Twelve days of microstructure measurements at the equator (140°W) in November 1984 showed a
surprisingly strong effect of both daily cycle of solar heating and wind on mixing in the upper ocean.
Because of limited variations in atmospheric forcing and currents during the experiment, processes in the
daily mixing cycle...
At the smallest length scales, conductivity measurements include a contribution from salinity fluctuations in
the inertial–convective and viscous–diffusive ranges of the turbulent scalar variance spectrum. Interpreting these
measurements is complicated because conductivity is a compound quantity of both temperature and salinity.
Accurate estimates of the dissipation rate of salinity variance...
A fast-response chromel–constantan thermocouple sensor was constructed for use on the microstructure profiler Chameleon and used for 60 ocean profiles off the coast of Oregon. The stability of the thermocouple was compared to that of an FP07 microbead thermistor, and its frequency response was compared to a high-resolution microconductivity probe....
Observations of currents, hydrography, and turbulence provide unambiguous evidence for hydraulic control of flow over an isolated three-dimensional topographic feature on Oregon’s continental shelf. The flow becomes critical at the crest of the bank, forming a strong supercritical downslope flow in the lower layer. Farther downstream, internal hydraulic jumps form...
Direct determination of the irreversible turbulent flux of salinity in the ocean has not been possible because of the complexity of measuring salinity on the smallest scales over which it mixes. Presented is an analysis of turbulent salinity microstructure from measurements using a combined fast-conductivity/temperature probe on a slowly falling...
A sequence of three internal solitary waves of
elevation were observed propagating shoreward along a
near-bottom density interface over Oregon’s continental
shelf. These waves are highly turbulent and coincide with
enhanced optical backscatter, consistent with increased
suspended sediments in the bottom boundary layer. Nonlinear
solitary wave solutions are employed to...
Barotropic tidal currents flowing over rough topography may be slowed by two bottom boundary–related processes: tangential stress of the bottom boundary layer, which is generally well represented by a quadratic drag law, and normal stress from bottom pressure, known as form drag. Form drag is rarely estimated from oceanic observations...
An integrated analysis of turbulence observations from four unique instrument platforms obtained over
the Hawaiian Ridge leads to an assessment of the vertical, cross-ridge, and along-ridge structure of turbulence
dissipation rate and diffusivity. The diffusivity near the seafloor was, on average, 15 times that in the
midwater column. At 1000-m...
Since the end of the Cold War, the US Navy has had an increasing interest in continental shelves and slopes as
operational areas. To work in such areas
requires a good understanding of ocean
acoustics, coastal physical oceanography,
and, in the modern era, autonomous
underwater vehicle (AUV) operations.
Each area...
Horizontal tow measurements of internal waves are rare and have been largely supplanted in recent
decades by vertical profile measurements. Here, estimates of isotherm displacements and turbulence dissipation
rate from a towed vehicle deployed near Hawaii are presented. The displacement data are interpreted
in terms of horizontal wavenumber spectra of...