The relationship between Pacific hake (Merluccius productus) distribution and poleward subsurface flow in the California Current System

2006 ◽  
Vol 63 (12) ◽  
pp. 2648-2659 ◽  
Author(s):  
Vera N Agostini ◽  
Robert C Francis ◽  
Anne B Hollowed ◽  
Stephen D Pierce ◽  
Chris Wilson ◽  
...  
Keyword(s):  
Large Scale ◽  
Current System ◽  
Acoustic Doppler Current Profiler ◽  
Fish Distribution ◽  
Temperature Conductivity ◽  
California Current System ◽  
Merluccius Productus ◽  
Current Profiler ◽  
Abundance And Distribution ◽  
National Marine Fisheries Service

In a search for ocean conditions potentially affecting the extent of Pacific hake (Merluccius productus) feeding migrations, we analyzed data collected in 1995 and 1998 by the National Marine Fisheries Service on abundance and distribution of hake (by echo integration), intensity and distribution of alongshore flow (from acoustic Doppler current profiler), and temperature (conductivity–temperature–depth profiles). Our results show that Pacific hake are associated with subsurface poleward flow and not a specific temperature range. Temporal and spatial patterns characterize both hake distribution and undercurrent characteristics during the two years of this study. We suggest that poleward flow in this area defines adult hake habitat, with flow properties aiding or impeding the poleward migration of the population. We conclude that although physical processes may not directly affect fish production, they may be the link between large-scale ocean–atmosphere variability and pelagic fish distribution.

Salinity Variations in the Southern California Current*

2005 ◽  
Vol 35 (8) ◽  
pp. 1421-1436 ◽  
Author(s):  
Niklas Schneider ◽  
Emanuele Di Lorenzo ◽  
Pearn P. Niiler
Keyword(s):  
Large Scale ◽  
Southern California ◽  
Current System ◽  
California Current ◽  
Southern California Bight ◽  
Small Scale ◽  
Climate Indices ◽  
California Current System ◽  
The Mean ◽  
Salinity Variations

Abstract Hydrographic observations southwestward of the Southern California Bight in the period 1937–99 show that temperature and salinity variations have very different interannual variability. Temperature varies within and above the thermocline and is correlated with climate indices of El Niño, the Pacific decadal oscillation, and local upwelling. Salinity variability is largest in the surface layers of the offshore salinity minimum and is characterized by decadal-time-scale changes. The salinity anomalies are independent of temperature, of heave of the pycnocline, and of the climate indices. Calculations demonstrate that long-shore anomalous geostrophic advection of the mean salinity gradient accumulates along the mean southward trajectory along the California Current and produces the observed salinity variations. The flow anomalies for this advective process are independent of large-scale climate indices. It is hypothesized that low-frequency variability of the California Current system results from unresolved, small-scale atmospheric forcing or from the ocean mesoscale upstream of the Southern California Bight.

scholarly journals Can we use sea surface temperature and productivity proxy records to reconstruct Ekman upwelling?

2019 ◽  
Vol 15 (6) ◽  
pp. 1985-1998
Author(s):  
Anson Cheung ◽  
Baylor Fox-Kemper ◽  
Timothy Herbert
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Large Scale ◽  
Current System ◽  
California Current ◽  
Sea Surface ◽  
California Current System ◽  
Proxy Records ◽  
Multiple Variables ◽  
Ekman Upwelling

Abstract. Marine sediments have greatly improved our understanding of the climate system, but their interpretation often assumes that certain climate mechanisms operate consistently over all timescales of interest and that variability at one or a few sample sites is representative of an oceanographic province. In this study, we test these assumptions using modern observations in an idealized manner mimicking paleo-reconstruction to investigate whether sea surface temperature and productivity proxy records in the Southern California Current System can be used to reconstruct Ekman upwelling. The method uses extended empirical orthogonal function (EEOF) analysis of the covariation of alongshore wind stress, chlorophyll, and sea surface temperature as measured by satellites from 2002 to 2009. We find that EEOF1 does not reflect an Ekman upwelling pattern but instead much broader California Current processes. EEOF2 and 3 reflect upwelling patterns, but these patterns are timescale dependent and regional. Thus, the skill of using one site to reconstruct the large-scale dominant patterns is spatially dependent. Lastly, we show that using multiple sites and/or multiple variables generally improves field reconstruction. These results together suggest that caution is needed when attempting to extrapolate mechanisms that may be important on seasonal timescales (e.g., Ekman upwelling) to deeper time but also the advantage of having multiple proxy records.

