Abstract

The high resolution (1 cm^-1) limb emission spectra taken with the CIRRIS 1A interferometer on STS-39 over tangent heights from 50 to 200 km provides an opportunity to test the detailed non-LTE models of the emission and investigate methods for determining the carbon budget of the lower thermosphere from coincident measurement of the 4.3 μm CO₂ v₃ band and the 4.7 μm CO band. Earlier theory (Kumer and James, 1977, López-Puertas et. al., 1986, López-Puertas and Taylor, 1989) did not have high resolution spectral data to thoroughly validate their theories. López-Puertas and Taylor (1989) compared their models to SAMS data, a situation that needed an additional line-by-line model to filter their model results in a manner similar to the pressure modulated radiometer measurement. The high resolution spectra provide a much more stringent test of the theoretical non-LTE infrared emission models. We limit our discussion to the daytime spectra for a number of reasons. (1) The solar excitation leads to a large increase in signal, increasing the altitude to which good spectra can be obtained, (2) the domination of solar excitation simplifies the determination of the CO and CO₂ densities since other non-local earthshine processes become less important, and (3), the solar excitation of the CO₂v₃ states yields a rich spectrum including isotopic and hot-band emission.

© 1993 Optical Society of America