ENSO-like Variability 1900-2013

The historical record of ENSO-like variability in sea surface temperature (SST), sea level pressure (SLP) and sea level is examined, Time series of the SST and SLP indices defined in Zhang, Wallace, and Battisti (1997) are updated to include the past 20 years, which have been marked by a trend toward stronger equatorial trade winds and lower SST in the equatorial central and eastern Pacific. Sea level indices based on satellite altimetry (1993-2013), steric sea level estimated using XBT data (1950-2013), and longer tide gauge records from San Francisco and from Fremantle along the coast of southwest Australia are also used in the study. Time series of the indices are remarkably coherent on both interannual and interdecadal time scales and they portray a consistent account of ENSO-related variability extending back to the early 20th century. Consistent with previous studies, we find that global mean (and particularly tropical-mean) temperature is modulated by the ENSO-related variability, but we find no evidence of a consistent ENSO-related signal in the time rate of change of global-mean temperature. Hence, our analysis does not support the notion that the strength of the trade winds in the equatorial Pacific regulates the rate of oceanic heat storage.