A database of water transitions

Water vapour is the most important species for determining atmospheric properties: its the dominant absorber of sunlight and the major greenhouse gas. It is therefore obvious that any atmospheric models rely on using accurate data on the absorption properties of water vapour. Modern satellite measurements also demand very high accuracy from spectroscopic databases and many current satellite observations are degraded because of imperfect information on the absorption properties of water. There is a major demand to know the absorbtion properties of water to within 1%. This is very difficult to do using standard laboratory techniques where uncertainties less than 5%, when systematic errors are also properly accounted for, are very unusual. The proposal will combine ultra-high accuracy calculations of water transition intensities with all available laboratory measurements to give the best possible transition intensities data for the atmospheric community. It is my belief that for the majority of transitions it will be possible to compute intensities to better than 1% accuracy. This assertion will be systematically tested and the best possible intensity data will be used to populate a database which will be made widely available to other scientists via the web and via standard atmospheric databases such as HITRAN.