The Quasi-Biennial Oscillation (QBO) of zonal-mean zonal winds in the tropical stratosphere is a conspicuous feature of the Earth climate. Its influence virtually extends to the whole atmosphere. The QBO is driven by the dissipation of waves generated by deep convection in the tropics. Yet, a significant fraction of these waves have spatial scales that are not explicitly resolved in current climate models, so that the evolution of the QBO in a changing climate still remains unclear. A study by \citeA{Vincent2020} shows that recent long-duration balloon observations, combined with information on the vertical structure of the tropical atmosphere, could contribute to provide significantly improved constraints on wave parameterization in models.