Articles | Volume 8, issue 3
Development and technical paper
20 Mar 2015
Development and technical paper |  | 20 Mar 2015

Evaluation of the global aerosol microphysical ModelE2-TOMAS model against satellite and ground-based observations

Y. H. Lee, P. J. Adams, and D. T. Shindell

Abstract. The TwO-Moment Aerosol Sectional (TOMAS) microphysics model has been integrated into the state-of-the-art general circulation model, GISS ModelE2. This paper provides a detailed description of the ModelE2-TOMAS model and evaluates the model against various observations including aerosol precursor gas concentrations, aerosol mass and number concentrations, and aerosol optical depths. Additionally, global budgets in ModelE2-TOMAS are compared with those of other global aerosol models, and the ModelE2-TOMAS model is compared to the default aerosol model in ModelE2, which is a one-moment aerosol (OMA) model (i.e. no aerosol microphysics). Overall, the ModelE2-TOMAS predictions are within the range of other global aerosol model predictions, and the model has a reasonable agreement (mostly within a factor of 2) with observations of sulfur species and other aerosol components as well as aerosol optical depth. However, ModelE2-TOMAS (as well as ModelE2-OMA) cannot capture the observed vertical distribution of sulfur dioxide over the Pacific Ocean, possibly due to overly strong convective transport and overpredicted precipitation. The ModelE2-TOMAS model simulates observed aerosol number concentrations and cloud condensation nuclei concentrations roughly within a factor of 2. Anthropogenic aerosol burdens in ModelE2-OMA differ from ModelE2-TOMAS by a few percent to a factor of 2 regionally, mainly due to differences in aerosol processes including deposition, cloud processing, and emission parameterizations. We observed larger differences for naturally emitted aerosols such as sea salt and mineral dust, as those emission rates are quite different due to different upper size cutoff assumptions.

Short summary
We have implemented the TwO-Moment Aerosol Sectional (TOMAS) microphysics model in NASA GISS ModelE2, called “ModelE2-TOMAS”. We compared global budgets of ModelE2-TOMAS to other global aerosol models and evaluated the model with various observations such as aerosol precursor gas, aerosol mass, number concentrations, and aerosol optical depth. We found that ModelE2-TOMAS agrees with observations reasonably and that its predictions are within the range of other global aerosol model predictions.