scholarly journals Essential krill species habitat resolved by seasonal upwelling and ocean circulation models within the large marine ecosystem of the California Current System

Ecography ◽  
2020 ◽  
Vol 43 (10) ◽  
pp. 1536-1549
Author(s):  
Megan A. Cimino ◽  
Jarrod A. Santora ◽  
Isaac Schroeder ◽  
William Sydeman ◽  
Michael G. Jacox ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Current System ◽  
Marine Ecosystem ◽  
California Current ◽  
California Current System ◽  
Large Marine Ecosystem

scholarly journals The California Current System in relation to the Northeast Pacific Ocean circulation

2021 ◽  
Author(s):  
Guillermo Auad
Keyword(s):  
Los Angeles ◽  
Pacific Ocean ◽  
San Francisco ◽  
Ocean Circulation ◽  
North Pacific ◽  
North Pacific Ocean ◽  
Current System ◽  
California Current ◽  
California Current System ◽  
The Mean

The California Current System is described in its regional setting using two modern datasets. Argo provides a broadscale view of the entire eastern North Pacific Ocean for the period 2004–2010, and the High Resolution XBT Network includes transects from Honolulu to San Francisco (1991–2010) and to Los Angeles (2008–2010). Together these datasets describe a California Current of 500–800 km width extending along the coast from 43°N to 23°N. The mean southward transport of the California Current is about 5 Sv off Central and Southern California, with about 2.5 Sv of northward flow on its inshore side. Interannual variations are 50% or more of the mean transports. The salinity minimum in the core of the California Current is supplied by the North Pacific Current and by freshwater from the northern continental shelf and modified by alongshore geostrophic and across-shore Ekman advection as well as eddy fluxes and air–sea exchange. The heat and freshwater content of the California Current vary in response to the fluctuating strength of the alongshore geostrophic flow. On its offshore side, the California Current is influenced by North Pacific Intermediate Waters at its deepest levels and by Eastern Subtropical Mode Waters on shallower density surfaces. In total, the sources of the California Current, its alongshore advection, and its strong interactions with the inshore upwelling region and the offshore gyre interior combine to make this a rich and diverse ecosystem. The present work reviews previous contributions to the regional oceanography, and uses the new datasets to paint a spatially and temporally more comprehensive description than was possible previously.

scholarly journals Climate-driven aerobic habitat loss in the California Current System

2020 ◽  
Vol 6 (20) ◽  
pp. eaay3188 ◽  
Author(s):  
Evan M. Howard ◽  
Justin L. Penn ◽  
Hartmut Frenzel ◽  
Brad A. Seibel ◽  
Daniele Bianchi ◽  
...  
Keyword(s):  
Habitat Loss ◽  
Current System ◽  
Marine Ecosystem ◽  
Oxygen Demand ◽  
California Current ◽  
Regional Variability ◽  
California Current System ◽  
Large Fluctuations ◽  
Northern Anchovy ◽  
Species Specific

Climate warming is expected to intensify hypoxia in the California Current System (CCS), threatening its diverse and productive marine ecosystem. We analyzed past regional variability and future changes in the Metabolic Index (Φ), a species-specific measure of the environment’s capacity to meet temperature-dependent organismal oxygen demand. Across the traits of diverse animals, Φ exhibits strong seasonal to interdecadal variations throughout the CCS, implying that resident species already experience large fluctuations in available aerobic habitat. For a key CCS species, northern anchovy, the long-term biogeographic distribution and decadal fluctuations in abundance are both highly coherent with aerobic habitat volume. Ocean warming and oxygen loss by 2100 are projected to decrease Φ below critical levels in 30 to 50% of anchovies’ present range, including complete loss of aerobic habitat—and thus likely extirpation—from the southern CCS. Aerobic habitat loss will vary widely across the traits of CCS taxa, disrupting ecological interactions throughout the region.

scholarly journals Weak constraint four-dimensional variational data assimilation in a model of the California Current System

2016 ◽  
Vol 2 (2) ◽  
pp. 171-192 ◽  
Author(s):  
William J. Crawford ◽  
Polly J. Smith ◽  
Ralph F. Milliff ◽  
Jerome Fiechter ◽  
Christopher K. Wikle ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Ocean Circulation ◽  
Hierarchical Modeling ◽  
Current System ◽  
California Current ◽  
Model Errors ◽  
Strong Constraint ◽  
California Current System ◽  
Twin Model ◽  
Error Covariance

