Sea surface temperature (SST) is a critical control on the atmosphere(1), and numerical models of atmosphere-ocean circulation emphasize its accurate prediction. Yet many models demonstrate large, systematic biases in simulated SST in the equatorial 'cold tongues' (expansive regions of net heat uptake from the atmosphere) of the Atlantic(2) and Pacific(3)...
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...
Directly wind-coherent near-inertial surface currents off the Oregon coast are investigated with a statistical parameterization of observations and outputs of a regional numerical ocean model and three one-dimensional analytical models including the slab layer, Ekman, and near-surface averaged Ekman models. The
transfer functions and response functions, statistically estimated from observed...
In this study, uncoupled and coupled ocean–atmosphere simulations are carried out for the California Upwelling System to assess the dynamic ocean–atmosphere interactions, namely, the ocean surface current feedback to the atmosphere. The authors show the current feedback, by modulating the energy transfer from the atmosphere to the ocean, controls the...
A single nonlinear internal wave tracked more than 100 wavelengths across Oregon’s continental shelf over a 12-h period exhibited nearly constant wave speed, c = 0.75 m s⁻¹, and amplitude, a = 15 m. The wavelength L gradually decreased from 220 m in 170-m water depth to 60 m in...
A low-power (<10 mW), physically small (15.6 cm long × 3.2 cm diameter), lightweight (600 g Cu; alternatively, 200 g Al), robust, and simply calibrated pitot-static tube to measure mean speed and turbulence dissipation (ε ) is described and evaluated. The measurement of speed is derived from differential pressure via...
Results from a model of wind-driven circulation are analyzed to study spatial and temporal variability in
the bottom mixed layer (BML) on the mid-Oregon shelf in summer 2001. The model assimilates acoustic
Doppler profiler velocities from two cross-shore lines of moorings 90 km apart to provide improved
accuracy of near-bottom...
Comprehensive observations of velocity, density, and
turbulent dissipation permit quantification of the nonlinear
internal wave (NLIW) contribution to vertical heat flux and
lateral mass transport over New Jersey’s shelf. The effect of
NLIWs on the shelf heat budget was significant. On
average, heat flux in NLIWs was 10 times larger...
Regional ocean circulation along the Oregon coast is studied numerically for forcing fields derived from year 2005 and climatological-mean conditions. The primary object is to study directly the Lagrangian pathways by which fluid arrives in the Oregon upwelling zone. Roughly half of the upwelling fluid is found to arrive in...
Extended measurements of temperature fluctuations that include the turbulence wavenumber band have now been made using rapidly sampled fast thermistors at multiple depths above the core of the Equatorial Undercurrent on the Tropical Atmosphere Ocean (TAO) mooring at 0°, 140°W. These measurements include the signature of narrowband oscillations as well...
A new theory of shear instability in a turbulent environment is applied to eight days of velocity and density profiles from the upper-equatorial Pacific. This period featured a regular diurnal cycle of surface forcing, together with a clear response in upper-ocean mixing. During the day, a layer of stable stratification...
Strong modulation of turbulent mixing by a westward-propagating tropical instability wave (TIW) was observed in the stratified shear layer between the equatorial undercurrent (EUC) and the surface mixed layer during October and November 2008 at 0°N 140°W. The unique deep diurnal-cycle mixing in the stratified layer beneath the equatorial cold...
Observations off the New Jersey coast document the shoaling of three groups of nonlinear internal waves of depression over 35 km across the shelf. Each wave group experienced changing background conditions along its shoreward transit. Despite different wave environments, a clear pattern emerges. Nearly symmetric waves propagating into shallow water...
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...
Packets of nonlinear internal waves (NLIWs) in a small area of the Mid-Atlantic Bight were 10 times more energetic during a local neap tide than during the preceding spring tide. This counterintuitive result cannot be explained if the waves are generated near the shelf break by the local barotropic tide...
As currents flow over rough topography, the pressure difference between the up-and downstream sides results in form drag-a force that opposes the flow. Measuring form drag is valuable because it can be used to estimate the loss of energy from currents as they interact with topography. An array of bottom...
Ship and mooring data collected off the coast of New Jersey are used to describe the nonlinear internal wave (NLIW) field and the background oceanographic conditions that formed the waveguide on the shelf. The subinertial, inertial, and tidal circulation are described in detail, and the background fluid state is characterized...
We use density and microstructure data to characterize the properties and physical setting of optical thin layers observed over the New Jersey shelf in the summer of 2006. Layers were differentiated into two types by their vertical position in the water column, fluorescence intensity, and possibly community composition or cell...
Shoreward propagating, mode 2 nonlinear waves appear sporadically in mooring records obtained off the coast of New Jersey in the summer of 2006. Individual mode 2 packets were tracked between two moorings separated by 1 km; however, packets could not be tracked between moorings separated by greater distances from one...
Measurements of currents and turbulence beneath a geostationary ship in the equatorial Indian Ocean during a period of weak surface forcing revealed unexpectedly strong turbulence beneath the surface mixed layer. Coincident with the turbulence was a marked reduction of the current speeds registered by shipboard Doppler current profilers, and an...
Shipboard current measurements in the equatorial Indian Ocean in October and November of 2011 revealed oscillations in the meridional velocity with amplitude ~0.10 m/s. These were clearest in a layer extending from ~300 to 600 m depth and had periods near 3 weeks. Phase propagation was upward. Measurements from two...
Observations of mixing over the continental slope using a towed body reveal a great lateral extent (several kilometers) of continuously turbulent fluid within a few hundred meters of the boundary at depth 1600 m. The largest turbulent dissipation rates were observed over a 5 km horizontal region near a slope...
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...
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...