Currently the EPA's Community Model for Air Quality (CMAQ) includes several options for computing aerosols, each using somewhat different approaches. One in particular has been "frozen" by EPA and has been used in an annual run in support of visibility modeling studies being conducted by Regional Planning Organizations (RPOs). This module is based on work done by Binkowski and Roselle, 2003, utilizing a modal approach to describe aerosol size distributions and number concentrations.

Due to increasing computational power, it may become practical to run atmospheric pollutant forecasts using this module, and for that reason it has been implemented in the WRF-Chem code. WRF-Chem is an evolving state-of-science integrated on-line meteorological-chemistry model using NCAR's Eulerian mass-based dynamical core.

Tests have been conducted on a case comparing results from the new module against an earlier implementation which is based on the Modal Aerosol Dynamics Model for Europe (MADE) (Ackermann et al., 1998)incorporating secondary organic aerosols (SOA) by means of the secondary organic aerosol model (SORGAM, Schell et al., 2001). Results of the tests and insights gained will be discussed, along with plans to release the new module to the WRF community.