Phase-locked states and abrupt shifts in Pacific climate indices

•Five Pacific climate indices show that the Pacific climate system alternates between two regimes: Solar cycle (SOL), Teleconnections (TEL).•During SOL each index shows two components that are phase locked to the solar cycle.•The first SOL component is at the annual cycle, while the second is at a subharmonic of the annual cycle.•During TEL abrupt climate shifts occur.

Douglass has shown that ENSO index aNino3.4aNino3.4 contains segments phase locked to subharmonics of the annual solar cycle and also that a set of indices including aNino3.4aNino3.4 shows abrupt shifts between these phase-locked states. Here, four additional Pacific indices are studied. These five indices show that the Pacific climate system alternates between two regimes: (1) Solar cycle (SOL), (2) Teleconnections (TEL). During SOL each index shows two components that are phase locked to the solar cycle. The first is at the annual cycle, while the second is at a subharmonic of the annual cycle. During TEL abrupt climate shifts occur.