Science China Earth Sciences

, Volume 59, Issue 11, pp 2213–2222 | Cite as

Estimating thermohaline variability of the equatorial Pacific Ocean from satellite altimetry

  • Che Sun
  • Xiao Ma
Research Paper


The vertical thermohaline structure in the western equatorial Pacific is examined with a Gravest Empirical Mode (GEM) diagnosis of in-situ mooring measurements. The poor GEM performance in estimating deep thermohaline variability from satellite altimetry confirms a lack of vertical coherence in the equatorial ocean. Mooring observation reveals layered equatorial water with phase difference up to 6 months between thermocline and sub-thermocline variations. The disjointed layers reflect weak geostrophy and resemble pancake structures in non-rotating stratified turbulence. A coherency theorem is then proved, stating that traditional stationary GEM represents in-phase coherent structure and can not describe vertically out-of-phase variability. The fact that stationary GEM holds both spatial and temporal coherence makes it a unique tool to diagnose vertical coherent structure in geophysical flows. The study also develops a non-stationary GEM projection that captures more than 40% of the thermohaline variance in the equatorial deep water.


Equatorial Pacific TRITON buoys Satellite altimetry GEM Vertical coherence 


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Copyright information

© Science China Press and Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  1. 1.Institute of OceanologyChinese Academy of SciencesQingdaoChina
  2. 2.National Laboratory for Marine Science and TechnologyQingdaoChina
  3. 3.State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of OceanographyState Oceanic AdministrationHangzhouChina

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