Atmos. Chem. Phys. Discuss., 6, 3465-3512, 2006
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
MALTE – Model to predict new aerosol formation in the lower troposphere
M. Boy1,2, O. Hellmuth3, H. Korhonen4, E. D. Nilsson5, D. ReVelle6, A. Turnipseed7, F. Arnold8, and M. Kulmala1
1Department of Physical Sciences, Division of Atmospheric Sciences, P.O. Box 64, 00014 University of Helsinki, Finland
2ASP/ACD, NCAR, P.O. Box 3000, 80305 Boulder, Colorado, USA
3Leibniz Institute for Tropospheric Research, Permoserstrasse 15, 04318 Leipzig, Germany
4Finnish Meteorological Institute, Air Quality Research, Sahaajankatu 20 E, FIN-00880 Helsinki, Finland
5Department of Meteorology, Stockholm University, S-106 91 Stockholm, Sweden
6Earth and Environmental Sciences, Los Alamos National Laboratory, P.O. Box 1663, MS D401, Los Alamos, NM, 87545, USA
7ACD, NCAR, P.O. Box 3000, 80305 Boulder, Colorado, USA
8Atmospheric Physics Division, Max-Planck Institute for Nuclear Physics, (MPIK), P.O. Box 103980, 69029 Heidelberg, Germany

Abstract. The manuscript presents a detailed description of the meteorological and chemical code of Malte – a model to predict new aerosol formation in the lower troposphere. The aerosol dynamics are achieved by the new developed UHMA (University of Helsinki Multicomponent Aerosol Model) code with kinetic limited nucleation as responsible mechanism to form new clusters. First results indicate that the model is able to predict the on- and offset of new particle formation as well as the total aerosol number concentrations that were in good agreement with the observations. Further, comparison of predicted and measured H2SO4 concentrations showed a satisfactory agreement. The simulation results indicated that at a certain transitional particle diameter (2–9 nm), organic molecules can begin to contribute significantly to the growth rate compared to sulphuric acid. At even larger particle sizes, organic molecules can dominate the growth rate on days with significant monoterpene concentrations. The intraday vertical evolution of newly formed clusters and particles in two different size ranges resulted in two maxima at the ground and the top of the mixed layer with higher concentrations for the detectable particles above 3 nm below in contrast to the predicted cluster concentrations.

Citation: Boy, M., Hellmuth, O., Korhonen, H., Nilsson, E. D., ReVelle, D., Turnipseed, A., Arnold, F., and Kulmala, M.: MALTE – Model to predict new aerosol formation in the lower troposphere, Atmos. Chem. Phys. Discuss., 6, 3465-3512, doi:10.5194/acpd-6-3465-2006, 2006.
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