OH rotational temperatures at Davis, Antarctica, via scanning spectrometer

Spectra of the OH[8-3] Meinel band were recorded via scanning spectrometer at Davis, Antarctica (68.6°S, 78.0°E), during the austral late autumn to early spring, 1987. From the P 1 branch intensity distribution, rotational temperatures, averaged over periods of 30–90 min were obtained. A test for approximation to the Boltzmann distribution of the rotational energies was employed, and its scatter matched to computer modelled error distributions. A most probable seasonal average rotational temperature of 205 K (±5 K at the 95% confidence level) was deduced, in good agreement with current models of kinetic temperature at 85 km altitude. A mesopause temperature between 180 and 190 K is inferred. The seasonal trend exhibited an abrupt post-midwinter cooling, and is in poor agreement with the models.