Graham: how did you first find this Niño 3.4 data, and why did you choose to work with it?

* [http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/detrend.nino34.ascii.txt](http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/detrend.nino34.ascii.txt)

I can't find it here:

* Monthly atmospheric and SST indices, NCEP-NOAA, [http://www.cpc.ncep.noaa.gov/data/indices/](http://www.cpc.ncep.noaa.gov/data/indices/)

a website that lists a variety of indices including Niño 3.4. I'm curious because the data you're using may have been "detrended" in some way, and Ludescher _et al_ don't seem to say where they got their Niño 3.4 data.