Measured profiles of the vertical distributions of the volume emission rates of the O H infrared airglow are presented. These measurements by various investigators constitute a total of 34 rocket flights and were obtained at both mid and high latitudes, at various solar depression angles, and at various times of the year using rockets which flew into the middle atmosphere. Some 55 profiles are summarized. Quantitative altitude comparisons are made at various locations. Included in the comparisons are volume emission rate profiles at IR as well as at visible wavelengths. From all of the profiles reported, the value of the mean altitude of the peak OH volume emission rate is 87.4 km, and the mean half-power thickness is 12.4 km. However, we recommend as working numbers to be used: 86.8 2.6 km for the altitude of the peak and 8.6 i 3.1 for the thickness of the O H emission layer [taken from the selected profiles of Table 1111.* This paper was contributed to the 6th International Symposium on Solar Terrestrial Physics, held in Toulouse, France, June 30-July 5 , 1986, and will be included in part I1 of the Conference proceedings (editor: B. Hultqvist).

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Improved spectral measurements of the OH Meinel Δv = 3 night airglow emissions have revealed unexpectedly intense transitions from high rotational levels. The example selected for this communication involves the previously unreported P(N″ = 13) transitions in the OH M (7, 4) band. Under the extant conditions, the column emission rates associated with these new features exceeded by factors ∼104 those expected on the basis of the assumption of rotational‐kinetic equilibrium for the v′ = 7 rotational manifold. We present the key observations and discuss some of the implications.

Global measurements of the hydroxyl mesospheric airglow over an extended period of time have been made possible by the NASA SABER infrared sensor aboard the TIMED satellite which has been functioning since December of 2001. The orbital mission has continued over a significant portion of a solar cycle. Experimental data from SABER for several years have exhibited equatorial enhancements of the nighttime mesospheric OH ( v = 2) airglow layer consistent with the high average diurnal solar flux. The brightening of the OH airglow typically means more H + O 3 is being reacted. At both the spring and autumn seasonal equinoxes when the equatorial solar UV irradiance mean is greatest, the peak volume emission rate (VER) of the nighttime Meinel infrared airglow typically appears to be both significantly brighter plus lower in altitude by several kilometres at low latitudes compared with midlatitude findings.

A Spectral Infrared Rocket Experiment was launched from Poker Flat, Alaska, on September 28, 1977, to measure infrared emission spectra from the earth limb atmosphere. Spectrometers measured emission spectra from 1.40 to 16.5 µm during 12 vertical scans of the limb region (tangent heights 0 to 250 km) traversing the night, terminator, and day sectors of the limb atmosphere. The spectrometers were cryogenically cooled and telescoped for out‐of‐field rejection of the more intense radiation from lower altitudes. High‐quality spectra were obtained with clearly identifiable features of CO2, O3, NO, OH, H2O, NO2, HNO3, and O2, as well as Rayleigh scattering. Spectra and tangent height emission profiles of selected species are presented and compared with theoretical emission models including those of Degges and Smith (Limb Model) and LOWTRAN 4. The salient findings are as follows: At a height of 80 km, CO2 daytime emission from fluorescence around 4.3 µm was almost 2 orders of magnitude greater than the nighttime emission. At 15 µm the CO2 radiance profiles showed little day‐night differences but exhibited an unexpected radiance plateau between 95 and 110 km. The ozone peak radiance at 9.6 µm (ν3) showed order of magnitude day‐night differences above 70 km tangent height showing a decrease in concentration of O3 during daytime due to photodissociation. The observed radiance in the 9‐ to 12‐µm wavelength region exhibited evidence of chemiluminescent emission from hot bands of O3. NO (Δυ = 1) peak radiance at 5.3 µm, due to O atom excitation, is a broad maximum at 120 km tangent height. The nighttime OH fundamental (Δυ = 1) and overtone (Δυ = 2) emissions showed extensive radiation from higher vibrational levels. The daytime 2.7‐µm fluorescent radiation was composed of emission from both H2O and CO2. Emission from NO2 at 6.15 µm (ν3) was observed at night only but was clearly identifiable amid the H2O (ν2) spectrum. Measured radiation in the 6.3‐µm vibrational band of water vapor at 60 and 70 km agrees with the Air Force Geophysics Laboratory non‐local thermodynamic equilibrium Limb Model using mixing ratios of 5 and 1.5 parts per million by volume, respectively. The radiance from O2 (a¹Δg) at 1.58 µm was observable from tangent heights of 30 to 80 km in the daytime only and shows a critical dependence upon the solar elevation angle. As expected, Rayleigh scattering was the dominant daytime source of radiation between 1 and 3 µm in the limb atmosphere for tangent heights of up to 40 km.