Conclusione. I centri della cultura umanistica in Europa

1. Per prima cosa, desidero ringraziare l’Accademia delle Scienze di Torino, il suo attuale Presidente, Professore Angelo Raffaele Meo ed il passato Presidente e ottimo organizzatore di questo Convegno, Professore Pietro Rossi, per avermi incaricato di concludere le nostre giornate di lavoro, dedicate alla memoria dell’indimenticabile amico e generoso Maestro, Franco Simone, che impegnò la massima parte del suo ammirevole magistero nelle ricerche storiche sull’Umanesimo europeo. Né l’Accademi..

Large Amplitude Perturbations in Mesospheric OH Meinel and 87-km Na Lidar Temperatures Around the Autumnal Equinox

Two high‐precision CEDAR instruments, an OH Mesospheric Temperature Mapper (MTM) and a Na Temperature Lidar, have been used to investigate seasonal variability in the mid‐latitude temperature at ∼87 km altitude over the western USA. Here we report the observation of a large perturbation in mesospheric temperature that occurs shortly after the autumnal equinox in close association with the penetration of planetary‐wave energy from the troposphere into the mesosphere. This perturbation has been observed on three occasions and exhibits a departure of up to ∼25–30 K from the nominal seasonal trend during a disturbed period of ∼2 weeks. Such behavior represents a dramatic transient departure from the seasonal trend expected on the basis of current empirical models. These novel results coupled with a recent TIME‐GCM modeling study [Liu et al., 2000] provide important insight into the role of planetary waves in mesospheric variability during the equinox periods