Observational Investigation of Dynamical and Photochemical Variability in the Venus Middle Atmosphere

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The atmospheres of Venus and Earth formed in early solar system conditions that were fairly similar, but ended up very different. Venus's massive carbon dioxide dominated atmosphere presents substantial observational challenges due to its expansive vertical extent and distinct regimes of thermal, chemical, and dynamical conditions. This project is an observational study of the Venus middle mesosphere (at 70-100 km altitude) and lower thermosphere (100-120 km), regions characterized by complex chlorine, oxygen, sulfur, and hydrogen photochemistry, as well as a dynamical transition from retrograde flow (opposite to the planet?s rotation) at lower altitudes to dayside-to-nightside circulation above. The Principal Investigator and collaborators will use ground-based and airborne telescopes, including the James Clerk Maxwell Telescope (JCMT), the Atacama Large Millimeter/Submillimeter Array (ALMA), and the Stratospheric Observatory for Infrared Astronomy (SOFIA) to measure the spatial and temporal distribution of temperatures, winds, and molecular species. The goals are to constrain (1) the temporal and spatial variability in chemistry and circulation, (2) the photochemistry of the mesosphere, and (3) the physics underlying the circulation and compositional gradients. The broader impact of the project derives from its contribution to understanding Earth-like planets, which are now thought to be common around stars other than the Sun; Venus provides the best opportunity to understand how an Earth-like planet can evolve to an environment very unlike that of Earth.