Predoctoral Projects, 2014

Project Title: Planetary Atmospheres Spectral Catalog

Project Advisor: Dr. Laurence S. Rothman

Background: The HITRAN molecular spectroscopic database is maintained and developed at the Smithsonian Astrophysical Observatory. This database consists primarily of parameters of molecular absorption transitions that are used for various transmission and radiance codes for simulating spectra from the microwave region through the UV. The emphasis to date has been for the terrestrial atmosphere. Thus the molecules and their significant isotopologues have been related to those that are observed on Earth. In addition, the Lorentzian halfwidths in the database have been those caused by collisions with air or self-broadening.

Scientific Questions: This project has the goal of extending the application of the HITRAN database to planetary atmospheres besides the Earth. What are the molecular transitions in pure rotation (mostly microwave) and vibration-rotation (mostly the infrared and visible) that need to be added to HITRAN to allow future spectroscopic remote sensing experiments to characterize planetary atmospheres? What are the line shape parameters for these atmospheres?

Scientific Methodology: Calculated and/or measured halfwidths of other foreign gas broadeners (such as N2, H2, He, A, CO2, H2O) from the literature need to be assembled and evaluated. Algorithms that represent the halfwidths as a function of vibrational and rotational quanta should be developed, as well as temperature dependences of these quantities. Linelists (transition wavenumbers, intensities, lower-state energies) of molecules such as SO, CS2, H3+ etc. need to be calculated and compiled. Partition sums over a wide range of temperatures for any species being added to HITRAN need to be derived.

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Clay Fellow Warren Brown