David I share most of your sentiments above.

Ludescher paper is bothersome for me but I do not want to babble anything about it here due to John's status in academia, being respectful of John course. However I have very very strong opinions on that paper.

I believe in such network link model if it also includes the vertical North-South variations, since clearly I showed in most of the Sig data for volumetric surface data there is a **Trend** corresponding to North South oscillation.