Composite eddy structures on both sides of the Luzon Strait and influence factors
Combining Argo observations with satellite remote sensing data during the period of 2002–2014, the mean three-dimensional structures of mesoscale eddies on both sides of the Luzon Strait (LS) were obtained via a composite method and analyzed to statistically examine the influences of background marine environment and the Kuroshio current on the eddy structures. The significant signals of temperature and salinity anomalies within the composite eddies extend much deeper in the region east of the LS (zone E) than those in the region west of the strait (zone W) because of stronger eddy intensity and larger vertical gradients of background temperature and salinity in the deep layer in zone E. In the vertical structure of temperature anomaly within the eddies, two cores occur at around 200 and 400 dbar depths, respectively, in zone E and only one core is centered at about 100 dbar in zone W. There is a clear three-core sandwich pattern in the vertical structure of salinity anomaly within the eddies in zone E. The Kuroshio water trapped in the eddy is responsible for abnormally positive salinity anomaly in the surface layer of the anticyclonic eddy center in zone W. On both sides of the LS, an asymmetric dipole structure in the surface layer gradually turns into a monopole one at depths, which resulted from the competition between horizontal advection effect and eddy pumping effect. The Kuroshio current influences the distribution patterns of isotherms and isohalines and enhances background temperature and salinity horizontal gradients on both sides of the LS, determining the orientations of dipole temperature and salinity structures within eddies.
KeywordsMesoscale eddy Composite structure Kuroshio current Luzon Strait
This study is a contribution to the international IMBER project. The daily SLA data were provided by the AVISO data project, and the daily satellite AVHRR SST data were obtained from the National Climatic Data Center (NCDC) of the National Oceanic and Atmospheric Administration (NOAA). The Argo float profiles were downloaded from the China Argo Real-time Data Center, and the Argo-only version of CARS was from the CSIRO (http://www.marine.csiro.au/atlas/).
This work was jointly funded by the State Key R&D project (grant no. 2016YFA0601103), the National Natural Science Foundation of China (grants 41776015 and 41276007), and President Research Award (2013121047).
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