Using the Després and Lagoutière (1999) antidiffusive transport scheme: A promising and novel method against excessive vertical diffusion in chemistry-Transport models

The potential of the antidiffusive transport scheme proposed by Després and Lagoutière (1999) for resolving vertical transport in chemistry-Transport models is inves tigated in an idealized framework with very encouraging results. We show that, compared to classical higher-order schemes, the Després and Lagoutière (1999) scheme re duces numerical diffusion and improves accuracy in ideal ized cases that are typical of atmospheric transport of trac ers in chemistry-Transport models. The increase in accu racy and the reduction in diffusion are substantial when, and only when, vertical resolution is insufficient to properly re solve vertical gradients, which is very frequent in chemistry transport models. Therefore, we think that this scheme is an extremely promising solution for reducing numerical diffu sion in chemistry-Transport models.