CEDAR: Mesospheric Temperatures Probed by Simultaneous Measurement of OH and O2 in the Nighthglow

Sri International, Menlo Park CA

Investigators

Abstract

PI: Cosby, Philip ATM-9908767 The PI proposes to study the fundamental foundation for the extraction of mesospheric temperatures from OH Meinel band spectra. The extensive historical record of Meinel band observations provides a unique data set for monitoring global change in a region of the atmosphere where changes may be the most dramatic. Inconsistency in results from the historical record of one site to another complicate concrete conclusions from OH emission measurements. To nightglow spectrum used in this initial analysis is the sum of hundreds of individual spectra acquired by 14 groups observing stars or quasars with the HIRES echelle spectrometer on the Keck 1 telescope on Mauna Kea, Hawaii, over a period from December 1994 through May 1997. The spectrum covers the wavelength range from 573 to 893 nm, with total accumulation time in excess of 100 hours on this optically fast instrument. The PI proposes to analyze the individual spectra that comprise this highly averaged sum, characterizing the Meinel band emission together with the O2 0-1 atmospheric band emission with regard to seasons, intense and weak nights, and other pertinent sorting criteria to determine how best to relate the apparent OH rotational temperature from a specific band to the average thermal energy of the mesosphere at the altitude of the emission.