Recurrence method for calculation of atmospheric cooling rate due to infrared radiation

A computational method for the mean slab transmissivities of water vapour and CO2 and a recurrence me-thod for the atmospheric cooling rate due to infrared radiation are developed and discussed in some detail in this paper.At first the spectra of water vapour and CO2 are divided into 10 and 2 basic bands according to the experi-mental data; then an analytic and universal expression of the mean slab transmissivity in those bands is obtained and checked with the experimental data at 220o, 260o and 300oK. Results show that the computational method developed in this paper has quite good accuracy, and therefore it can be used in the GCMs for calculations of the atmospheric cooling rates.The recurrence method for calculations of the upward and the downward fluxes of infrared radiation is de-rived and checked. It is proved that the method has a similar accuracy as others, but saves a lot of computation time. At last a simplified method of the transmissivity calculation, i.e. the tabulation method, is developed and its accuracy is checked as well.