We may be at cross-purposes here. I am not convinced that anybody, including Ludescher et al, understands what it is that their link strength actually measures. Whether it should be called a link strength is dubious. There's no compelling reason why you should be interested in their definition, but if you are, I just wanted to warn you that its *weird*!
I put [some preliminary tests](http://www.azimuthproject.org/azimuth/show/Experiments+with+varieties+of+link+strength+for+El+Ni%C3%B1o+prediction) on the wiki.

> I keep thinking that correlations on very short time scales are indistinguishable from autocorrelation. Pick a location just outside the NINO34 region and any autocorrelation in the NINO34 region can easily leak into the outer regions.

What might be interesting is that the degree to which the correlations leak out of the basin (or more likely leak in given the prevailing winds) could vary over time. Maybe, steady trade winds lead to strong correlations of daily fluctuations between regions up say 2000km apart and a time lag of up to a few days. When the trade winds falter, these correlations drop.