The interdecadal Pacific oscillation (IPO) is an oceanographic/meteorological phenomenon similar to the Pacific decadal oscillation (PDO) but for a wider area of the Pacific. Significantly it covers the Southern hemisphere as well as the Northern hemisphere (50°S to 50°N).
The IPO had positive phases (southeastern tropical Pacific warm) from 1922 to 1946 and 1978 to 1998, and a negative phase between 1947 and 1976.
References
Interdecadal Pacific Oscillation Wikipedia(Text) CC BY-SA