Comparison of observed and modeled longwave radiances

Calculated LW radiances based on NMC profiles of temperature and humidities for the month of July 1985 are obtained using standard procedures for performing radiative transfer calculations, and are within 3 percent (against a standard deviation of 4 percent) for global daytime land comparsions and within 1 percent (against a standard deviation of 1.5 percent) for a case study located over North America. The calculated values over the global data set show a slight trend with the surface temperature, and since there is no obvious trend with the column amount of water vapor, it is argued that the trend with temperature is evidence that absorption by other components (i.e., CO2O3 and other trace gases not included in these calculations) in the model could be improved.