Open AccessOceanographic observations in Chilean coastal waters between Valdivia and Concepción
Author(s) -
Atkinson Larry P.,
ValleLevinson Arnoldo,
Figueroa Dante,
De PolHolz Ricardo,
Gallardo Victor A.,
Schneider Wolfgang,
Blanco Jose L.,
Schmidt Mike
Publication year - 2002
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2001jc000991
Subject(s) - upwelling , oceanography , stratification (seeds) , geology , submarine pipeline , eddy , advection , salinity , temperature salinity diagrams , sea surface temperature , surface runoff , meteorology , geography , seed dormancy , ecology , botany , germination , physics , dormancy , turbulence , biology , thermodynamics
The physical oceanography of the biologically productive coastal waters of central Chile (36° to 40°S) is relatively unknown. In December 1998 we made a short exploratory cruise between Valdivia (40°S) and Concepción (37.8°S) taking temperature, salinity, oxygen, and current velocity profiles. Coincident sea surface temperature and color measurements were obtained by satellite. The results showed an area dominated by wind‐induced coastal upwelling, river runoff, intrusion of offshore eddies, mixing, and heating. Upwelling centers were found over the shelf at three locations: inshore of Mocha Island, off Valdivia, and off Lavapie Point. At these centers, equatorial subsurface water (ESSW) intrudes into the coastal waters, sometimes affecting the surface waters. Since ESSW has characteristically low‐oxygen and high‐salinity values, it is easily detected. Off Valdivia, runoff imparts stratification, while farther north, solar heating and reduced mixing may facilitate stratification. In some areas, even strong winds would not destroy the stratification imparted by the advection of buoyancy that occurs during the upwelling process. Strong equatorward currents (>1 m s −1 ) in the form of an upwelling jet were found off Lavapie Point. This is also the location of an intruding anticyclone. Elsewhere, currents were mainly northward but highly variable because of intrusions from offshore eddies. The sea surface temperature and ocean color images show a complex field of onshore and offshore intrusions combined with the effects of mixing on chlorophyll concentrations. The residence time of upwelled water on the shelf is estimated to be less than 1 week.