High Resolution Observations of Hydroxyl Radical (OH) and Oxygen (O2) Emissions in the Terrestrial Nightglow

Sri International, Menlo Park CA

Investigators

Abstract

The PI proposes to carry out analyses on a broad range of hydroxyl radical (OH) Meinel bands in the nightglow throughout the 500-1100 nm spectral region. Included will be 15 different OH bands, with upper levels in the v = 3-9 range and with multiple examples of common emitting levels. The data to be used come from astronomical sky spectra obtained at the W. M. Keck Observatory on Mauna Kea. The data will be carefully calibrated against standard star spectra, so that true relative intensities can be compared over the entire spectral range. This procedure will make it possible to determine which of the current transition probability determinations in use in the aeronomic community is the more valid, and to propose an empirical correction if none are deemed adequate. The OH Meinel fluorescence is widely used to monitor nightside mesospheric conditions, and the extensive historical record of Meinel band observations provides a unique data set to monitor global change in a region of the atmosphere where change may be the most dramatic.