Global greenhouse cooling in the upper atmosphere

Discusses long-term changes in the upper atmosphere resulting from man-made increases of concentrations of carbon dioxide and methane in the lower and middle atmosphere. According to computations using the Thermosphere/Ionosphere General Circulation Model (TIGCM) of the National Center for Atmospheric Research (R.G. Roble and R.E. Dickinson, Geophys. Res. Lett. 16, 1441 (1989)), the assumed doubling of the mixing ratios of CO/sub 2/ and CH/sub 4/ will cause the mesosphere at around 60 km height to cool by about 10 K, and the thermosphere above 100 km by up to 40 K. The resulting thermal contraction will lower the height of the ionospheric layers and cause changes in radiowave propagation conditions.<
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