within the Archipelago. We refer to this SOA asArctic marine SOA (AMSOA) to reflect the Arctic marine-based and likelybiogenic sources for the precursors of the condensing organic vapors. AMSOA from a simulated flux (500 µgm-2day-1, north of50∘ N) of precursor vapors (with an assumed yield of unity) reduces thesummertime particle size distribution model–observation mean fractionalerror 2- to 4-fold, relative to a simulation without this AMSOA. Particlegrowth due to the condensable organic vapor flux contributes strongly(30 %–50 %) to the simulated summertime-mean number of particles withdiameters larger than 20 nm in the study region. This growth couples withternary particle nucleation (sulfuric acid, ammonia, and water vapor) andbiogenic sulfate condensation to account for more than 90 % of thissimulated particle number, which represents a strong biogenic influence. The simulated fit tosummertime size-distribution observations is further improved at Eureka andfor the ship track by scaling up the nucleation rate by a factor of 100 toaccount for other particle precursors such as gas-phase iodine and/or aminesand/or fragmenting primary particles that could be missing from oursimulations. Additionally, the fits to the observed size distributions and totalaerosol number concentrations for particles larger than 4 nm improve withthe assumption that the AMSOA contains semi-volatile species: themodel–observation mean fractional error is reduced 2- to 3-fold for the Alert andship track size distributions. AMSOA accounts for about half of thesimulated particle surface area and volume distributions in the summertimeCanadian Arctic Archipelago, with climate-relevant simulated summertimepan-Arctic-mean top-of-the-atmosphere aerosol direct (−0.04 W m−2) andcloud-albedo indirect (−0.4 W m−2) radiative effects, which dueto uncertainties are viewed as an order of magnitude estimate. Future workshould focus on further understanding summertime Arctic sources of AMSOA.

Zugangsstatus: Freier Zugang

Nur in Feld suchen:

Zuletzt gesuchte Begriffe: