The new emerging generation of seamless Earth system models (ESMs) needs to be developed in ways that allow accurate performance on timescales from weather to climate, including seasonal and sub-seasonal timescales. This requires slow-evolving processes that influence the troposphere, like stratospheric processes, to be realistically included. The stratosphere is rising as one of the keys to improve tropospheric weather and climate predictions, and modelling realistic feedbacks between stratospheric composition, radiation, temperature and dynamics is essential to correctly simulate the behaviour of the stratosphere and its links with surface weather and climate.
In this talk I will present examples of major interactions between atmospheric chemistry and physics relevant for weather and climate predictions. I will focus on the role played by the stratospheric ozone layer, and by large volcanic eruptions reaching the stratosphere. I will discuss results obtained with an alternative ozone model that demonstrate the role stratospheric ozone plays to improve weather forecasts on several timescales, as shown by Monge-Sanz et al. (2022) with ECMWF model runs.
Despite the relevance of stratospheric composition, full-chemistry descriptions for the stratosphere are still largely reserved for coarser resolutions than operational numerical weather prediction (NWP) models require, mainly due to computational costs, and such full-chemistry descriptions are not yet affordable for multi-ensemble long-range simulations. I will discuss alternative strategies for the inclusion of chemistry-dynamics feedbacks in seamless Earth System Models.