Evidence of non-LTE in the CO₂ 15 μm weak bands from ISAMS and WINDII observations

An analysis of the measurements of the CO₂ 15 μm radiance emission by the UARS/ISAMS 30W channel and the kinetic temperature from UARS/WINDII taken on July 21, 1992 at northern latitudes around the mesopause is presented. The modeling of the measurements clearly show evidence of non-LTE emissions in the CO₂(v₂=1) levels of the minor isotopes 636, 628, and 627 in the 70-90 km region. A comparison with non-LTE model predictions by López-Puertas et al. [1992a] shows a good agreement within the errors in the measured quantities. This constitutes the first experimental evidence of non-LTE emissions in these CO₂ 15 μm weak bands. The measurements also represent indirect evidence of the net radiative heating produced by these bands around the summer mesopause.