Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2017-60
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
27 Feb 2017
Review status
A revision of this discussion paper was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Impact of North America on the aerosol composition in the North Atlantic free troposphere
M. Isabel García1,2, Sergio Rodríguez1, and Andrés Alastuey3 1Izaña Atmospheric Research Centre, AEMET, Associated Unit to CSIC "Studies on Atmospheric Pollution", Santa Cruz de Tenerife, 38001, Spain
2Department of Chemistry (T.U. Analytical Chemistry), Faculty of Science, University of La Laguna, La Laguna, 38206, Spain
3Institute of Environmental Assessment and Water Research, CSIC, Barcelona, 08034, Spain
Abstract. In the AEROATLAN project we study the composition of aerosols collected over ~ 5 years at Izaña Observatory (located at ~ 2400 m a.s.l. in Tenerife, the Canary Islands) under the prevailing westerly airflows typical of the North Atlantic free troposphere at subtropical and mid-latitudes. Mass concentrations of sub10-µm aerosols (PM10) carried by westerly winds to Izaña, after transatlantic transport, are typically within the range 1.2 and 4.2 µg m−3 (20th and 80th percentiles). The main contributors to background levels of aerosols (PM10 within the 1st–50th percentiles = 0.15–2.54 µg m−3) are North American dust (53 %), non-sea-salt-SO4= (14 %) and organic matter (18 %). High PM10 events (75th–95th percentiles ≈ 4.0–9.0 µg m−3) and are prompted by dust (56 %), organic matter (24 %) and nss-SO4= (9 %). These aerosol components experience a seasonal evolution explained by (i) their spatial distribution in North America and (ii) the seasonal shift of the North American outflow, which migrates from low latitudes in winter (~ 32º N, January–March) to high latitudes in summer (~ 52º N, August–September). The westerlies carry maximum loads of nss-sulphate, ammonium and organic matter in spring (March–May), of North American dust from mid-winter to mid-spring (February–May) and of elemental carbon in summer (August–September). Our results suggest that a significant fraction of organic aerosols may be linked to sources other than combustion (e.g. biogenic); further studies are necessary for this topic. The present study evidences how long-term evolution of the aerosol composition in the North Atlantic free troposphere will be influenced by air quality policies and the use of soils (potential dust emitter) in North America.

Citation: García, M. I., Rodríguez, S., and Alastuey, A.: Impact of North America on the aerosol composition in the North Atlantic free troposphere, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-60, in review, 2017.
M. Isabel García et al.
M. Isabel García et al.

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