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Journal of Geophysical Research



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A Paiute-Tomahawk sounding rocket containing a 1.5- to 5.3-•m cryogenically cooled spectrometer was flown into a very bright (IBC III +) auroral breakup from Poker Flat, Alaska. The main emission features at 2.8, 4.3, and 5.3 um were all found to be enhanced owing to the larg•e energy input to the atmosphere associated with the aurora. The most prominent enhancement occurred in the 4.3-Urn feature which is identified as emission from the C02 (v•) band. The maximum of the peak spectral radiance of this feature was observed at a rocket altitude of 92 km and had a value of about 130 MR/•m, which is nearly 2 orders of magnitude greater than that for an undisturbed atmosphere. By comparing upleg and downleg data, it was ascertained that the time constant for this excitation/radiation process is longer than 5 min. It is concluded that the excitation process involves vibrational excitation of nitrogen followed by collisional radiance v-v transfer to C02, which then radiates at 4.3 •m. The 5.3- and 2.8-um features are attributed to radiation from fundamental and firstovertone NO bands.