This special section discusses a rare phenomenon: strong enhancement of Subarctic influence in the California Current system in the summer of 2002. This cold, fresh anomaly in the upper halocline was more extreme than any prior observation, though historical records extend back for several decades. The Subarctic anomaly extended more...
Seasonal variations in the hydrography of the waters over the continental shelf off Oregon were observed in a set of hydrographic data collected along 44º39′N at intervals of a few weeks to a few months from 1961 through 1970. The temperature is determined only partly by the local heating and...
Between April 1976 and May 1977, more than 35 repeated hydrographic sections were made just south of Cabo Nazca, Peru at 15°S, and sea level was measured continuously by a tide gage at San Juan. The sea level data were filtered to remove diurnal and shorter variations, and adjusted for...
Observations of the hydrographic regime over the continental shelf off Oregon from the R/V Yaquina during the summer of 1972 showed the presence of an alongshore, subsurface ribbon of relatively cool water. Its properties and its evolution during the 1972 season are described. Examination of earlier observations showed that evidence...
Two mesoscale surveys were conducted (in July 1981 and July 1982) near Point Arena, California, to
determine the structure and circulation associated with tongues of cold surface water extending seaward
from the coastal zone. Both surveys were designed at sea on the basis of available satellite IR data, and
each...
We investigated sea level fluctuations at seven locations from San Francisco to Torino, British
Columbia, during a 2-year period beginning in August 1973. Using overlapping 2-month periods, we
found the alongshore correlation to vary with time and with location along the coast. In winter the
fluctuatioans are correlated along the...
Repeated mesoscale surveys of a 40-km-wide, 100-km-long, coastal region near Point Arena, California, were conducted during the upwelling season (April-August) in 1981 and 1982. Each survey included conventional conductivity-temperature-depth casts at standard locations over the continental shelf and slope between 38°N and 39°10'N, and continuous operation of a Doppler acoustic...
Current and conductivity, temperature, and depth (CTD) measurements were made over the Oregon
shelf near 43°N between February 1981 and April 1984 as part of a large-scale west coast shelf experiment
(SuperCODE). The data set includes a nearly continuous record of current velocity and temperature
over the continental shelf off...
Observed changes in the nutrient levels in the halocline of the California Current during 2002 indicated a natural eutrophication that was accompanied by increased chlorophyll and oxygen in surface water. Decreased oxygen in the lower water column over the shelf indicated that much of the phytoplankton production was respired rather...
A pair of high-resolution oceanographic surveys in March and April 1995 revealed a large and rapid transition from late winter to spring conditions in the coastal zone off central and southern California. These data are unique in capturing the detailed three-dimensional physical structure of and biological response to the spring...
Repeated conductivity, temperature, and depth (CTD) sections were made across the continental
margin off Peru at 5°S and 10°S between November 1981 and May 1984, i.e., before, during, and after El
Nino of 1982-1983. Coastal sea level at Paita (5°S) and Callao (12°S) began to rise in early October 1982...
Zonal and meridional Seasoar sections centered at 1°50’S, 156°06’E were repeated >30 times in three 20-day periods between November 13, 1992, and February 15, 1993. Both sections were 130 km long, and sampling depth was 0–280 m, with a vertical resolution of ~2 dbar (2 x 104 Pa) and a...
The seasonal variation in the alongshore velocity field is inferred from direct current observations made over the Oregon continental shelf at various locations and irregular intervals since 1965. Monthly mean currents are computed and compared with earlier studies to give a description of the seasonal variation in the alongshore currents....
Horizontal wave number spectra of temperature in the unstably stratified oceanic surface layer were determined from measurements on a bow boom at a depth of 2 m. Spectra were estimated in the wavelength band from 2 m to 2 km, normalized in accordance with Monin-Obukhov similarity theory, and averaged in...
Near‐inertial motions were observed at all current meters in an array of five moorings spanning the continental margin off central Oregon during October 1977 to January 1978. All moorings were between 10 and 130 km from shore, in water depths between 100 m and 2500 m. Largest near‐inertial amplitudes (>30...
In July 1993 we collected hydrographic data and information on chlorophyll distribution on the continental shelf north of Cape Hatteras and across the shelf break at Cape Hatteras. The data show that a warm, transparent mixed layer lies over much colder, euphotic, chlorophyll-rich bottom water on the shelf. This layer...
Datasets taken near the coasts of Peru and California have been analyzed to explore the evidence of a correlation between the high frequency (period < 10.8 hour) and low frequency (period > 4 day) motions. A large part of the high frequency current is consistent with internal wave dynamics. They...
The Leeuwin Current in the Indian Ocean off Western Australia differs from the other major eastern boundary currents, e.g., California Current, since it flows rapidly poleward against the prevailing equatorward wind. The first large-scale study of the Leeuwin Current was conducted between North West Cape (22°S) and the south-western corner...
In June 1987 the geostropic flow in the coastal transition zone off northern California (between 50 and 150 km off the coast from Point Reyes to just north of Cape Mendocino) was dominated by a well-defined, southward-meandering current. Three vertical sections are presented that show the hydrographic structure of the...
