Two-dimensional, primitive equation model studies of wind-forced flow over a continental shelf Show that, under upwelling conditions, high levels of near-inertial wave energy are found in the interior over the shelf. The regions of elevated wave energy, with maximum wave amplitudes of around ±0.2 m s⁻¹, persist for up to...
Sixty-day simulations of flow on the Oregon continental shelf are performed using the Blumberg and Mellor sigma coordinate, primitive equation model. The model is two-dimensional (an across-shelf section) with high spatial resolution and realistic shelf topography. Forcing consists of surface heat flux, either hourly or low-pass filtered wind stress, and...
Time-dependent upwelling on the Oregon continental shelf is studied with a two-dimensional approximation, that is, spatial variations across-shelf and with depth, using the Blumberg–Mellor, finite-difference, stratified, primitive equation model. The time-dependent response of a coastal ocean at rest to constant, upwelling favorable, wind stress is examined. Topography and stratification representative...
There is a software gap in parallel processing. The short lifespan and small installation base of parallel architectures have made it economically infeasible to develop platform-specific parallel programming environments that deliver performance and programmability. One obvious solution is to build architecture-independent programming environments. But the architecture independence usually comes at...
Influences of tidal and slower (subtidal) oceanic flows over the continental shelf and slope off Oregon are studied using a high-resolution ocean circulation model and comparative model-data analyses. The model is based on the Regional Ocean Modeling System (ROMS), a fully nonlinear, three-dimensional model (using hydrostatic and Boussinesq approximations). The...
A 1-km-horizontal-resolution model based on the Regional Ocean Modeling System is implemented along the Oregon coast to study average characteristics and intermittency of the M₂ internal tide during summer upwelling. Wind-driven and tidally driven flows are simulated in combination, using realistic bathymetry, atmospheric forcing, and boundary conditions. The study period...
A primitive equation model is used to study the finite-amplitude evolution of instabilities associated with the coastal upwelling front. Simulations of increasing complexity are examined that represent idealizations of summer conditions off the Oregon coast, including cases with steady and with time-variable wind in a domain with alongshore-uniform bathymetry and...
This study examines how coastal banks influence wind-driven circulation along stratified continental shelves. Numerical experiments are conducted for idealized symmetric banks; the standard bank (200 km long and 50 km wide) has dimensions similar to the Heceta Bank complex along the Oregon shelf. Model runs are forced with 10 days...
Internal tides on the continental shelf can be intermittent as a result of changing hydrographic conditions
associated with wind-driven upwelling. In turn, the internal tide can affect transports associated with upwelling.
To study these processes, simulations in an idealized, alongshore uniform setup are performed utilizing
the hydrostatic Regional Ocean Modeling...
A fluorescent dye tracer was injected into the
pycnocline on the Oregon shelf at a depth of 9–10 m. It
spread rapidly cross-shelf as two distinct layers, one above
the other in the water column, split by interleaving dye-free
water. The vertical scale of these layers, and associated
density steps,...
Surface heat flux components are estimated at a midshelf site over the northern California shelf using moored measurements from the 1981-1982 Coastal Ocean Dynamics Experiment (CODE) and the 1988-1989 Shelf Mixed Layer Experiment (SMILE). Time series of estimated fluxes extend from early winter through summer upwelling conditions, allowing examination of...
The linear stability of a nearly time-periodic, nonlinear, coastal upwelling–downwelling circulation, over alongshore-uniform topography, driven by a time-periodic wind stress is investigated using numerical methods. The near-periodic alongshore-uniform basic flow is obtained by forcing a primitive equation numerical model of coastal ocean circulation with periodic wind stress. Disturbance growth on...
We measured iron concentrations off the Oregon coast in spring (May–June) and summer (August) of 2001 as part of the Coastal Ocean Advances in Shelf Transport (COAST) program. Dissolvable and total dissolvable iron levels in surface waters were generally higher in spring (mean of 2.1 and 33.9 nmol L¯¹, respectively)...
In summer 1988, we made repeated mesoscale surveys of a grid extending 200 km offshore between
37°N and 39°N in the coastal transition zone off northern California, obtaining continuous acoustic
Doppler current profiler data and conductivity-temperature-depth data at standard stations 25 km apart
on alongshore sections 40 km apart. All...
A biological pump for transferring atmospheric CO₂ to deep ocean regimes has been
identified in the upwelling zone of the U.S. Pacific coast off Oregon using high-resolution
measurements of Pco₂ and nutrient concentrations that were made in May through
August 2001. Surface water over most of the shelf was a...
Air–sea coupling during coastal upwelling was examined through idealized three-dimensional numerical simulations with a coupled atmosphere–ocean mesoscale model. Geometry, topography, and initial and
boundary conditions were chosen to be representative of summertime coastal conditions off the Oregon coast. Over the 72-h simulations, sea surface temperatures were reduced several degrees near...
The sensitivity of model-produced time-dependent wind-driven circulation on the
continental shelf to the turbulent closure scheme employed is studied with a twodimensional
approximation (variations across-shelf and in depth) using the Princeton
Ocean Model. The level 2.5 Mellor-Yamada closure (MY), k-ε closure, and K-Profile
Parameterization schemes are used to evaluate the...
The behavior of three ecosystem models is analyzed for upwelling off the Oregon coast as a function of the number of model components. The first ecosystem model includes dissolved inorganic nitrogen-phytoplankton-zooplankton (NPZ), the second (NPZD) adds detritus, and the third (NNPZD) splits the nutrients into nitrate and ammonium. The models...
Detailed and repeated measurements of nitrate across the Oregon shelf, made
coincident with turbulence measurements, reveal the importance of cross-isopycnal
mixing via turbulence in providing nitrate to the upper water column. Spatial distributions
of vertical gradients and turbulent fluxes in the Oregon coastal ocean reveal variability that
could not have...
Varied observations over Oregon’s continental shelf illustrate the
beauty and complexity of geophysical flows in coastal waters. Rapid, creative, and
sometimes fortuitous sampling from ships and moorings has allowed detailed looks
at boundary layer processes, internal waves (some extremely nonlinear), and coastal
currents, including how they interact. These processes drive...