Aerocenter Seminar: Jen-Ping Chen

Department of Atmospheric Sciences, National Taiwan University

The size distribution of aerosol particles has strong influence on cloud formation and radiative processes. Its evolution involves complicated physical and chemical processes. The treatment of aerosol size distribution can be approached in detailed or simplified ways, but for regional to global scale studies, parameterized schemes are still a more practical way for efficient modeling. In this study, a new bulk parameterization scheme is developed, which provides the change rate of three or more moments for each particle modes (e.g., nuclei, accumulation and coarse modes) without using simplified growth kernel as did in many advanced parameterization schemes.

This parameterization scheme is verified via multiple approaches including comparisons with analytical solutions and numerical solutions. Coagulation process is the most complicated process because of its nonlinear growth kernel and double integral form. So, particular emphasis is placed on the testing of coagulation process, using simplified and real kernels. Preliminary results show that our scheme is more accurate and computationally more efficient than the popular scheme of Binkowski and Shanker (1995). This new aerosol parameterization has been implemented into a regional mineral dust model to check its applicability in emission, advection and deposition processes, as well as a regional air quality model CMAQ to verify its general performance. Further applications of this scheme using CMAQ are demonstrated for two topics: (1) Kelvin effect on particles growth; (2) the mixture state of aerosols.