メタン・亜酸化窒素・フロン等の放射外力について

Abstract

The infrared radiative transfer model has been developed to estimate the earth'sradiation budget induced by the change in the concentrations of the greenhousegases such as C02, CH4, N20, CFCs and 03.We estimated the vertical distributions of the change in net downward longwaveradiation flux and the change in radiative heating or cooling rate due to theincrease in the greenhouse gases. The changes in the net downward longwaveradiation at the tropopause (I. E., the changes in surface-troposphere radiativeforcing) were estimated and expressed by the simple functions of the greenhousegas concentrations. We showed that the difference in the radiative forcing betweenwinter and summer is fairly large for the increases in C02, CFCs and tropospheric 03concentrations. The natural year-to-year variations in the net upward longwaveradiation flux at the tropopause is comparable to the change in the radiative forcingdue to the doubling of CO2 concentration.