> it would be good at some point to compare how things work in and near the El Niño basin to how they work somewhere else.
I was thinking along those lines too. One important thing that stands out in the "Covariance maps 1951-1979" image is that green turns into red about 3 pixels away from the basin. I don't know if that is special to that region. If ENSO is like a see-saw, then maybe the green-red border is like the pivot point. But it could be a general thing that happens over oceanic regions, or eveywhere.