Investigating organic aerosol loading in the remote marine environment 1Dept. of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
01 Sep 2011
2University of Leeds, Leeds, UK
3The University of Manchester, Manchester, UK
4Max Planck Institute for Chemistry, Mainz, Germany
5Pacific Marine Environmental Laboratory, NOAA, Seattle, WA, USA
6Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA, USA
7NASA/Goddard Space Flight Center, Greenbelt, MD, USA
8School of Physics and Centre for Climate and Air Pollution Studies, National University of Ireland Galway, Galway, Ireland
9Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, ME, USA
*now at: Harvard University, Cambridge, MA, USA
Received: 05 Mar 2011 – Published in Atmos. Chem. Phys. Discuss.: 08 Apr 2011Abstract. 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 ocean 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 μg m−3 and 1.34 μg m−3, is generally unbiased,
however surface organic
matter (OM) concentrations, with the mean observed concentrations
between 0.07 μg m−3 and 0.77 μg m−3, are
underestimated by a factor of 2–5 for the standard model
run. Addition of a sub-micron marine OM source of approximately
9 TgC yr−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).
Revised: 16 Jul 2011 – Accepted: 12 Aug 2011 – Published: 01 Sep 2011
Citation: Lapina, K., Heald, C. L., Spracklen, D. V., Arnold, S. R., Allan, J. D., Coe, H., McFiggans, G., Zorn, S. R., Drewnick, F., Bates, T. S., Hawkins, L. N., Russell, L. M., Smirnov, A., O'Dowd, C. D., and Hind, A. J.: Investigating organic aerosol loading in the remote marine environment, Atmos. Chem. Phys., 11, 8847-8860, doi:10.5194/acp-11-8847-2011, 2011.