Simulating Hydrocarbon Distribution in the Jovian Stratosphere in a Chemistry-Transport Model

The chemical and dynamical processes in the stratosphere of Jupiter are poorly known. In this work, we constrain the meridinal transport processes using the latitudinal distributions of ethane and ethylene obtained by the Cassini spacecraft during Jupiter flyby in 2000 (Nixon et al. 2010; Zhang et al., 2012). Previous studies (Kunde et al. 2004; Liang et al., 2005) have suggested that the horizontal transport timescale between 1-10 mbar should fall within 1 to 300 years, i.e., the chemical lifetimes of ethylene and ethane, respectively. But the relative roles of diffusion (eddy-mixing) and advection in the horizontal transport are highly uncertain, as revealed by other tracers such as HCN and CO2 (Lellouch et al., 2006). We introduce a two-dimensional (latitude-pressure) photochemical-diffusive-advective model to simulate the distribution of hydrocarbons in the stratosphere. Analytical solutions, both in one-dimensional (pressure) and two-dimensional coordinates, are derived to gain the physical insight of the coupled chemical-transport processes, and also used for validating the numerical methods. The residual mean circulation derived from the instantaneous radiative forcing during the Cassini flyby (Zhang et al., 2012) is applied to the simulations. The effects of polar aerosol heating and possible chemical sources due to ion chemistry in the aurora regions are discussed.