The Thermal Effects of Radiation

The thermal effects of solar and atmospheric radiation have been studied using mathematical models, generally by solving the radiative transfer equations which we have just described (e.g., Ramanathan, 1976). The most elaborate models, particularly those with fine spectral resolution, require rather large computing resources, and cannot be coupled with chemical or dynamical models using present computers unless they are greatly simplified. 

Middle atmosphere models calculate the spatial and temporal distribution of the net heating rate Q and the temperature not only as a function of altitude but also as a function of latitude, and even of longitude (local time). Such studies consider the multidimensional transport of heat and the solution of a thermodynamic equation like the one shown in Equation (3.10). The effect of waves should also be considered. Gravity wave dissipation, for example, may play an important role in the mesospheric heat budget. In the multidimensional models, the radiative scheme is often simplified and parameterized the most simple approach is to assume the cool-to-space approximation , in which it is assumed that exchange of heat between layers can be neglected in comparison to propagation out to space. 

The absorption of ultraviolet radiation by ozone in the Huggins and Hartley bands constitutes the principal source of heat in the stratosphere and mesosphere. The heating rate reaches 10 K/day near the stratopause on the average, with a maximum of about 15 K/day near the summer pole. The effect of the Huggins bands in the visible region becomes 

A parameterization of the atmospheric heating rate by O3 and O2 in different spectral regions has been suggested by Schoeberl and Strobel (1978), and is presented in Table 4.4. 

The infrared cooling in the middle atmosphere (e.g., by the 15 m CO2 band) can generally be calculated from the cool-to-space term of 

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The thermal effect of radiation absorption (for an absorbed dose of lOkGy, corresponding to 2.4 calories per gram, the water temperature... 

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