The mission of the Atmospheric Science Branch (Code SGG) is to advance the scientific knowledge and understanding of the processes that determine the behavior of the atmosphere on earth. We conduct scientific research on important environmental and climatic issues in stratospheric chemistry and ozone depletion, climatic changes due to clouds, aerosols, and greenhouse gases, stratosphere-troposphere exchange, and perturbations in the chemical composition of the troposphere. We develop and deploy highly sensitive, state-of-the-art instruments to ground sites and on a variety of platforms including aircraft, balloons, unmanned aerial systems (UAS), and ship to make observations. We develop unique models of clouds, chemistry, dynamics, and radiative transfer processes to understand and elucidate controlling mechanisms. We perform laboratory experiments to advance and understand the detailed dynamic chemical interactions in the stratosphere.