We invite contributions exploiting dynamical and chemical models of the stratosphere (e.g. CTMs and CCMs) in conjunction with observations. New observational platforms and longer instrumental records are challenging modellers to confront numerical simulations more quantitatively with the "real world". Questions arising are: Which observations are most useful? Which derived diagnostics are required and how do they relate to physical processes? What statistical tools are most appropriate? Which metrics allow quantitative comparisons between models and observations? Is it possible to combine different measures or metrics? This session tries to encourage a broad cross-section of presentations relating to the questions above, fostering knowledge transfer and informed discussion in the field of stratospheric dynamics and chemistry.