Pathways of Deep and Bottom Water in the Southwestern Brazil Basin:
(A local Synthesis of WOCE  Hydrographic and Direct Velocity Measurements)


 
 

Michal Vanicek
Woods Hole Oceanographic Institution
Woods Hole, Massachusetts, USA
mvanicek@whoi.edu
 
 
 

Nelson G. Hogg
Woods Hole Oceanographic Institution
Woods Hole, Massachusetts, USA
nhogg@whoi.edu

Abstract

The Vitoria-Trindade Seamount Chain near 20S in the Western Brazil Basin is an important topographic barrier which  interrupts the Deep Western Boundary Currents of both the southward flowing deep water, and the northward flowing bottom water. We present and compare the flow patterns of these two water masses in this region as obtained three different ways:

  1. from the neutrally buoyant float experiment at NADW and AABW levels,
  2. from the hydrographic measurements,
  3. and most importantly from a synthesis of hydrographic and direct velocity measurements using a local, linear, box inverse model.
We focus on the DWBC and on the zonal flow offshore. The existence of the DWBC is quite clear in the float data at the NADW level, but is less prominent at the AABW level. In the interior the hydrographic data suggest a clear separation in the direction of the deep water, zonal flow in agreement with the floats which were mainly displaced zonally with unexpectedly mall meridional space scales. Floats deployed more offshore at the NADW level continue to the east after arriving at the Vitoria-Trindade Seamount Chain while floats placed closer to he coast suggest a return to the western boundary.