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• 11. [Article] Observations of the coastal upwelling region off Oregon during 1972

  Observations of wind, currents, sea level and hydrography obtained during the 1972 Coastal Upwelling Experiment (CUE-I) are described. Only phenomena with periods longer than a day are considered. One ...

  Citation × Citation Citation Abstract Copy Title: Observations of the coastal upwelling region off Oregon during 1972 Author: Huyer, Adriana, 1945- Observations of wind, currents, sea level and hydrography obtained during the 1972 Coastal Upwelling Experiment (CUE-I) are described. Only phenomena with periods longer than a day are considered. One section describes the changes observed during a period of variable winds in early July 1972. Another describes a ribbon of relatively cool water observed early in the upwelling season and attributes its existence to advection of Subarctic water by the coastal jet associated with upwelling. A third section describes the seasonal development of the upwelling regime between April and October 1972. These studies are combined with other studies of CUE-I data to provide a partial description of the upwelling regime which is compared to the conceptual model developed prior to CUE-I. It is concluded that the vertical and onshore velocity fields are as yet largely unknown. The alongshore velocity field includes southward surface flow with a coastal jet, a persistent vertical shear with deeper velocities northward relative to the surface and high coherence with the wind and sea level at periods of several days. A poleward undercurrent is observed, but it may not be an integral part of the upwelling regime. The hydrography has a strong seasonal cycle. Differences between any two sections between April and October l972 are smaller than between any of these and a section occupied in January 1973. Oscillations in the wind with periods of several days cause significant changes in the region inshore of 10 km and in the upper 20 m further offshore. Subsurface temperature observations are not coherent with the wind at periods of several days. Title: Observations of the coastal upwelling region off Oregon during 1972 Author: Huyer, Adriana, 1945- Observations of wind, currents, sea level and hydrography obtained during the 1972 Coastal Upwelling Experiment (CUE-I) are described. Only phenomena with periods longer than a day are considered. One section describes the changes observed during a period of variable winds in early July 1972. Another describes a ribbon of relatively cool water observed early in the upwelling season and attributes its existence to advection of Subarctic water by the coastal jet associated with upwelling. A third section describes the seasonal development of the upwelling regime between April and October 1972. These studies are combined with other studies of CUE-I data to provide a partial description of the upwelling regime which is compared to the conceptual model developed prior to CUE-I. It is concluded that the vertical and onshore velocity fields are as yet largely unknown. The alongshore velocity field includes southward surface flow with a coastal jet, a persistent vertical shear with deeper velocities northward relative to the surface and high coherence with the wind and sea level at periods of several days. A poleward undercurrent is observed, but it may not be an integral part of the upwelling regime. The hydrography has a strong seasonal cycle. Differences between any two sections between April and October l972 are smaller than between any of these and a section occupied in January 1973. Oscillations in the wind with periods of several days cause significant changes in the region inshore of 10 km and in the upper 20 m further offshore. Subsurface temperature observations are not coherent with the wind at periods of several days. Close

• 12. [Article] The nature of the cold filaments in the California current system

  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 ...

