Six-moment representation of multiple aerosol populations in a sub-hemispheric chemical transformation model

This letter describes the first application of the Quadrature Method of Mom ents (QMOM) [McGraw, 1997] in a 3-D chemical transformation and transport m odel. The QMOM simultaneously tracks an arbitrary (even) number of moments of a particle size distribution directly in space and time without the need for explicitly representing the distribution itself. The host 3-D model, t he Global Chemistry Model driven by Observation-derived meteorological data (GChM-O), has been previously described [Benkovitz et al., 1994]. The pres ent implementation evolves the six lowest-order radial moments for each of several externally-mixed aerosol populations. From these moments we report modeled geographic distributions of several aerosol properties, including a shortwave radiative forcing obtained using the Multiple Isomomental Distri bution aerosol Surrogate (MIDAS) technique [Wright, 2000]. These results de monstrate the capabilities of these moment-based techniques to simultaneous ly represent aerosol nucleation, condensation, coagulation, dry deposition, wet removal, cloud activation, and transport processes in a large scale mo del, and to yield aerosol optical properties and radiative influence from t he modeled aerosol.