VERTICAL STRUCTURE OF THE MIDLATITUDE TEMPERATURE FROM STRATOSPHERE TO MESOPAUSE (30 KM - 105 KM)

Data sets from Rayleigh lidar (1979-93) at the Observatory of Haute-Provence (44-degrees-N, 6-degrees-E) and at Biscarrosse (44-degrees-N, 1-degree-W) of southern France, and from narrowband Na lidar (1991-4) at Fort Collins, Colorado (41-degrees-N, 105-degrees-W) are used to deduce the vertical temperature structure of the midlatitude middle atmosphere from 30 - 105 km. Nightly averaged temperatures measured across the Atlantic at comparable latitudes between 81 and 90 km showed seasonal variations tracking one another. Harmonic analyses of the measured profiles at these sites have been compared to the reference atmosphere, CIRA 1986. Considerable differences are noted in the annual mean temperatures in the mesopause region. Two temperature minima at 86 and 99 km are observed, suggesting heating and cooling mechanisms not previously incorporated into the reference atmosphere. Using the new 3D TIME-GCM of Roble and Ridley which includes both dynamical and chemical processes, we account for this anomalous behavior by model simulation for the first time. Except the existence of strong semi-annual oscillations, the observed annual and semi-annual temperature variations are compatible with CIRA 1986. Observed annual temperature and solar flux forcing are out-of-phase between 65 and 99 km, reflecting a dynamics dominated atmosphere at these altitudes.