  Citation × Citation Citation Abstract Copy Title: The nature of the cold filaments in the California current system Author: Mackas, D. L., Swenson, M., Chavez, F., James, C., Batteen, M., Strub, P. Ted, Kadko, D., Abbott, Mark R., Hayward, T., Dewey, R., Ramp, S., Brink, K. H., Niiler, Pearn P., Huyer, Adriana, 1945-, Kosro, P. Michael, 1951-, Haidvogel, D., Barber, R., Haney, R., Walstad, L., Hood, R. R., Barth, John A., Washburn, L. A. 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 in late winter and early spring. North of Point Arenda (between 39ºN and 42ºN) in spring–summer the flow field on the outer edge of the cold water has the character of a meandering jet, carrying fresh, nutrient-poor water from farther north on its offshore side and cold, salty, nutrient-rich water on its inshore side. At Point Arena in midsummer, the jet often flows offshore and continues south without meandering back onshore as strongly as it does farther north. The flow field south of Point Arena in summer takes on more of the character of a field of mesoscale eddies, although the meandering jet from the north continues to be identifiable. The conceptual model for the May–July period between 36ºN and 42ºN is thus of a surface jet that meanders through and interacts with a field of eddies; the eddies are more dominant south of 39ºN, where the jet broadens and where multiple jets and filaments are often present. At the surface, the jet often separates biological communities and may appear as a barrier to cross-jet transport, especially north of Point Arena early in the season (March–May) However, phytoplankton pigment and nutrients are carried on the inshore flank of the jet, and pigment maxima are sometimes found in the core of the jet. The biological effect of the jet is to define a convoluted, 100 to 400-km-wide region next to the coast, within which much of the richer water is contained, and also to carry some of that richer water offshore in meanders along the outer edge of that region. Title: The nature of the cold filaments in the California current system Author: Mackas, D. L., Swenson, M., Chavez, F., James, C., Batteen, M., Strub, P. Ted, Kadko, D., Abbott, Mark R., Hayward, T., Dewey, R., Ramp, S., Brink, K. H., Niiler, Pearn P., Huyer, Adriana, 1945-, Kosro, P. Michael, 1951-, Haidvogel, D., Barber, R., Haney, R., Walstad, L., Hood, R. R., Barth, John A., Washburn, L. A. 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 in late winter and early spring. North of Point Arenda (between 39ºN and 42ºN) in spring–summer the flow field on the outer edge of the cold water has the character of a meandering jet, carrying fresh, nutrient-poor water from farther north on its offshore side and cold, salty, nutrient-rich water on its inshore side. At Point Arena in midsummer, the jet often flows offshore and continues south without meandering back onshore as strongly as it does farther north. The flow field south of Point Arena in summer takes on more of the character of a field of mesoscale eddies, although the meandering jet from the north continues to be identifiable. The conceptual model for the May–July period between 36ºN and 42ºN is thus of a surface jet that meanders through and interacts with a field of eddies; the eddies are more dominant south of 39ºN, where the jet broadens and where multiple jets and filaments are often present. At the surface, the jet often separates biological communities and may appear as a barrier to cross-jet transport, especially north of Point Arena early in the season (March–May) However, phytoplankton pigment and nutrients are carried on the inshore flank of the jet, and pigment maxima are sometimes found in the core of the jet. The biological effect of the jet is to define a convoluted, 100 to 400-km-wide region next to the coast, within which much of the richer water is contained, and also to carry some of that richer water offshore in meanders along the outer edge of that region. Close

• 13. [Article] Preface to special section on enhanced Subarctic influence in the California Current, 2002

  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 ...

  Citation × Citation Citation Abstract Copy Title: Preface to special section on enhanced Subarctic influence in the California Current, 2002 Author: Huyer, Adriana, 1945- 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 than 1500 km along the U. S. west coast, from 49°N to 33°N. It brought high-nutrient waters into the coastal upwelling zone off Oregon and northern California, and produced exceptionally high chlorophyll concentrations. Inner shelf oxygen concentrations were very high near the surface and very low near the bottom. The presence of this Subarctic water mass was associated with anomalous southward currents detected by three different methods: by satellite-tracked drifters, a mid-shelf mooring, and by satellite altimetry. Large-scale wind forcing over the northeastern Pacific during the previous winter and spring seems to be responsible for these anomalies. Title: Preface to special section on enhanced Subarctic influence in the California Current, 2002 Author: Huyer, Adriana, 1945- 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 than 1500 km along the U. S. west coast, from 49°N to 33°N. It brought high-nutrient waters into the coastal upwelling zone off Oregon and northern California, and produced exceptionally high chlorophyll concentrations. Inner shelf oxygen concentrations were very high near the surface and very low near the bottom. The presence of this Subarctic water mass was associated with anomalous southward currents detected by three different methods: by satellite-tracked drifters, a mid-shelf mooring, and by satellite altimetry. Large-scale wind forcing over the northeastern Pacific during the previous winter and spring seems to be responsible for these anomalies. Close

• 14. [Article] Phytoplankton and photosynthetic light response in the coastal transition zone off northern California in June 1987

  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, ...