Comparisons within and between years resulting in contrasting recruitment of Pacific hake (Merluccius productus) in the California Current System

2000 ◽  
Vol 57 (7) ◽  
pp. 1434-1447 ◽  
Author(s):  
Michael M Mullin ◽  
Erica Goetze ◽  
Stace E Beaulieu ◽  
Jacqueline M Lasker
Keyword(s):  
Overall Survival ◽  
Current System ◽  
Survival Rates ◽  
California Current ◽  
Ekman Transport ◽  
California Current System ◽  
Merluccius Productus ◽  
The Difference ◽  
Simple Ratio ◽  
Overall Survival Rates

In a search for correlates and possible causes of the difference in recruitment success of Pacific hake (Merluccius productus) of the 1981 and 1984 year-classes, we analyzed (by optical plankton counter) the distribution into sizes of preserved zooplankton samples from stations with and without larval hake in winter and spring of these two years. We also assessed the onshore/offshore distributions of larvae, potential for geostrophic and Ekman transport, and their overall survival rates. Cluster analyses of biovolume spectra led to the development of a simple ratio of "medium" to "small + large" zooplankton that statistically separated stations within a year where larval hake were likely to be found from those where they were unlikely to be found. This biovolume ratio was independent of temperature, and the same ratio statistically distinguished stations where larval hake tended to occur in spring 1998. However, we found no property or process that might explain why the 1984 year-class was spectacularly successful.

Large Eddy Simulation of the Flow Field in the Hudson River

2011 ◽  
Author(s):  
Tuy N. M. Phan ◽  
John C. Wells ◽  
William D. Kirkey ◽  
Mohammad S. Islam ◽  
James S. Bonner
Keyword(s):  
New York ◽  
Large Eddy Simulation ◽  
Large Scale ◽  
Acoustic Doppler Current Profiler ◽  
Hudson River ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Current Profiler ◽  
Simulation Results ◽  
Indian Point

Large-eddy simulation (LES) has been conducted under idealized conditions in two river reaches of the Hudson River (New York, USA), with near-bank resolution set to some 5 meters in order to resolve large-scale motions of turbulence in the near-bank regions. To simplify analysis, simulation is performed at a constant discharge corresponding to a typical ebb tide. A standard Smagorinsky model is implemented in the commercial package FLUENT, with buoyancy neglected and bottom roughness set to zero. We perform Proper Orthogonal Decomposition (POD) on the LES results. POD modes are orthogonal flow fields that capture the kinetic energy in an optimally convergent fashion. Results show that only a few POD modes are enough to describe the most energetic flow dynamics. In a reach around the Indian Point power plant, the second and third modes reflect an interesting generation of separating eddies on the western bank, which we do not find with a URANS (standard k-ε) computation on the same grid. To test our simulation, a comparison of simulation results with other simulation results and Acoustic Doppler Current Profiler (ADCP) data measured at West Point, New York will be presented.

