NONLOCAL THERMODYNAMIC-EQUILIBRIUM LIMB RADIANCE NEAR 10 MU-M AS MEASURED BY UARS CLAES

Observations have been made of non-local thermodynamic equilibrium (no n-LTE) limb radiance at 923 cm(-1) (10.83 mu m) using the Cryogenic Li mb Array Etalon Spectrometer (CLAES) aboard the Upper Atmosphere Resea rch Satellite (UARS). We study the relative contributions from CO2 and O-3 in three CLAES channels and examine the correlation with solar ze nith angle. The moderate spectral resolution of CLAES allows us to dis criminate the individual radiance contributions of the CO2 isotopic an d O-3 hot bands. The analysis shows good agreement between measured an d calculated radiances and confirms our previous theoretical modeling of the non-LTE populations of these states. The diurnal variation of t he measured emission points to solar dependent mechanisms selectively populating molecular vibrational levels in CO2 and O-3. These processe s are shown to affect the limb radiance for limb view tangent heights above about 38 km at the frequencies studied here. The measurements al so show further experimental evidence for the excitation of the CO2(nu (3)) mode by the energy transfer from electronically excited O(D-1) th rough N-2(1). This study is intended as a precursor to the inclusion o f these effects in the operational CLAES data analysis.