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GEM-AQ is a global multiscale air quality model based on the Canadian operational weather prediction model, GEM (Global Environmental Multiscale model) developed by the Meteorological Service of Canada (MSC). Currently, there are 37 advected gas phase species and 2 size-resolved aerosol types (sulphate and sea salt, 12 size bins each) totalling 61 advected chemical species. The gas phase chemistry based on the ADOM (Acid Deposition and Oxidants Model) IIb mechanism (Lurmann et al., 1986) includes 99 chemical reactions and 16 photolysis reactions. Area source emissions of several species are included as well as dry deposition and simple wet scavenging. A list of the species involved can be found here. The aerosol processes included in GEM-AQ are based on the Canadian Aerosol Module (CAM) (Gong et al., 2003). These processes include:
Other physical processes included are transport of the chemical species due to deep convection and vertical diffusion. GEM-AQ is currently being run on Linux machines, but is also capable of running on IRIX (SGI), NEC SX-6, and soon AIX (for IBM cluster). The Portland Group FORTRAN 90 compiler is required to compile the model under Linux. The model is capable of using MPICH (a portable implementation of Message Passing Interface) to run with more than one processor. References noted: Lurmann, F. W., A. C. Lloyd and R. Atkinson, A chemical mechanism for use in long-range transport/acid deposition computer modeling, J. Geophys. Res., 91, 10905-10936, 1986. Gong, S. L., et al., Canadian Aerosol Module: A size-segregated simulation of atmospheric aerosol processes for climate and air quality models, 1. Module development, J. Geophys. Res., 108(D1), 4007, 2003.
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