The metronome of ENSO is the steady eastward drift of equatorial atmospheric convection centers. The natural position of a convection center is over the warmest water; drift displaces it (and the warmest water) in a quasi-regular manner. When it is far enough downstream, a new center regenerates in its home position, beginning the cycle again.
"ENSO, Climate Variability, and the Rapanui: Part 2. Oceanography and Rapa Nui,"
Rapa Nui Journal: Journal of the Easter Island Foundation: Vol. 15
, Article 4.
Available at: https://kahualike.manoa.hawaii.edu/rnj/vol15/iss2/4