Radiative forcing calculations for SF(sub 6) and CH(sub 4) using a correlated k-distribution transmission model.

摘要

A correlated k-distribution model for the atmospheric transmission of major molecular species has been used to calculate the tropospheric radiative forcing for the ground state, v(sub 3) band of SF(sub 6) and CH(sub 4). A mid latitude summer, clear sky approximation, temperature-pressure distribution was used in the radiative transfer calculations. For the SF(sub 6) calculations a value of 0.26 W/m(sup 2) was obtained for the v(sub 3) band forcing using a new value of the measured integrated band absorption for SF(sub 6). The abundance used was 1 ppbv of SF(sub 6). Hot band contributions to the forcing are estimated to be on the order of three times the value of the v(sub 3) value giving a total radiative forcing of about 0.73 W/m(sup 2). For the CH(sub 4) calculation a value of 1.71 W/m(sup 2) was obtained and this number agrees with previously published CH(sub 4) radiative forcing values to with four percent. The radiative forcing calculation for SF(sub 6) issued to estimate the global warming potential (GWP) of SF(sub 6) using an approximate model developed to provide reasonably 000 accurate GWPS. The results give GWPs for SF(sub 6) of the order of 12000--25000 (CO(sub 2) = 1). We estimate the likely range of the radiative forcing and GWP values based on two recent measurements of the total integrated band strength of SF(sub 6). Comparison of the GWPs of SF(sub 6) to those of CF(sub 4) (3600--8500) and CFC-11 (4500--1400) indicates that SF(sub 6) has the potential to be a major greenhouse gas if large amounts are introduced into the atmosphere.