Water Circulation and Transport Time Scales in the Beagle Channel, Southernmost Tip of South America

Abstract

The Beagle Channel is a long and narrow interoceanic passage within the Tierra del Fuego archipelago in the southernmost tip of South America. A high-resolution 3D hydrodynamic model based on the finite elements method was applied to investigate the residual circulation, water fluxes and transport time scales inside this channel. Numerical solutions were analyzed at seasonal time scale and the model results compared with observed ocean data. The circulation pattern is characterized by a west-to-east residual flow with low intensity and low seasonal variability. The water fluxes through the channel were estimated to be, on average, around 12,700 m3/s, with inflow through its western entrance and eastwards outflow mainly through the Mackinlay Strait. The water residence times vary seasonally with basin averages between 36 and 43 days and maximum values between 53 and 95 days. The results provide an overview of the hydrodynamics and water residence times in the Beagle Channel, a unique ecosystem threatened by recent anthropogenic pressures and climate change.

Multiple controls on carbon dioxide sequestration in the beagle channel (Southern Patagonia) in early fall

“…The phytoplankton growth also shows a pronounced seasonality, between low biomass during fall-winter and massive increases during spring-summer, indicated by minimum surface values in winter (~0.1 μg C L -1 ) and peak values in early spring (up to 141 μg C L -1 ), respectively (Almandoz et al, 2019(Almandoz et al, , 2011. Higher vertical summer stratification (i.e., warmer and fresher surface waters) together with more sluggish circulation (Cucco et al, 2022), increase the availability of plankton-derived organic matter, causing an increase in respiration that may cause oxygen depletion in bottom waters (Martin et al, 2016;Flores Melo et al, 2020).…”

“…The bathymetric contrasts along the oceanographic transect may pose restrictions to the water flow along the channel and hence influence zonal gradients in seawater properties (Giesecke et al, 2021;Martín et al, this issue) and water residence times (Cucco et al, 2022). In particular, the topographic sill at Mackinlay Strait (minimum depth about 15m) has been signalled in the past as a physical barrier that imposes different physical and biological properties to the east and west (e.g.…”