A Global Climatology of O2⋅O2, O2⋅N2, and (H2O)2 Abundance and Absorption

Recent experimental and theoretical results show that the collision pairs, O2⋅O2 and O2⋅N2, absorb a small but significant fraction of the globally incident, solar radiation (Pfeilsticker et al. 1997, Solomon et al. 1998, Mlawer et al. 1998). The contribution of the water vapor dimer to shortwave (SW) absorption, however, remains speculative due to uncertainties in both its abundance and its absorption cross section (Chvlek and Geldart 1997, Clvlek et al. 1998, Tso et al. 1998). This study employs a specially modified version of the National Center for Atmospheric Research (NCAR) Community Climate Model, Version 3 (CCM3) general circulation model (GCM) to quantify the global abundances and SW radiative forcings of O2⋅X (O2⋅X ≡ O2⋅O2 + O2⋅N2) and (H20)2, and the present uncertainties in these quantities.