  Citation × Citation Citation Abstract Copy Title: Phytoplankton and photosynthetic light response in the coastal transition zone off northern California in June 1987 Author: Abbott, Mark R., Hood, R. R., Huyer, Adriana, 1945- 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 current down to 100 m and its relationship to the distribution of phytoplankton biomass. The sections show that the geostrophic adjustment brought cold, saline, deep water up to the surface on the low steric height, or cold side of the flow, and that this upwelled water supported a relatively large diatom biomass (chlorophyll-a concentrations between 1 and 10 mg m-3). We present particle size spectra and photomicrographs of the phytoplankton that show that the diatom biomass was dominated by chain-forming species (e.g., Skeletonema costatum, Chaetoceros spp., Thalassiosira spp., and Rhizosolenia alata, but also a single-celled Actinocyclus sp.). Photosynthetic light response measurements reveal that these diatom communities were capable of high photosynthetic rates (Pmax between 5 and 25 mg C mg Chla-1 h-1). Although most of the diatoms were located in cold, slow-moving water on the low side of the current, some were being carried downstream. High chlorophyll concentrations were observed at depths > 75 m in and along the cold edge of the flow in all of our sections; we show evidence that in tow out of three cases this was the result of water mass subduction. Title: Phytoplankton and photosynthetic light response in the coastal transition zone off northern California in June 1987 Author: Abbott, Mark R., Hood, R. R., Huyer, Adriana, 1945- 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 current down to 100 m and its relationship to the distribution of phytoplankton biomass. The sections show that the geostrophic adjustment brought cold, saline, deep water up to the surface on the low steric height, or cold side of the flow, and that this upwelled water supported a relatively large diatom biomass (chlorophyll-a concentrations between 1 and 10 mg m-3). We present particle size spectra and photomicrographs of the phytoplankton that show that the diatom biomass was dominated by chain-forming species (e.g., Skeletonema costatum, Chaetoceros spp., Thalassiosira spp., and Rhizosolenia alata, but also a single-celled Actinocyclus sp.). Photosynthetic light response measurements reveal that these diatom communities were capable of high photosynthetic rates (Pmax between 5 and 25 mg C mg Chla-1 h-1). Although most of the diatoms were located in cold, slow-moving water on the low side of the current, some were being carried downstream. High chlorophyll concentrations were observed at depths > 75 m in and along the cold edge of the flow in all of our sections; we show evidence that in tow out of three cases this was the result of water mass subduction. Close

• 15. [Article] Near-inertial motions off the Oregon Coast

  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 ...

  Citation × Citation Citation Abstract Copy Title: Near-inertial motions off the Oregon Coast Author: Smith, Robert L. (Robert Lloyd), 1935, Anderson, Lain, Huyer, Adriana, 1945- 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 cm/s) were observed at the uppermost current meters of the offshore moorings, although these were below the surface mixed layer. The near-inertial energy generally decreased with increasing depth, and there was less near-inertial energy over the continental shelf than at similar depths offshore. The energy levels observed over the shelf were about the same as observed there during summer 1973, and the energy levels observed offshore were comparable with those observed in the open North Atlantic. Horizontal coherence scales were large, exceeding 115km during the first half of the observational period and about 60 km during the second half; estimates of the horizontal wavelength (50 km during the first half and 20 km during the second half suggest that the coherence scale is of the order of three wavelengths. Although we did not have current data in the surface mixed layer nor wind measurements over each mooring, the available meteorological data (synoptic pressure charts and hourly wind and pressure at Newport) suggest that most of the near-inertial energy was forced by the local wind. Title: Near-inertial motions off the Oregon Coast Author: Smith, Robert L. (Robert Lloyd), 1935, Anderson, Lain, Huyer, Adriana, 1945- 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 cm/s) were observed at the uppermost current meters of the offshore moorings, although these were below the surface mixed layer. The near-inertial energy generally decreased with increasing depth, and there was less near-inertial energy over the continental shelf than at similar depths offshore. The energy levels observed over the shelf were about the same as observed there during summer 1973, and the energy levels observed offshore were comparable with those observed in the open North Atlantic. Horizontal coherence scales were large, exceeding 115km during the first half of the observational period and about 60 km during the second half; estimates of the horizontal wavelength (50 km during the first half and 20 km during the second half suggest that the coherence scale is of the order of three wavelengths. Although we did not have current data in the surface mixed layer nor wind measurements over each mooring, the available meteorological data (synoptic pressure charts and hourly wind and pressure at Newport) suggest that most of the near-inertial energy was forced by the local wind. Close

• 16. [Article] Currents and water masses of the coastal transition zone off Northern California, June to August 1988

  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 ...

