Estimating thermohaline variability of the equatorial Pacific Ocean from satellite altimetry  

作　　者：SUN Che MA Xiao 

机构地区：[1]Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China [2]National Laboratory for Marine Science and Technology, Qingdao 266071, China [3]State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China

出　　处：《Science China Earth Sciences》2016年第11期2213-2222,共10页中国科学（地球科学英文版）

基　　金：supported by the National Basic Research Program of China (Grant No.2012CB417400);the National Natural Science Foundation of China (Grant Nos. 41576017 & U1406401)

摘　　要：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.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.

关 键 词：Equatorial Pacific TRITON buoys Satellite altimetry GEM Vertical coherence 

分 类 号：P715.6[天文地球—海洋科学] P731.27