Geophysical Research Letters

The global ocean imprint of ENSO



[1] The ENSO-related spatial patterns and global averages of ocean temperature, salinity, and steric height are estimated from over 7 years of Argo data, 2004–2011. Substantial extratropical variability is seen in all variables in addition to familiar tropical ENSO signals. Surface layer (0–100 dbar) and subsurface (100–500 dbar) temperature variations are both important in determining steric height and sea surface height patterns. For the two years prior to the 2009 El Niño, the upper 100 dbar of the ocean gained 3.3 × 1022 J yr−1 of heat, while the 100–500 dbar layer lost a similar amount. The ENSO-related vertical redistribution of globally-averaged heat content between surface and subsurface layers, occurring throughout the record, is due primarily to changes in the east-west tilting of the equatorial Pacific thermocline. The large temperature changes in the individual layers mask the smaller vertically-averaged temperature change, in which the ocean loses heat when the surface layer is anomalously warm and gains heat when the surface layer is cool.