Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation

We synthesised observations of total particle number (CN) concentration from 36 sites around the world. We found that annual mean CN concentrations are typically 300–2000 cm−3 in the marine boundary layer and free troposphere (FT) and 1000–10 000 cm−3 in the continental boundary layer (BL). Many sites exhibit pronounced seasonality with summer time concentrations a factor of 2–10 greater than wintertime concentrations. We used these CN observations to evaluate primary and secondary sources of particle number in a global aerosol microphysics model. We found that emissions of primary particles can reasonably reproduce the spatial pattern of observed CN concentration (R2=0.46) but fail to explain the observed seasonal cycle (R2=0.1). The modeled CN concentration in the FT was biased low (normalised mean bias, NMB=−88%) unless a secondary source of particles was included, for example from binary homogeneous nucleation of sulfuric acid and water (NMB=−25%). Simulated CN concentrations in the continental BL were also biased low (NMB=−74%) unless the number emission of anthropogenic primary particles was increased or a mechanism that results in particle formation in the BL was included. We ran a number of simulations where we included an empirical BL nucleation mechanism either using the activation-type mechanism (nucleation rate, J, proportional to gas-phase sulfuric acid concentration to the power one) or kinetic-type mechanism (J proportional to sulfuric acid to the power two) with a range of nucleation coefficients. We found that the seasonal CN cycle observed at continental BL sites was better simulated by BL particle formation (R2=0.3) than by increasing the number emission from primary anthropogenic sources (R2=0.18). The nucleation constants that resulted in best overall match between model and observed CN concentrations were consistent with values derived in previous studies from detailed case studies at individual sites. In our model, kinetic and activation-type nucleation parameterizations gave similar agreement with observed monthly mean CN concentrations.

Schlagwörter

Fachgebiet (DDC)

550 - Geowissenschaften

Projekt

Veranstaltung

Startdatum der Ausstellung

Enddatum der Ausstellung

Startdatum der Konferenz

Enddatum der Konferenz

Datum der letzten Prüfung

ISBN

ISSN

1680-7324
1680-7316

Sprache

Englisch

Während FHNW Zugehörigkeit erstellt

Nein

Zukunftsfelder FHNW

Publikationsstatus

Veröffentlicht

Begutachtung

Peer-Review der ganzen Publikation

Open Access-Status

Gold

Lizenz

Zitation

SPRACKLEN, Dominick V., Kenneth S. CARSLAW, Joonas MERIKANTO, Graham W. MANN, Carly L. REDDINGTON, S. PICKERING, John A. OGREN, Elisabeth ANDREWS, Urs BALTENSPERGER, Ernest WEINGARTNER, Michael BOY, Markku KULMALA, Lauri LAAKSO, Heikki LIHAVAINEN, Niku KIVEKÄS, Mika KOMPPULA, Ninolaos MIHALOPOULOS, Giorgos KOUVARAKIS, Stephen G. JENNINGS, Collin D. O’DOWD, Wolfram BIRMILI, Alfred WIEDENSOHLER, Rolf WELLER, John GRAS, Paolo LAJ, Karine SELLEGRI, Boris BONN, Radovan KREJCI, Ari LAAKSONEN, Amar HAMED, Andreas MINIKIN, Roy Michael HARRISON, Robert TALBOT und Junying SUN, 2010. Explaining global surface aerosol number concentrations in terms of primary emissions and particle formation. Atmospheric Chemistry and Physics. 26 Mai 2010. Bd. 10, Nr. 10, S. 4775–4793. DOI 10.5194/acp-10-4775-2010. Verfügbar unter: https://doi.org/10.26041/fhnw-9671

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