We have helped develop a global three-dimensional chemical transport model called Model of Ozone and Related Chemical racers, version 2 (MOZART-2). Horowitz et al. (2003) includes a description and evaluation of MOZART-2. This model is built on the framework of the National Center for Atmospheric Research (NCAR) Model of Atmospheric Transport and Chemistry (MATCH). The animations of chemical tracer transport shown here use the standard configuration of the model, which is driven by meteorological inputs every 3 hours from the middle atmosphere version of the NCAR Community Climate Model (MACCM3). The simulations use a 20-min time step and a horizontal resolution of 2.8° latitude by 2.8°longitude with 34 vertical levels extending up to approximately 40 km. MOZART-2 includes a detailed chemistry scheme for tropospheric ozone, nitrogen oxides, and hydrocarbon chemistry, with 63 chemical species. Tracer advection is performed using a flux-form semi-Lagrangian scheme with a pressure fixer with the inclusion of subgrid-scale convective and boundary layer parameterizations. Surface emissionsinclude sources from fossil fuel combustion, biofuel and biomass burning, biogenic and soil emissions, and oceanic emissions. Parameterizations of dry and wet deposition are included. Stratospheric concentrations of several long-lived species (including ozone) are constrained by relaxation toward climatological values.
Animations are based on 1990 emissions and projected 2020 emissions. To simulate the concentration of chemical species in 2020 we used the 2001 Intergovernmental Panel on Climate Change (IPCC) B2-Message scenario to scale the spatially and temporally varying 1990 anthropogenic emissions used in MOZART-2. The IPCC developed emission scenarios following story lines. The B2 scenario family is intended to represent one where there is moderate population growth, intermediate levels of economic development, increased concern for environmental and social sustainability. Hence, it is not a “worst-case” scenario.
Both the 1990 and 2020 animations include the global distributions of total O3, CO, PAN, HNO3 and NOx. In addition, for each region (North America, Europe, East Asia, Former Soviet Union, Tropical Asia, Africa, and South America), and emission type (fossil fuel combustion and biomass burning) we have conducted “tagged” simulations. In these tagged simulations, the emissions of CO and NOx (including its oxidation species HNO3 and PAN) from one region of the world are separately identified and tracked through their chemical transformations and global transport. The distribution of tagged tracers are shown in two panels – the top panel shows, at any given location, the percentage of the chemical species that originated from the particular region as a fraction of the global total, and the bottom panel shows the actual concentration of the tracer.