Fundamental Modeling of the Physical State of Atmospheric Particles and Application to 3D Air Quality ModelsEPA Grant Number: X832342
Title: Fundamental Modeling of the Physical State of Atmospheric Particles and Application to 3D Air Quality Models
Investigators: He, J. W. , Nenes, Athanasios , Morgan, J. , Seinfeld, John
Institution: University of Houston , California Institute of Technology , Georgia Institute of Technology
EPA Project Officer: Chung, Serena
Project Period: April 1, 2005 through March 31, 2007 (Extended to March 31, 2008)
RFA: Targeted Research Grant (2005) RFA Text | Recipients Lists
Research Category: Targeted Research
Our focus in this project is primarily on predicting aerosol phase behavior because of its important effects on the physical, chemical, and optical properties of the atmospheric particles. The intended research is in the area of mathematical modeling and computation of phase equilibria and phase transitions in atmospheric particles containing both inorganic and organic compounds. The proposed research activities will be carried out by an inter-institutional team of scientists from California Institute of Technology (J. Seinfeld), Georgia Institute of Technology (A. Nenes), and the University of Houston (J.W. He and J. Morgan) with the University of Houston as the leading institution.
The fundamental modeling research agenda will center on the following three topics:
- To develop a comprehensive mathematical model for mixed inorganic-organic atmospheric aerosols that is capable of predicting effectively liquid-liquid and liquid-solid equilibria, phase stability and separation, as well as gas/particle partitioning of semi-volatile compounds to multi-phase aerosol particles.
- To develop a multicomponent multi-physics aerosol dynamics model for micro-physically consistent treatment of deliquescence / efflorescence hysteresis, solid to solid phase transitions, and acidity transitions.
- To develop a transient kinetic model for atmospheric particles containing water-insoluble components such as mineral dusts that is capable of simulating crystallizations induced by heterogeneous nucleation.
For the wide dissemination of the models to be developed in this project, open source modular development techniques will be used. The resulting code, e.g., UHAERO module 1 (inorganic thermo), module 2 (inorganic + organic thermo) and module 3 (dynamic), will be:
- Benchmarked against thermodynamic and dynamic models currently in use by the modeling community to assess the computational performance,
- Validated against extensive laboratory data to assess the accuracy of physical predictions,
- Well-documented, user-friendly, and compatible for insertion into popular regional and global air quality models.
In addition, careful attention will be given to the performance of the resulting new models in conjunction with chemical transport models. To assess the ability of 3D air quality models with our proposed rigorous models in the prediction of the effects of the physical state of tropospheric particles on gas/particle partitioning and on global aerosol direct radiative forcing, we will:
- Incorporate our inorganic model into the U.S. EPA Models3/CMAQ model and evaluate the model performance with that of ISORROPIA by comparing the predicted partitioning of total nitrate and total ammonia between gas and aerosol phases with that of observations.
- Incorporate our inorganic model into the Harvard GEOS-CHEM model to take full account of the deliquescence / efflorescence hysteresis effect of the relative humidity history in an air parcel on the the phase transition and multistage growth of aerosols, and evaluate the model performance with that of ISORROPIA in the prediction of the effect of aqueous versus crystalline sulfate-nitrate-ammonium tropospheric particles on global aerosol direct radiative forcing.