Shipboard acoustic Doppler current profiler and conductivity-temperature-de
pth data obtained during highly stratified conditions in the Hudson River e
stuary along a section of variable width and breadth are presented. The obs
ervations emphasize tidal period asymmetries in the vertical structure of c
urrent and salinity. However, these asymmetries exhibit significant along-c
hannel structure which is determined by channel morphology. During the ebb
the flow is linearly sheared, and steep halocline slopes in the vicinity of
channel contractions are maintained by momentum advection. A minimum in ve
rtical shear across the: pycnocline occurs in channel contractions. During
food the pycnocline sharpens and flattens with a middepth velocity maximum
embedded in the pycnocline which separates a stratified surface layer from
a bottom mixed layer. The along-channel structure in vertical shear is cons
istent with a lateral vorticity equation. Estimates of Richardson numbers s
uggest that vertical mixing across the pycnocline is enhanced downstream of
channel contractions.