Evaluating aerosol nucleation parameterizations in a global atmospheric model

Numerically efficient parameterizations based on theories of binary, ternary and ion-induced aerosol nucleation (BN, TN and IN) enable online calculations of new particle formation in high resolution atmospheric models. These parameterizations are evaluated interactively in a 3D global chemical transport model that simulates gaseous sulfuric acid, ammonia and the ion-pair production rate. The BN and IN parameterizations produce new particles only in the cold upper troposphere, with IN giving relatively lower nucleation rates due to parameterization errors. In contrast, the TN parameterization predicts new particle formation throughout the troposphere, but gives unrealistically high nucleation rates. New and revised TN theories from recent studies instead give much lower rates and indicate that TN is not likely in the lower troposphere. Nucleation parameterizations can be useful for global modeling applications, but the current schemes should be used cautiously given their large uncertainties.