The Sun is the climate pacemaker I. Equatorial Pacific Ocean temperatures

• Central Pacific region temperature dataset SST3.4 from 1990 to 2014 is studied.
• SST3.4 contains a sustained signal at 1.0 cycle/yr implying solar forcing.
• SST3.4 also contains a signal (<1 cycle/yr) showing El Niño/La Niña effects.
• This signal contains segments of period 2 or 3 years, phase locked to the annual.
• A 12-month moving average improves on a “climatology” filter in removing annual effects.

Equatorial Pacific Ocean temperature time series data contain segments showing both a phase-locked annual signal and a phase-locked signal of period two years or three years, both locked to the annual solar cycle. Three such segments are observed between 1990 and 2014. It is asserted that these are caused by a solar forcing at a frequency of 1.0 cycle/yr. These periodic features are also found in global climate data (following paper). The analysis makes use of a twelve-month filter that cleanly separates seasonal effects from data. This is found to be significant for understanding the El Niño/La Niña phenomenon.