Auroral nitric oxide concentration and infrared emission

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Abstract
Since 1972, the Air Force Geophysics Laboratory has launched a series of rockets to study emission in the 5.3‐µm and 2.7‐µm infrared bands of nitric oxide at high altitudes. The instrumentation varied from one probe to another; infrared fixed band radiometers and CVF spectrometers, narrow band photometers and instrumentation to measure the incident energy spectrum were each included on various occasions. Optical photometric data were also obtained with ground‐based instruments. We have used the available data to model the time history and chemistry of the auroral deposition, and have concluded that (1) the NO density is significantly enhanced over mid‐latitude values, (2) the measured NO emission in the fundamental band is due to resonance excitation by warm earth radiation, collisional excitation, principally with atomic oxygen, and chemiluminescence from N(²D) + O2 → NO‡ + O, and (3) the overtone band emission is due to chemiluminescence. We have also derived the NO density and the chemiluminescence efficiency. Furthermore, we believe we have a new technique for in situ and remote measurements of NO density both day and night.