Thermodynamic and dynamic modeling of atmospheric aerosols

Citation

Meng, Zhaoyue (1997) Thermodynamic and dynamic modeling of atmospheric aerosols. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/0jjb-5n70. https://resolver.caltech.edu/CaltechETD:etd-01162008-085509

Abstract

NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. This dissertation investigates thermodynamic and dynamic modeling of urban and regional atmospheric aerosols. A rigorous and efficient aerosol thermodynamic model, SCAPE2, is developed. The model considers the inorganic aerosol system of sulfate, nitrate, ammonium, chloride, sodium, potassium, calcium, magnesium, carbonate, and water. SCAPE2 can be used to predict either the equilibrium gas/aerosol partition of volatile inorganic species or the particle surface vapor concentrations if applied to the aerosol phase only. It has also the option of predicting the equilibrium or metastable aerosol water content. A three-dimensional, size- and chemically-resolved aerosol dynamic model is developed by incorporating the aerosol thermodynamic model, SCAPE2, into an urban airshed model (CIT model). The model includes advection, turbulent diffusion, condensation/evaporation, nucleation, emissions, and dry deposition. Gas-to-particle conversion is represented by dynamic mass transfer between the gas and aerosol phases. The model employs an absorption approach in dynamically modeling production of secondary organic aerosols. A calculation method for dry deposition of aerosol particles is proposed. The aerosol model is applied to simulate gas and aerosol behavior in the 27-29 August episode in the 1987 Southern California Air Quality Study (SCAQS). Simulation results are compared systematically against SCAQS measurements, and general good agreement is observed. The assumption that volatile inorganic species such as [...] are at instantaneous, local equilibrium is examined and it is found that, in many instances, gas/aerosol mass transfer limits the rate of gas-to-particle conversion.

Thesis Files