Abstract
In order to incorporate the radiative process into a dynamical model for forcasting the development of fog or stratiform cloud, a method of calculating the rate of radiative temperature change has been developed by applying the P3-approximation method to a foggy atmosphere. We took into account absorption, scattering, and scattering and absorption of solar radiation by ozone, air molecules and water droplets, respectively, in the visible region, absorption of solar radiation by the near infrared bands of water vapor, and scattering and absorption of solar radiation by water droplets in the near infrared region. In the infrared region, we considered absorption and emission of thermal radiation by 6.3μm and rotational bands of water vapor, 15μm band of carbon dioxide and continuum band of water dimer as well as scattering, absorption and emission of thermal radiation by water droplets.
Comparisons of the flux divergence estimated by the present method with that by the discrete ordinates method of high accuracy showed that the accuracy of this approximation is sufficient for the estimation of radiative effects on the evolution of fog or stratus.
