Seidel et al. (2007)
Also: Seidel et al. 2007
Widening of the tropical belt in a changing climate
Seidel, D.J., Fu, Q., Randel, W.J. & Reichler, T.J. (2007). Widening of the tropical belt in a changing climate. Nature Geoscience. 1(1),21-24. Article
https://doi.org/10.1038/ngeo.2007.38
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.