Upper atmosphere



Theoretical understanding of the upper atmosphere and the complex physical processes responsible for its composition, dynamics, and thermal behavior has improved to the point where reasonable three-dimensional, time-dependent models of the atmosphere above about 100 km exist. These models have been extensively refined through comparisons with experimental data from coordinated, multistation ground-based investigations. Theoretical calculations using a state-of-the-art model of the upper atmosphere indicate that over the next century, the anthropogenic production of CO2 , which is anticipated to warm the lower atmosphere, will also cool the upper atmosphere. The model predicts that doubling atmosphere CO2 cools the mesosphere (80–100 km) by about 10°C and the thermosphere (above 100 km) by about 50°C.