I presented a poster at the 2010 American Geophysical Union General Assembly on H2 as a “mesotracer.” A rare glimpse into the chemical and dynamical evolution of the Arctic polar vortex is provided by a suite of in situ balloonborne measurements. A set of mesospheric tracers observed in the late vortex validate theoretical mesospheric chemical profiles, which is especially valuable for the case of mesospheric H2. Early vortex mesospheric profiles are constructed to explain mixing in tracer-tracer space. Expanding a model to incorporate three mesotracers, H2, CO, and SF6, instead of only one, will increase our ability to constrain estimates of the amount of mesospheric air that descended to stratospheric altitudes…