Efficient line-by-line calculation of absorption coefficients

An efficient algorithm of evaluating absorption coefficients line-by-line for the purpose of integrating the radiative transfer equation with emphasis on the Earth's atmosphere is presented. The main problems associated with such an algorithm are concerned with line shape, the treatment of lines outside the spectral range of interest, and the way in which spectral sampling is performed. These are considered together with methods improving speed of computation in general. Results and intercomparisons from applications of the algorithm are presented. (C) 1999 Elsevier Science Ltd. All rights reserved.