>As usual, I can't comment too much because I have no feel for how their simulations work.

at least for some aspects it seems you rather don't need simulations.
they wrote ( in the blog post)
>our results document a much more active role for the Atlantic Ocean in determining conditions in the other two ocean basins.
and
>Seeing the Atlantic as an important contributor to these rainfall shifts, which happen as far away as Australia, came to us as a great surprise.

that is at least I found last july that already the NOAA images document a much more active role for the Atlantic Ocean in determining conditions, that is I wrote:
> it looks that the heat transfer of temperatures over the northern atlantic to the basin in front of northern south America seem to play a bigger role.

....even though this was based on an oversimplifying wind image on Wikipedia
I find though their explanation (at least the excerpts I see here) of the ENSO mechanism not convincing and the above image rightous misleading.

> I think that the most significant forcing function for ENSO is QBO, which is a global oscillation in wind direction.

I also think that QBO plays an important role in understanding the ENSO mechanism. The QBO itself seems to be driven by quaterly changes of westerlies and easterlies in the stratosphere (just watch this movie in the link, I think you had posted once: http://www.ugamp.nerc.ac.uk/hot/ajh/qbo.htm), which are as I understood basically the same for all longitudes (? at least thats what the ugamp site suggests in my interpretation) so the QBO period seems rather strictly 2 years with some outliers which produce those average of 2.3 years (....as I keep saying). The reason for this "strictly biannual period" might be some kind of period doubling of the quaterly/annual period or some planetary biannual thing. The ENSO will probably be mostly influenced by the lower parts of the QBO (which seem roughly still rather located at the upper boundary of the troposphere at 40-90mB). What I have sofar understood from the ugamp images is that the reason for an ENSO are so to say "overstrong lower easterlies" (like in Fig1 lower easterlies peak roughly in JUL 92,94,96 and 98) and as you can see the QBO easterlies in 1994 was rather strong (dark blue around 10mB) and indeed it looks as if there was some kind of El nino in 1994 (I don't know though if this was officially an El Nino by those SOI Nino3.4 or what do I know indicators) so in terms of the Atlantic: apart from the westerlies from north in autumn 94 (fig1) the westerlies from north 2 years before the El Nino (here Fig. 1 westerlies autumn 1992 and how (un)cool these are (and in particular wether their temperatures are different when coming from northern Atlantic or Pacific (see chimney explanation)) may also play a role. But actually one would need much better and more image material for any sound deduction, which I don't have access to. Moreover I can't spend too much time investigating this (I have currently a rather many strenous hours in front of computer sitting job)-so this reasoning here should be for now taken with a huge grain of salt.