Dai (2006)
Also: Dai 2006
Recent climatology, variability, and trends in global surface humidity
Dai, A. (2006). Recent climatology, variability, and trends in global surface humidity. Journal of Climate, 19(15), 3589-3606. Link to PDF
doi: 10.1175/JCLI3816.1
References
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.