Spatial structure of hydrography and flow in a Chilean fjord,Estuario Reloncaví |
| |
| Authors: | Arnoldo Valle-Levinson Nandita Sarkar Rosario Sanay Doris Soto Jorge León |
| |
| Institution: | (1) Civil and Coastal Engineering Department, University of Florida, 365 Weil Hall, FL 32611-6580 Gainesville, USA;(2) Code 614, Observational Science Branch, NASA Wallops Flight Facility, Rm. E226, Bldg. N-159, VA 23337 Wallops Island, USA;(3) Centro de Estudios del Cuaternario Fuego-Patagonia (CEQUA), Instituto de Fomento Pesquero, Punta Arenas, Chile |
| |
| Abstract: | Underway current velocity profiles were combined with temperature and salinity profiles at fixed stations to describe tidal
and subtidal flow patterns in the middle of the northernmost Chilean fjord, Estuario Reloncaví. This is the first study involving
current velocity measurements in this fjord. Reloncaví fjord is 55 km long, 2 km wide, and on average is 170 m deep. Measurements
concentrated around a marked bend of the coastline, where an 8-km along-fjord transect was sampled during a semidiurnal tidal
cycle in March 2002 and a 2-km cross-fjord transect was occupied, also during a semidiurnal cycle, in May 2004. The fjord
hydrography showed a relatively thin (<5 m deep), continuously stratified, buoyant layer with stratification values >4 kg
m−3 per meter of depth. Below this thin layer, the water was relatively homogeneous. Semidiurnal tidal currents had low amplitudes
(<10 cm s−1) that allowed the persistence of a surface front throughout the tidal cycle. The front oscillated with a period of ca. 2.5
h and showed excursions of 2 km. The front oscillations could have been produced by a lateral seiche that corresponds to the
natural period of oscillation across the fjord. This front could have also caused large (2 h) phase lags in the semidiurnal
tidal currents, from one end of the transect to the other, within the buoyant layer. Tidal phases were relatively uniform
underneath this buoyant layer. Subtidal flows showed a 3-layer pattern consisting of a surface layer (8 m thick, of 5 cm s−1 surface outflow), an intermediate layer (70 m thick, of 3 cm s−1 net inflow), and a bottom layer (below 80 m depth, of 3 cm s−1 net outflow). The surface outflow and, to a certain extent, the inflow layer were related to the buoyant water interacting
with the ambient oceanic water. The inflowing layer and the bottom outflow were attributed to nonlinear effects associated
with a tidal wave that reflects at the fjord's head. The weak subtidal currents followed the morphology of the bend and caused
downwelling on the inside and upwelling on the outside part of the bend. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
