I used
https://github.com/azimuth-project/el-nino/blob/master/R/grj/nino34-anoms.txt

I looked at some analyses, but there's too much going on to keep track, so I don't know if I have seen what you want me to. I didn't see a plot of nino34 and link strength together so that "strength tends to decrease during El Nino events" could be assessed visually.