Details for Investigating organic aerosol loading in the remote marine environment

Name:Investigating organic aerosol loading in the remote marine environment

Lapina, K., C.L. Heald, D.V. Spracklen, S.R. Arnold, J.D. Allan, H Coe, G. McFiggans, S.R. Zorn, F. Drewnick, T.S. Bates, L.N. Hawkins, L.M. Russell, A. Smirnov, C. O'Dowd and A.J. Hind. Investigating organic aerosol loading in the remote marine environment, Atmos. Chem. Phys., 11, 8847–8860, 2011, doi:10.5194/acp-11-8847-2011.



Abstract: Aerosol loading in the marine environment is investigated using aerosol composition

measurements from several research ship campaigns (ICEALOT, MAP, RHaMBLe, VOCALS

and OOMPH), observations of total AOD column from satellite (MODIS) and ship-based instruments (Maritime Aerosol Network, MAN), and a global chemical transport model (GEOS-Chem). This work represents the most comprehensive evaluation of oceanic OM emission inventories to date, by employing aerosol composition measurements obtained from campaigns with wide spatial and temporal coverage. The model

underestimates AOD over the remote oceans on average by 0.02 (21 %), compared to satellite observations, but provides an unbiased simulation of ground-based Maritime Aerosol Network (MAN) observations. Comparison with cruise data demonstrates that the GEOS-Chem simulation of marine sulfate, with the mean observed values ranging between 0.22 μgm−3 and 1.34 μgm−3, is generally unbiased, however surface organic matter (OM) concentrations, with the mean observed concentrations between 0.07 μgm−3 and 0.77 μgm−3, are underestimated by a factor of 2-5 for the standard model run. Addition of a a sub-micron marine OM source of approximately 9 TgCyr−1 brings the model into agreement with the ship-based measurements, however this additional OM source does not explain the model underestimate of marine AOD. The model underestimate of marine AOD is therefore likely the result of a combination of satellite retrieval bias and a missing marine aerosol source (which exhibits a different spatial pattern than existing aerosol in the model).


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