Properties of water complexes and their effect on atmospheric radiative transfer

The intense and extensive absorption of infrared and near infrared radiation by water in the atmosphere causes the largest contribution to the greenhouse effect. The importance of water in the atmosphere prompts the reexamination of its properties with special attention given to hydrogen bonded complexes (hydrates). Intermolecular interactions such as those responsible for condensation and cluster formation can significantly alter the optical properties and the reactivities of constituent monomers, affecting both atmospheric chemistry and climate.

The discussion of the climate effect of hydrated complexes will be evaluated for the example of pure water complexes of increasing size as well as binary complexes of water and abundant gases such as N2, O2, Ar and CO2. In this discussion, the sensitivity of model results to the abundance, the linewidths and vibrational frequencies of infrared absorption features will be reviewed and constrained by results of recent field measurements and laboratory studies. Remaining uncertainties in the fundamental data base will be highlighted. The fundamental data base required to calculate atmospheric abundances, absorption cross sections and photochemical yields of hydrates will be reviewed.