Stratospheric modelling and assimilation

Accurate representation of the stratosphere in NWP models is important for accurate analysis/reanalysis products. It is also important for extended-range and seasonal forecasting because stratospheric variability can influence tropospheric weather patterns on these timescales. This paper reviews the current status and recent modelling and assimilation advances with regards to the stratosphere at ECMWF. The future evolution of ECMWF's Earth System model and assimilation are outlined with a particular focus on the upper atmosphere. Examples are also shown of stratosphere-troposphere coupling for extended-range timescales, while discussing selected processes and their simulation that could improve this aspect of longer-range predictive skill.