McLean, J. D., C. R. de Freitas, and R. M. Carter (2009), Influence of the Southern Oscillation on tropospheric temperature, J. Geophys. Res., 114, D14104, doi:10.1029/2008JD011637.
http://www.agu.org/pubs/crossref/2009/2008JD011637.shtml
From the abstract:
Change in SOI accounts for...