Direct velocity measurements in the Samoan passage

An array of six current meter moorings was deployed in the Samoan Passage (10 degrees S, 170 degrees W) from September 1992 to February 1994 with the goal of determining the northward abyssal transport. The 17-month mean transport beneath 4000 m was 6.0 Sv (10(6) m(3) s(-1)). The time series were low passed at a period of 100 hours to remove near-inertial and tidal variability, and the resulting transport had a standard deviation of 1.5 Sv, a minimum of 1.1 Sv, and a maximum of 10.7 Sv. The dominant low-frequency variability in transport and area-averaged temperature was at a period of 30 days, where the temperature led the transport as would be expected if the heat balance were advective. The temporal and spatial variability suggested that the mean transport is known to within al standard deviation error of 0.5 Sv. The along-passage flow was intensified to the west and toward the bottom as might be expected in a rotating geostrophic system. Three pathways through the sill region were identified on the basis of bathymetry and current direction. The flow was strongly controlled by topography as indicated by the flow's orientation and directional steadiness. The 30-day variability in transport might be described as a resonance of the northward abyssal flow.