Corrigendum to “Large-scale bloom of Akashiwo sanguinea in the Northern California current system in 2009” [Harmful Algae 37 (2014) 38–46]

Harmful Algae ◽  
2015 ◽  
Vol 44 ◽  
pp. 63
Author(s):  
Angelicque E. White ◽  
Katie S. Watkins-Brandt ◽  
S. Morgaine McKibben ◽  
A. Michelle Wood ◽  
Matthew Hunter ◽  
...  
Keyword(s):  
Large Scale ◽  
Current System ◽  
California Current ◽  
Harmful Algae ◽  
Northern California ◽  
California Current System ◽  
Northern California Current ◽  
Akashiwo Sanguinea

Large-scale bloom of Akashiwo sanguinea in the Northern California current system in 2009

Harmful Algae ◽  
2014 ◽  
Vol 37 ◽  
pp. 38-46 ◽  
Author(s):  
Angelicque E. White ◽  
Katie S. Watkins-Brandt ◽  
S. Morgaine McKibben ◽  
A. Michelle Wood ◽  
Matthew Hunter ◽  
...  
Keyword(s):  
Large Scale ◽  
Current System ◽  
California Current ◽  
Northern California ◽  
California Current System ◽  
Northern California Current ◽  
Akashiwo Sanguinea

scholarly journals Large-Scale Structure in Wind Forcing over the California Current System in Summer

2017 ◽  
Vol 145 (10) ◽  
pp. 4227-4247 ◽  
Author(s):  
Melanie R. Fewings
Keyword(s):  
Wind Velocity ◽  
Time Scales ◽  
Large Scale ◽  
Current System ◽  
California Current ◽  
Large Scale Structure ◽  
Scale Structure ◽  
California Current System ◽  
The North ◽  
North And South

The wind that drives oceanic eastern boundary upwelling systems is highly variable. In many locations, the standard deviation of wind velocity on time scales of days to weeks is larger than the mean. In the ~1600-km-long California Current System (CCS), the spatial decorrelation scale of the wind fluctuations is ~400–800 km, suggesting wind fluctuations in the north and south ends of the system are not related. Yet, there is also the suggestion in the literature of a larger-scale structure in the fluctuations. Here, empirical orthogonal function (EOF) analysis of buoy and satellite wind velocities confirms the existence of that structure. This analysis covers a larger spatial domain than previous EOF studies in the CCS and, to allow for propagation of the wind fluctuations, includes an approach for calculating Hilbert EOFs from time series with gaps. The large-scale structure in the wind fluctuations is a quasi-dipole pattern spanning the coastline from Washington through California. It accounts for ~60% of the wind velocity variance on time scales of days to weeks. The time-mean wind velocity, showing a continuous zone of intensified wind along the coast, is deceptive. When the northern half of the CCS is in a relaxation state, the southern half often experiences intensified winds, and vice versa. There should be a resulting out-of-phase structure in oceanic upwelling. The out-of-phase wind fluctuations in the north and south parts of the CCS may affect the forcing of oceanic coastal-trapped waves, mesoscale eddy generation at capes, and offshore export of carbon.

scholarly journals Offshore transport of particulate organic carbon in the California Current System by mesoscale eddies

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Caitlin M. Amos ◽  
Renato M. Castelao ◽  
Patricia M. Medeiros
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Coastal Water ◽  
Large Scale ◽  
Current System ◽  
Mesoscale Eddy ◽  
California Current ◽  
California Current System ◽  
Upwelled Water ◽  
Offshore Transport

Abstract The California Current System is characterized by upwelling and rich mesoscale eddy activity. Cyclonic eddies generally pinch off from meanders in the California Current, potentially trapping upwelled water along the coast and transporting it offshore. Here, we use satellite-derived measurements of particulate organic carbon (POC) as a tracer of coastal water to show that cyclones located offshore that were generated near the coast contain higher carbon concentrations in their interior than cyclones of the same amplitude generated offshore. This indicates that eddies are in fact trapping and transporting coastal water offshore, resulting in an offshore POC enrichment of 20.9 ± 11 Gg year−1. This POC enrichment due to the coastally-generated eddies extends for 1000 km from shore. This analysis provides large-scale observational-based evidence that eddies play a quantitatively important role in the offshore transport of coastal water, substantially widening the area influenced by highly productive upwelled waters in the California Current System.

Sign in / Sign up

Export Citation Format

Share Document