  Citation × Citation Citation Abstract Copy Title: Currents and water masses of the coastal transition zone off Northern California, June to August 1988 Author: Ramp, Steven R., Washburn, Libe, Cowles, Timothy J., Fleischbein, Jane, Stanton, Tim, Huyer, Adriana, 1945-, Kosro, P. Michael, 1951-, Smith, Robert L. (Robert Lloyd), 1935-, Pierce, Stephen D., Chavez, Francisco P. 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 surveys showed a baroclinic equatorward jet, with core velocities of >50 cm/s at the surface decreasing to about 10 cm/s at 200m , a width of 50-75 km, and a baroclinic transporotf about4 Sv. The core of the jet lay between the 8.6 and9 .4 m²/s² contours of geopotential anomaly (relative to 500 dbar). Three current meter moorings, deployed at 25-km separation across the jet at the beginning of the survey sequence, provided time-series of the velocity; throughout the 37-day deployment, at least one mooring was within the core defined by the 8.6 and9 .4 m²/s² contours. The jet flowed southwestward across the grid from late June until mid-July 1988, when the jet axis moved offshore in the north and onshore in the southern portion of the grid. Temperature-salinity analysis shows that jet waters can be distinguished from both the freshly upwelled coastal waters and the offshore waters. Isopycnal maps indicate alongshore advection of relatively fresh, cool water from farther north, as well as small-scale patchiness not resolved by our survey grid. The baroclinic jet observed here may be continuous with the core of the California Current off central California. The later surveys clearly showed a poleward-flowing undercurrent adjacent to the continental slope, with core velocities up to 20 cm/s at depths of 150-250 m. Its baroclinic transport (relative to 500 dbar) increased from <0.5 Sv to >1.0 Sv between late June and early August 1988. Within the survey grid, there was a definite onshore gradient in the characteristics of North Pacific Intermediate Water. The subsurface waters adjacent to the continental margin were warmer and more saline than those offshore, indicating net northward advection by the California Undercurrent over the inshore 100 km and equatorward advection farther from shore. Title: Currents and water masses of the coastal transition zone off Northern California, June to August 1988 Author: Ramp, Steven R., Washburn, Libe, Cowles, Timothy J., Fleischbein, Jane, Stanton, Tim, Huyer, Adriana, 1945-, Kosro, P. Michael, 1951-, Smith, Robert L. (Robert Lloyd), 1935-, Pierce, Stephen D., Chavez, Francisco P. 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 surveys showed a baroclinic equatorward jet, with core velocities of >50 cm/s at the surface decreasing to about 10 cm/s at 200m , a width of 50-75 km, and a baroclinic transporotf about4 Sv. The core of the jet lay between the 8.6 and9 .4 m²/s² contours of geopotential anomaly (relative to 500 dbar). Three current meter moorings, deployed at 25-km separation across the jet at the beginning of the survey sequence, provided time-series of the velocity; throughout the 37-day deployment, at least one mooring was within the core defined by the 8.6 and9 .4 m²/s² contours. The jet flowed southwestward across the grid from late June until mid-July 1988, when the jet axis moved offshore in the north and onshore in the southern portion of the grid. Temperature-salinity analysis shows that jet waters can be distinguished from both the freshly upwelled coastal waters and the offshore waters. Isopycnal maps indicate alongshore advection of relatively fresh, cool water from farther north, as well as small-scale patchiness not resolved by our survey grid. The baroclinic jet observed here may be continuous with the core of the California Current off central California. The later surveys clearly showed a poleward-flowing undercurrent adjacent to the continental slope, with core velocities up to 20 cm/s at depths of 150-250 m. Its baroclinic transport (relative to 500 dbar) increased from <0.5 Sv to >1.0 Sv between late June and early August 1988. Within the survey grid, there was a definite onshore gradient in the characteristics of North Pacific Intermediate Water. The subsurface waters adjacent to the continental margin were warmer and more saline than those offshore, indicating net northward advection by the California Undercurrent over the inshore 100 km and equatorward advection farther from shore. Close