Impact of new measurements of oxygen collision-induced absorption on estimates of short-wave atmospheric absorption

Abstract

A new set of laboratory measurements of the 1.06 μm and 1.27 μm collision-induced bands of gaseous oxygen is presented. Absorption by pure oxygen and mixtures of oxygen with nitrogen and argon was observed using a Fourier transform spectrometer for temperatures between 230 and 295 K and pressures between 1 and 5 bar. Binary cross-sections derived from the measurements were used to estimate the impacts on estimates of clear-sky climatological absorption of solar irradiance. Monthly climatological atmospheric profiles averaged over 10° latitude belts were used to study the temporal and annual variation of the impacts. The global- and annual-mean clear-sky extra-absorption was 0.58 W m-2 (about 1% of the absorption by water vapour and ozone), 0.42 W m-2 due to the 1.27 μm band and 0.16 W m-2 due to the 1.06 μm band. If estimates for other oxygen collision-induced bands taken from previous studies are added, an overall impact of about 1 W m-2 results.