Subsurface upper ocean waters off Oregon and Vancouver Island were about 1° cooler in July 2002 than in July 2001. The anomalously cool layer coincides with the permanent halocline which has salinities of 32.2 to 33.8, suggesting an invasion of nutrient-rich Subarctic waters. The anomalously cool layer lies at 30–150...
Past measurements off the coast of central Oregon and Washington have shown that the rapid change
from northward monthly mean winter winds to southward summer winds forces a "spring transition" of
the coastal ocean: sea levels and temperatures drop, and mean surface currents shift from northward to
southward. Current and...
The dynamics of the coastal transition zone off Northern California during late May and early June 1987 art
examined through assimilation modeling studies. A regional baroclinic quasi-geostrophic model is driven by the
data through initial and boundary conditions. These initial and boundary conditions are specified by objective
analysis of hydrographic...
Satellite thermal imagery and in situ biological and physical data are presented that describe the spatial variability of phytoplankton biomass and species composition in relation to the physical structure at the sea surface during persistent upwelling off northern California. Surface patterns in temperature, geostrophic velocity, chlorophyll, and particle size structure...
High concentrations of chlorophyll are found in the California Current System over
300 km offshore, far from the productive coastal upwelling region, and between 150 and
250 m, well below the depth to which photosynthetically active solar radiation penetrates.
This exceptionally deep chlorophyll feature is formed near the coast and...
Current observations over the continental shelf at locations off central Oregon and southern Washington
had the period from July 18 to September 18, 1972, in common. Low-frequency fluctuations (less than
one cycle per day) in the currents are compared by means of visual display, linear regression, and spectral
analysis. The...
Seasonal cycles of coastal wind stress, adjusted sea level (ASL), shelf currents, and water
temperatures off the west coast of North America (35°N to 48°N) are estimated by fitting annual and
semiannual harmonics to data from 1981-1983. Longer records (9-34 years) of monthly ASL indicate
that these two harmonics adequately...
Conductivity‐temperature‐depth surveys during 1988 encountered strong baroclinic jets that were evident in acoustic Doppler current profiler and hydrographic data. During June and July 1988 a filament with high surface nitrate, high chlorophyll, abundant populations of neritic centric diatoms, and higher rates of primary production was evident perpendicular to the coast...
A pair of hydrographic sections, one north and one south of Cape Blanco at 42.9N, was sampled in five summers (1998–2000 and 2002–2003). The NH line at 44.6N lies about 130 km south of the Columbia River, and spans a relatively wide shelf off Newport, Oregon. The CR line at...
During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the...
Current and conductivity, temperature, and depth (CTD) measurements were made over the Oregon
shelf near 43°N between February 1981 and April 1984 as part of a large-scale west coast shelf experiment
(SuperCODE). The data set includes a nearly continuous record of current velocity and temperature
over the continental shelf off...
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...
This report describes the state of the California Current System (CCS)—meteorological, physical, chemical, and biological—from January 2003 to the spring of 2004. The area covered in this report ranges from Oregon coastal waters to southern Baja California. Over the past year, most physical, chemical, and biological parameters were close to...
This report is the eighth in a series that describe recent oceanographic observations within the California Current system, from Oregon to Baja California. The emphasis here is placed on the observations conducted concurrently by the CalCOFI (California Cooperative Oceanic Fisheries Investigations), IMECOCAL (Investigaciones Mexicanas de la COrriente de CALifornia), and...
Knowledge of the physical oceanography of continental shelves has increased tremendously in recent years, primarily as a result of new current and hydrographic measurements made in locations where no comparable measurements existed previously. In general, observations from geographically distinct continental shelves have shown that the nature of the flow may...
Physical and biological fields in the coastal transition zone off northern California were measured during February, March, May and June 1987 in an extended alongshore region between 60 km and 150 km offshore. The spring transition, as seen in coastal sea level and winds, occurred in mid-March. Surface variability during...
This report summarizes the recent state of the California Current System (CCS), primarily during the period of April 2004 to January 2005. The report is based on observations made between Oregon and Baja California by various ocean observing programs. The CCS was not forced by any coherent basin-wide processes during...
This report summarizes physical and biological conditions in the California Current System (CCS), from Oregon to Baja California, in 2001 and 2002. The principal sources of the observations described here are the CalCOFI (California Cooperative Oceanic Fisheries Investigations), IMECOCAL (Investigaciones Mexicanas de la Corriente de California), and U.S. GLOBECLTOP (Global...
Data from the Coastal Transition Zone (CTZ) experiment are used to describe the velocity fields and water properties associate with cold filaments in the California Current. Combined with previous field surveys and satellite imagery, these show seasonal variability with maximum dynamic height ranges and velocities in summer and minimum values...
Previously published physical and biological data document a zonally oriented frontal region within the California Current system separating colder and more eutrophic water north of ≈33°N from warmer; more stratified, and oligotrophic water farther to the south. Satellite images of phytoplankton pigment from the coastal zone color scanner from 1979-1983...