CO2(ν2)-O quenching rate coefficient derived from coincidental SABER/TIMED and Fort Collins lidar observations of the mesosphere and lower thermosphere
1Centre National de la Recherche Scientifique/École Polytechnique, UMR8539, Palaiseau-Cedex, 91128, France
2The Catholic University of America, Washington DC, 20064, USA
3NASA Goddard Space Flight Center, Greenbelt, MD, 20771, USA
4Colorado State University, Fort Collins, CO, 80523, USA
5National Center for Atmospheric Research, Boulder, 80307, CO, USA
Abstract. Among the processes governing the energy balance in the mesosphere and lower thermosphere (MLT), the quenching of CO2(ν2)-O vibrational levels by collisions with O atoms plays an important role. However, there is a factor of 3–4 discrepancy between various measurements of the CO2-O quenching rate coefficient, kVT. We retrieve kVT in the altitude region 80–110 km from coincident SABER/TIMED and Fort Collins sodium lidar observations by minimizing the difference between measured and simulated broadband limb 15 μm radiances. The retrieved kVT varies from about 5 × 10−12 cm3 s−1 at 87 km to about 7 × 10−12 cm3 s−1 at 104 km. A detailed consideration of retrieval errors and uncertainties indicates deficiency in current understanding the non-LTE formation mechanism of atmospheric 15 μm radiances. An updated mechanism of CO2-O collisional interactions is suggested.