Chemistry of Planetary Atmospheres

Swirling storms of Saturn

I am planetary scientist that studies physical and chemical processes in the atmospheres of Jupiter, Saturn, Uranus, Neptune, extrasolar giant planets, and brown dwarfs. This work is done by constructing thermochemical and photochemical kinetics and diffusion models in order to understand the reaction behavior, transport properties, and observational effects of key atmospheric constituents. The goal of my research is to interpret the underlying chemistry for spectroscopic observations of planetary atmospheres, and to provide clues about the formation and evolution of planetary systems.

Current research projects include:
&bull Modeling coupled phosphine and ammonia photochemistry in Jupiter's upper troposphere and lower stratosphere
&bull Estimating the abundance of water in the deep atmosphere of Jupiter and the other giant planets
&bull Modeling thermochemical and photochemical processes in the upper atmospheres brown dwarfs and close-in extrasolar planets

The application of physical-chemical principles and methods has long been useful for explaining and interpreting observations of the giant planets in our own Solar System. The low densities of Jupiter and Saturn, along with evidence for saturated hydrogen compounds in their spectra (e.g., CH4, NH3) led to the early recognition that these giant planets consist mostly of hydrogen and have bulk compositions roughly similar to that of the Sun (e.g., Menzel 1930; Wildt 1934) a situation not altogether different from that of our current knowledge of extrasolar giant planets! Indeed, as the number of discovered exoplanets continues its dramatic rise (see The Extrasolar Planets Encyclopaedia), information about the chemistry of these objects remains mostly confined to what can be learned from their densities (if available) and orbits (Lodders 2010). Chemical models are therefore essential for interpreting and guiding observations of exoplanet atmospheres. Likewise, the increasing availability and quality of spectral observations of transiting exoplanets (including the detection of molecules such as CO, CO2, CH4, and H2O) provide constraints for improvements in the chemical models. As is the case for Jupiter and Saturn, improved characterization of the bulk composition and atmospheric chemistry of extrasolar giant planets (EGPs) is expected to yield clues to their formation and evolutionary history.

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