International Reference Atmosphere: Thermosphere Models Pt.1

The Committee on Space Research (COSPAR) International Reference Atmosphere (CIRA) first appeared in 1961 and has been subsequently supplemented by work published in 1965 and 1972. CIRA 1986, the fourth in the series, is published in two parts, Part I: Thermosphere Models and Part II: Middle Atmosphere Models. In CIRA 1986 Part I: Thermosphere Models, an attempt has been made to highlight the major fundamental causes of the large degree of variability which is a very important characteristic of the thermosphere. These are dealt with by empirical description of observed effects, by a theoretical and numerical modelling approach, and by detailed discussion and analysis of observations. The numerical modelling approach has been used to simulate the thermosphere under both quiet and disturbed conditions. Strong forcing at times of high geomagnetic activity causes a wide range of profound thermospheric changes, observed as major and rapid changes of the structural properties of density, temperature and composition, and in the generation of large local and global wind and circulation disturbances.