Using an antidiffusive transport scheme in the vertical direction: a promising novelty for chemistry-transport models

Abstract. The potential interest of the antidiffusive transport scheme proposed by Després et Lagoutière (1999) for resolving vertical transport in chemistry-transport models is investigated in an idealized framework with very encouraging results. We show that, compared to classical higher-order schemes, the Després et Lagoutière (1999) scheme reduces numerical diffusion and improves accuracy in idealized cases that are typical of atmospheric transport of tracers in chemistry-transport models. Increased accuracy and reduced diffusion is spectacular when, and only when vertical resolution is insufficient to properly resolve vertical gradients, which is very frequent in chemistry-transport models. Therefore, we think that this scheme is an extremely promising solution for reducing numerical diffusion in chemistry-transport models.