Particle resolved simulations for modeling aerosol mixing state
Work in collaboration with Matthew West, Rahul Zaveri, Richard Easter and James Barnard.
Funded by NSF award ATM 0739404
Atmospheric aerosols can be composed of a complex mix of compounds such as soluble inorganic salts and acids, insoluble crustal materials (dust), trace metals, and carbonaceous materials, which include primary and secondary organic compounds of anthropogenic and biogenic origins as well as soot formed as result of fossil fuel combustion and biomass burning.
The mixing state of atmospheric aerosol particles is of crucial importance for assessing their macroscopic impacts. However, tracking the mixing state in conventional aerosol models requires treating a multidimensional size distribution, which is computationally prohibitive. Therefore current models usually assume an internal mixture within one mode or size section. The uncertainties associated with this assumption, which artificially ages freshly emitted particles instantly, are not well quantified.
To improve upon this situation we are developing a new approach, the stochastic particle resolved model PartMC-MOSAIC, which explicitly resolves the composition of individual particles in a given population of different types of aerosol particles, and accurately tracks their evolution due to emission, dilution, condensation and coagulation. In this sense, PartMC-MOSAIC serves as a benchmark model capability to provide baseline simulations for validating modal and sectional models and for improving the current aging parameterizations.
Publications
N. Riemer, M. West, R.A. Zaveri, R.C. Easter [2009] Estimating soot aging time scales with a particle-resolved aerosol model, Journal of Aerosol Science, accepted, preprint at arXiv:0903.0029v1
N. Riemer, M. West, R.A. Zaveri, R.C. Easter [2009] Simulating the evolution of soot mixing-state with a particle-resolved aerosol model, Journal of Geophysical Research, 114, D09202, DOI: 10.1029/2008JD011073.
R. McGraw, L. Leng, W. Zhu, N. Riemer, M. West [2008] Aerosol dynamics using the quadrature method of moments: Comparing several quadrature schemes with particle-resolved simulation, Journal of Physics: Conf. Series, 125, 012020, DOI: 10.1088/1742-6596/125/1/012020. (pdf)
N. Riemer and A.S. Wexler [2005] Droplets to drops by turbulent coagulation, Journal of the Atmospheric Sciences 62, 1962-1975. (pdf)
N. Riemer, H. Vogel, B. Vogel, F. Fiedler [2003] Modeling aerosols on the mesoscale-γ: Treatment of soot aerosol and its radiative effects, Journal of Geophysical Research 108, 4601, DOI: 10.1029/2003JD003448. (pdf)