Chapter 4.9 Modelling of the July 10 STERAO storm with the RAMS model: Chemical species redistribution including gas phase and aqueous phase chemistry

The meso-scale RAMS model has been applied to the July 10, 1996, STERAO storm observed in Colorado using an idealized horizontally homogeneous sounding with warm bubble initiation. This simulation was done in the framework of the WMO cloud modeling workshop intercomparison on chemistry transport in deep convection led by Mary Barth. The RAMS model coupled with gas and aqueous chemistry simulates CO and O₃ mixing ratios similar to observations and other models. The anvil area, mass flux, CO flux and NO_x flux simulated by the RAMS-chemistry model are found to be within 35% of the values deduced from observations. We further examine the simple parameterization of NO production from lightning used in the RAMS simulations, which lead to a good agreement between computed and observed NO_x fluxes. Moreover, because the RAMS model allows using either single or double moment microphysical schemes, the impact of the microphysical scheme is examined in terms of chemical species redistribution by the storm. Finally, the effect of gas phase versus aqueous phase chemistry on chemical species redistribution by the storm is also studied.