This cluster of papers focuses on the study of stratospheric chemistry, with a particular emphasis on the impacts of ozone depletion, changes in stratospheric water vapor, and the influence of the Brewer-Dobson circulation on climate. It also covers the role of remote sensing instruments and chemical transport models in understanding atmospheric composition and climate impact. The cluster highlights the significance of the Montreal Protocol in protecting the ozone layer and addresses the influence of solar cycle variations on stratospheric chemistry.