Hydrographic observations made with an undulating vehicle carrying a CTD and concurrent shipboard ADCP velocity observations over a 12‐day period are combined to investigate vertical mixing and cross‐frontal fluxes on the Northern Flank of Georges Bank. The CTD density time series is analyzed to detect the presence of vertical overturns,...
Equatorward velocities in the upwelling jet of the northern California Current were 0.05–0.06 m s¯¹ faster in spring and summer 2002 than on average over 1998–2002. This result is based on a five-year data set of surface drifters released across the continental margin off central Oregon (44.65°N) during April and...
We present velocity observations from a shipboard acoustic Doppler current profiler (ADCP) on R/V Wecoma during cruise W0105c (23 May to 13 June 2001). The cruise was a component (Survey I) of the Coastal Ocean Advances in Shelf Transport (COAST) experiment. The ADCP was an RD Instruments hull-mounted 153.6-kHz narrowband...
Upwelling jets flow alongshore in approximate geostrophic balance with the onshore pressure gradient induced by coastal upwelling. Observations of such jets have shown that they often move offshore downstream of capes, leaving a pool of upwelled water inshore. Comparisons are made between this behavior and the hydraulic transition of a...
A high-resolution numerical model with idealized topography is used to investigate the degree to which a coastal upwelling jet separates from the shelf as it flows around a submarine bank depending on the wind strength and the horizontal scale of the bank. Experiments were run using several wind forcing magnitudes...
As part of the Coastal Ocean Processes (CoOP) project Coastal Ocean Advances in Shelf Transport (COAST), this was the second of two cruises in 2001 to study cross-shelf transport processes in a wind-driven coastal ocean. The project includes field experiments off the Oregon coast and coordinated ocean circulation/ecosystem and atmospheric...
MicroSoar, an undulating profiler capable of measuring turbulence parameters such as Thorpe scales and thermal dissipation rate while being towed at speeds of up to 4 m s⁻¹, offers the possibility of obtaining a close-to-synoptic image of mixing over large spatial areas. In this paper, the method of calculating Thorpe...
Several diagnoses of three-dimensional circulation, using density and velocity data from a high-resolution, upper-ocean SeaSoar and acoustic Doppler current profiler (ADCP) survey of a cyclonic jet meander and adjacent cyclonic eddy containing high Rossby number flow, are compared. The Q-vector form of the quasigeostrophic omega equation, two omega equations derived...
Recent work by S. Lentz et al. documents offshore transport in the inner shelf due to a wave-driven return
flow associated with the Hasselmann wave stress (the Stokes–Coriolis force). This analysis is extended using
observations from the central Oregon coast to identify the wave-driven return flow present and quantify the...
The event-scale variability of across-shelf transport was investigated using observations made in 15 m of
water on the central Oregon inner shelf. In a study area with intermittently upwelling-favorable winds and
significant density stratification, hydrographic and velocity observations show rapid across-shelf movement of
water masses over event time scales of...
The spatial and temporal variability of inner-shelf circulation along the central Oregon coast during the
2004 upwelling season is described using a 70-km-long array of moorings along the 15-m isobath. Circulation
at three stations located onshore of a submarine bank differed from that of a station north of the bank,...
Wind-driven coastal ocean upwelling supplies nutrients to the
euphotic zone near the coast. Nutrients fuel the growth of phytoplankton,
the base of a very productive coastal marine ecosystem
[Pauly D, Christensen V (1995) Nature 374:255–257]. Because
nutrient supply and phytoplankton biomass in shelf waters are
highly sensitive to variation in...
By mapping the three-dimensional density field while simultaneously tracking a subsurface, isopycnal float, direct observations of upwelling along a shelfbreak front were made on the southern flank of Georges Bank. The thermohaline and bio-optical fields were mapped using a towed undulating vehicle, and horizontal velocity was measured with a shipboard...
Drifters released offshore of Oregon during predominantly downwelling favorable alongshore winds during three different deployments (October 1994, January 1998, and September 1998) display similar behavior: after being advected around in the offshore eddy field, they move onshore to a particular isobath and are advected poleward alongshore, without coming ashore. Numerical...
Horizontal current measurements from an array of moored acoustic Doppler profilers are assimilated sequentially into a model of coastal wind-driven circulation off Oregon during the upwelling season of May–August 2001. Model results are compared against independent moored and ship survey data to document a positive effect of velocity data assimilation...
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,...
During the upwelling season in central California, northwesterly winds along the
coast produce a strong upwelling jet that originates at Point Año Nuevo and flows
southward across the mouth of Monterey Bay. A convergent front with a mean
temperature change of 3.77 ± 0.29°C develops between the warm interior waters...
Observations, from the Oregon continental shelf, describe the slumping of a coastal
upwelling front in response to a reversal of winds from upwelling-to downwelling-favorable.
Initially, the front outcropped in a surface mixed layer of depth 10–20 m with a
pronounced cross-shelf density gradient. Following wind reversal, both the unbalanced
cross-shelf...
During March–April 1999, 2 weeks of undulating CTD and shipboard acoustic
Doppler current profiler surveys revealed the variability of the intense internal tide on the
northern edge of Georges Bank. The nature of the internal tide was modulated by episodic
surface intrusions of cool, fresh Scotian Shelf Water (SSW), stratifying...
Velocity measurements from 17 deployments of moored acoustic Doppler current
profilers obtained during four summer upwelling seasons are used to describe the crossshelf
divergence of Ekman transport in the inner shelf off Oregon. For each deployment
the measured surface and bottom cross-shelf transports were compared with estimates
of the theoretical...