Thermal infrared measurements in the middle and upper atmosphere

Abstract

The results of some sounding rocket experiments which sensed the upper mesosphere and the lower thermosphere in the infrared spectral regime are discussed. The rockets were launched at high latitudes from ESRANGE, Sweden, and each carried a liquid helium cooled grating spectrometer. Vibration-rotation bands of CO 2, O 3, H 2O, and NO were measured at mid infrared wavelengths. In the far infrared emissions from pure rotational transitions of H 2O and from the fine structure transition of atomic oxygen in its electronic ground state were recorded. Most of the payloads also carried an atomic oxygen sensor provided by Utah State University/Philipps Laboratory (USU/PL). This instrument uses the resonance fluorescence technique to derive oxygen densities in the thermosphere. Modelling of the atomic oxygen fine structure emission suggests that the fine structure levels are in local thermodynamic equilibrium in the lower thermosphere. The measured atomic oxygen densities allowed us to quantitatively model the ozone hot band excitation which agrees well with the observations.