The HALO (High Altitude and LOng Range Research Aircraft) mission WISE (Wave-driven ISentropic Exchange) aims at providing new scientific insight related to the following questions: What is the impact of wave-driven large scale eddy mixing on the composition of the mid- to high-latitude LMS? What is the role of the Asian Monsoon in moistening the extra-tropical UTLS in summer? What are typical time scales for mixing and how are these related to the underlying dynamical processes and source regions? Does the TIL affect transport and mixing into the lower stratosphere and within the lower stratosphere? Which factors determine the formation of the TIL and how do these in turn affect transport? What is the link between Rossby wave breaking events and associated transport of water vapor and cirrus formation at mid latitudes?