Stratospheric composition Limb observations to improve NWP forecasts and (re)analyses

This work assesses the impact that the assimilation of ozone profiles has on meteorological fields in NWP simulations of recent weather events that were influenced by stratosphere-troposphere interactions.We use the European Centre for Medium-Range Weather Forecasts (ECMWF) IFS model with CAMS configurations, focusing on Northern Hemisphere winters within the period 2020-2023. We investigate the impact of Microwave Limb Sounder (MLS) ozone profiles, as MLS on the Aura satellite has been providing essential observations of ozone for the stratosphere and the upper troposphere-lower stratosphere (UTLS) regions.Chemistry-dynamics interactions in these regions are key for winter weather and climate patterns, and for the coupling between troposphere and stratosphere. Our work highlights the capacity of MLS O3 to enhance weather forecasting and shows the need for alternatives once MLS is decommissioned.Our study also explores alternatives to be used after MLS data will stop being available. And it shows the need for future observation platforms similar to the ESA-CAIRT EE11 candidate instrument, to provide atmospheric composition measurements that would enable better representation of stratospheric and UTLS processes and enhance stratosphere-troposphere coupling in weather forecast systems and reanalyses.