Midlatitude observations of the night airglow from 3000 to 9200 /• were made with a ground-based panchromatic intensified charge coupled device (ICCD) spectrograph over a period of 4 months. Intensities of the Herzberg I, Chamberlain, Herzberg II, and atmospheric systems of molecular oxygen, the Meinel bands of hydroxyl, and the atomic oxygen 5577-/• emission were measured. Synthetic spectra and integration were used to determine the emission intensities of these features. The results were used to constrain a middle atmospheric model. Output from this model showed that quenching processes severely depopulate the states to the extent that electronic, vibrational, and rotational populations do not retain the signatures of the excitation reactions or the radiative depopulation processes. The observed coupling between the levels of the O2(A3Eu +. A'3Au, clE•) states and the observed vibrational distribution of the OH(X2II) levels also supported this heavy quenching hypothesis. The average intensities for a 6.5-hour integration period on March 16, 1991, of the 02 Herzberg I, Chamberlain, Herzberg II, and atmospheric (0-1) emissions were 350_+30 R, 120_+15 R, <120 R, 350_+20 R, respectively; the OH Meinel (9-4), (8-3), (7-2), (7-3), (6-2), (5-1), and (4-0) intensities were 450_+50 R 450_+20 R, 90_+20 R, 1620_+200 R, 970_+50 R, 680_+150 R, 190_+20 R; the O I(5577•) intensity was 320_+10 R; the average OH Meinel (6-2) temperature was 200 ø K. INTRODUCTION Mesospheric and lower thermospheric night airglow emissions occur at altitudes of 80 to 100 km in the atmosphere. These emissions are influenced strongly by the processes which occurred when the atmosphere was sunlit. Dayglow conditions relax very quickly after sunset [Rodrigo et al., 1986], but the active conditions during the day determine the vertical distribution of the interacting species in the night. The emissions from the night sky and their relationship to chemical processes which produce them have been studied for many years. Weak intensity was a limiting factor in those studies. The spectrum, such as Broadfoot and Kendall [1968] produced, took nearly 54 hours to record through many nights with a very "fast" instrument at that time. The extensive observing time required for useful measurements precluded a serious attack on the physical processes responsible for the emission because exposure times were longer than the time frame of dynamical effects. Studies using spectrometerphotometer combinations, such as Stegman and Murtagh [1991], have made progress. Because of the utilization of modern detectors, the instrumentation used in this study demonstrated that a spectrum similar to that of Broadfoot and Kendall [1968] could be taken in ~1 hour. The complete (3000-9200 ]k) spectrum can be recorded simultaneously. This allows the measurements to be made of the airglow spectrum at the same time from the same gas column. Thus the relationship of the system intensities, vibrational, and rotational distributions can be studied as a function of time. Observational time ...
