The natural greenhouse effect of atmospheric oxygen (O₂) and nitrogen (N₂)

Abstract

[1] The effect of collision-induced absorption by molecular oxygen (O 2 ) and nitrogen (N 2 ) on the outgoing longwave radiation (OLR) of the Earth's atmosphere has been quantified. We have found that on global average under clear-sky conditions the OLR is reduced due to O 2 by 0.11 Wm À2 and due to N 2 by 0.17 Wm À2 . Together this amounts to 15% of the OLR-reduction caused by CH 4 at present atmospheric concentrations. Over Antarctica the combined effect of O 2 and N 2 increases on average to about 38% of CH 4 with single values reaching up to 80%. This is explained by less interference of H 2 O spectral bands on the absorption features of O 2 and N 2 for dry atmospheric conditions.

O2−O2 and O2−N2 collision-induced absorption mechanisms unravelled

“…More recent measurements of collision-induced absorption typically use cavity ringdown spectroscopy to observe the weak collision-induced signal by achieving long path lengths [3][4][5][6][7][8][9][10][11] , rather than high pressures 12,13 . Roto-translational collision-induced absorption is important for the atmospheric heat balance 14 , and electronic transitions in O 2 , such as the A-band…”

Evaluating and improving the treatment of gases in radiation schemes: the Correlated K-Distribution Model Intercomparison Project (CKDMIP)

“…The concentrations of the second two gases may be treated as fixed both spatially and over the timescales commonly considered by climate models. O 2 is important mainly in the shortwave but reduces outgoing longwave radiation (OLR) by around 0.11 W m −2 globally (Höpfner et al, 2012). Absorption by N 2 is ignored by most operational radiation schemes, yet it reduces OLR by around 0.17 W m −2 (Höpfner et al, 2012) and, as will be shown in Sect.…”

Influence of Hydrological Perturbations and Riverbed Sediment Characteristics on Hyporheic Zone Respiration of CO2 and N2

“…Despite their small areal extent, rivers are increasingly recognized as significant hot spots for global carbon (C) and nitrogen (N) degradation and associated greenhouse gas emissions (Battin et al, ; Gomez‐Velez et al, ; Höpfner et al, ; Hotchkiss et al, ; Peyrard et al, ). The significance of biogenic CO 2 and N 2 gas production due to heterotrophic microbial activity in rivers and associated hyporheic zones to the overall carbon balance of rivers is poorly quantified, yet net heterotrophy is estimated to be 0.32 Pg C yr −1 , with half of terrestrial organic carbon stored or transformed in aquatic systems (Battin et al, ).…”