Measurements and Modelling of Water Vapour Spectroscopy in Tropical and Sub-arctic Atmospheres

Water vapour plays in important role in the energy budget of the atmosphere. Despite many years of study there are still considerable uncertainties both in the measurement of water vapour and it’s representation in radiation models. In an attempt to reduce these uncertainties two field experiments in differing atmospheres were conducted in 1999. The results from a tropical atmosphere and a sub-arctic atmosphere show significant differences between differing radio sonde sensors. Microwave radiometer measurements are used to validate radiation models and also to constrain the input profile for thermal infra-red modelling. Results from the GENLN2 v4 line-by-line radiation model with the CKD2.4 water vapour continuum show very good agreement with airborne interferometer measurements in the thermal infra-red.