Vibrationally Excited Nitric Oxide in the Upper Atmosphere

Abstract

Vibrational levels of the ground states ((2)pi (1/2), 3/2) of nitric oxide are populated by transfer of vibrational quanta in collisions with molecular oxygen and nitrogen; by atom exchange with atomic oxygen; by absorption of infrared radiation from the earth's surface, the lower atmosphere, and the sun; by fluorescent decay of the beta-, gamma-, and delta-band systems following resonance absorption of solar ultraviolet radiation; by electron impact excitation; and during chemical formation. These excitation mechanisms are balanced by collisional deexcitation and by radiation in the infrared vibration rotation bands. The relative importance of each of these processes is assessed for quiescent day and night conditions and for aurorae. In the absence of collisional interactions, absorption of terrestrial infrared radiation maintains a vibrational temperature of between 220 K and 270 K near the mesopause.

Infrared emission from NO (Δυ=1) in an aurora: Spectral analysis and kinetic interpretation of HIRIS measurements

“…For representative profiles of [O] and T [Jacchia, 1977], the anticipated column emission rate in photons cm -2 s -' due to (R 1) is (2.4 x 10 -5) [NO]x, (1.7 x 10 -n) [NO]x, and (1.0 x 10 -3) [NO] x at altitudes of 100 km, 110 km, and 120 Table 2). By comparison, the contribution of radiative excitation via (R4) is estimated [Degges, 1971] Figure 7; the results qualitatively exhibit the predicted trend with auroral intensity, and the least squares line through the data has a negative slope that is significantly different from zero at the 95% confidence level.…”

“…It is now generally accepted [Degges, 1971] (R1) and (R4) simply drive the NO vibrational temperature toward the equilibrium value. Reactions (R2) and (R3) are the major sources of total NO in the daytime [Strobel et al, 1976]; furthermore, recent laboratory investigations have shown that (R2) produces a modest degree of NO vibrational excitation [Hushfar et al, 1971, while (R3) gives extensive initial excitation of the product NO [Kennealy et al, 1978].…”

Auroral nitric oxide concentration and infrared emission

“…On the basis of the preceding discussion, we concluded that the 5.3-/am emission was not determined by the instantaneous or recent energy deposition levels. Previously, Degges [1971] Kockarts [1980] has suggested that NO emission at 5.3-/am may be a significant mechanism for cooling the auroral region above 120 km. Degges [1971] has shown that for an NO integrated column density of 1.5 x 1015 cm -2, optical thickness in even the strongest line may be neglected.…”

“…Nitric oxide is one of the principal short wavelength infrared emitters in the upper atmosphere, and this emission and the processes that produce it have been the subject of a considerable body of research in recent years [Degges, 1971;Hyman et al, 1976;Swider, 1976;Gerard and Barth, 1977; Baker et al, 1977a;Hurd et al, 1977;Swider and Narcisi, 1977;Cravens and Stewart, 1978;Swider, 1978;Thomas, 1978;Trinks et al, 1978;Massie, 1980;Wittet al, 1981;Rawlins et al, 1981]. The experimental studies have demonstrated that the NO emission varies considerably with latitude and auroral activity, with the strongest emission in polar regions during times of strong and extended magnetic storms.…”

Excitation of vibrational emission bands in aurora and airglow

“…Since then, much attention has been paid to theoretical examination of thermospheric emissions in vibrational molecular bands. For instance, Degges (19) analyzed excitation mechanisms of the NO 5.3-pm emission in the undisturbed thermosphere. James and Kumer (20,21) calculated vibrational temperatures of NZ and of the asymmetric mode v3 of COZ in the quiet mesosphere and lower thermosphere as well as the emission intensity of the 4.3-pm band of COZ, taking into account reabsorption of the radiation.…”