New cross sections for the absorption of near ultraviolet radiation by nitrous oxide (N 2 O)

A re‐investigation of the ultraviolet absorption spectrum of nitrous oxide (N 2 O) agrees with previous results in the range 210 to 235 nm, but contrary to previous results it indicates a vanishingly small cross section above 260 nm. The absence of the relatively long wave length absorption implies a negligible rate of photolysis of nitrous oxide in the troposphere. These results plus the previously estimated atmospheric mean residence times of N 2 O indicate that there is a large, unknown tropospheric sink for nitrous oxide.