An AeroCom intercomparison exercise on organic aerosol global modeling

Kostas Tsigaridis (1), Nikos Daskalakis (2), Maria Kanakidou (2) and the AeroCom team

1 - Center for Climate Systems Research, Columbia University, and NASA Goddard Institute for 
Space Studies, 2880 Broadway, New York, NY-10025, USA, kostas.tsigaridis@columbia.edu
2 - Environmental Chemical Processes Laboratory, Department of Chemistry, University of 
Crete, Heraklion, Greece

Comparisons of individual models with organic aerosol (OA) measurements have shown a 
large underestimation of the OA component by models. The formulations used by individual 
models are very different, since OA simulations have many degrees of freedom due to the 
missing knowledge on the behavior and fate of both primary OA (POA) and secondary OA 
(SOA) in the troposphere. On top of that, several assumptions need to be made and are 
translated to model tuning parameters that vary greatly between models. Trying to bridge 
the gap between models and observations, several recent model developments account for 
SOA, intermediate volatility organics, multiphase chemistry, oceanic fluxes and semi-volatile 
POA. 
The organic aerosol intercomparison AeroCom exercise aims to evaluate the actual status of 
global modeling of the OA occurrence in the global troposphere and analyze discrepancies 
between models as well as between models and observations. 31 global models participate 
in this exercise that aims to quantify the uncertainties and attribute them to major 
contributors and identify and analyze potential model systematic biases. The ensemble of 
the simulations are used to build an integrated and robust view of organic aerosol sources 
and sinks in the troposphere.
New results from the intercomparison will be presented together with a compilation of the 
final dataset of field data that is being used for the evaluation of the models results. 
Similarities and differences between models will be highlighted, in an attempt to evaluate 
and understand the model-measurements comparison. Future directions beyond the 
present study will also be advertised.