Altitude Distribution of O₂ 1.27μm Nightglow Emission Observed by a Rocket-Borne Radiometer

抄録

The O₂ 1.27μm nightglow emission was observed by using a rocket-borne radiometer equipped with a high sensitive Ge sensor cooled by liquid nitrogen. The radiometer was flown on board the S-310-20 rocket launched at 04:30 JST, approximately 11 hours after local ground sunset, on January 28, 1990 from Kagoshima Space Center (31°N, 131°E), Japan. As the noise equivalent radiance at 1.27μm was only ±1.2kR when the time constant was 10ms, very fine data were obtained. The total zenith intensity was 207.1±2.4kR, which was 2-3 times as strong as those previously observed. The volume emission rate as a function of altitude showed two-layer structure, and the integrated intensity of a major layer centered at 92km was about 4 times as strong as that of the minor layer at 83km. The direct excitation by the three-body recombination of atomic oxygen could explain the emission of the major layer, when the excitation efficiency for O₂(¹Δ_g) is 0.75. The minor layer was found to be explained by an energy transfer from vibrationally excited OH to O₂.