Abstract. A new approach is explored for computing estimates of the error covariance associated with the intrinsic errors of a numerical forecast model in regions characterized by upwelling and downwelling. The approach used is based on a combination of strong constraint data assimilation, twin model experiments, linear inverse modeling, and Bayesian hierarchical modeling. The resulting model error covariance estimates Q are applied to a model of the California Current System using weak constraint four-dimensional variational (4D-Var) data assimilation to compute estimates of the ocean circulation. The results of this study show that the estimates of Q derived following our approach lead to demonstrable improvements in the model circulation estimates and isolate regions where model errors are likely to be important and that have been independently identified in the same model in previously published work.

scholarly journals A monthly surface pCO<sub>2</sub> product for the California Current Large Marine Ecosystem

2021 ◽  
Author(s):  
Jonathan D. Sharp ◽  
Andrea J. Fassbender ◽  
Brendan R. Carter ◽  
Paige D. Lavin ◽  
Adrienne J. Sutton
Keyword(s):  
Current System ◽  
Marine Ecosystem ◽  
California Current ◽  
Co2 Exchange ◽  
Coastal Ocean ◽  
California Current System ◽  
Spatial And Temporal Scales ◽  
Data Product ◽  
Spatially Resolved ◽  
Carbon Dioxide Gas

Abstract. To calculate the direction and rate of carbon dioxide gas (CO2) exchange between the ocean and atmosphere, it is critical to know the partial pressure of CO2 in surface seawater (pCO2(sw)). Over the last decade, a variety of data products of global monthly pCO2(sw) have been produced, primarily for the open ocean on 1° latitude by 1° longitude grids. More recently, monthly products of pCO2(sw) that are more finely spatially resolved in the coastal ocean have been made available. A remaining challenge in the development of pCO2(sw) products is the robust characterization of seasonal variability, especially in nearshore coastal environments. Here we present a monthly data product of pCO2(sw) at 0.25° latitude by 0.25° longitude resolution in the Northeast Pacific Ocean, centered around the California Current System (CCS). The data product (RFR-CCS; Sharp et al., 2021; https://doi.org/10.5281/zenodo.5523389) was created using the most recent (2021) version of the Surface Ocean CO2 Atlas (Bakker et al., 2016) from which pCO2(sw) observations were extracted and fit against a variety of satellite- and model-derived surface variables using a random forest regression (RFR) model. We validate RFR-CCS in multiple ways, including direct comparisons with observations from moored autonomous surface platforms, and find that the data product effectively captures seasonal pCO2(sw) cycles at nearshore mooring sites. This result is notable because alternative global products for the coastal ocean do not capture local variability effectively in this region. We briefly review the physical and biological processes — acting across a variety of spatial and temporal scales — that are responsible for the latitudinal and nearshore-to-offshore pCO2(sw) gradients seen in RFR-CCS reconstructions of pCO2(sw).

scholarly journals Reconstruction of Diffusion Coefficients and Power Exponents from Single Lagrangian Trajectories

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 111
Author(s):  
Leonid M. Ivanov ◽  
Collins A. Collins ◽  
Tetyana Margolina
Keyword(s):  
Black Sea ◽  
Diffusion Coefficients ◽  
Current System ◽  
Mean Square Displacement ◽  
California Current ◽  
The Black Sea ◽  
Mean Square ◽  
California Current System ◽  
The Mean ◽  
Non Gaussian

Using discrete wavelets, a novel technique is developed to estimate turbulent diffusion coefficients and power exponents from single Lagrangian particle trajectories. The technique differs from the classical approach (Davis (1991)’s technique) because averaging over a statistical ensemble of the mean square displacement (<X2>) is replaced by averaging along a single Lagrangian trajectory X(t) = {X(t), Y(t)}. Metzler et al. (2014) have demonstrated that for an ergodic (for example, normal diffusion) flow, the mean square displacement is <X2> = limT→∞τX2(T,s), where τX2 (T, s) = 1/(T − s) ∫0T−s(X(t+Δt) − X(t))2 dt, T and s are observational and lag times but for weak non-ergodic (such as super-diffusion and sub-diffusion) flows <X2> = limT→∞≪τX2(T,s)≫, where ≪…≫ is some additional averaging. Numerical calculations for surface drifters in the Black Sea and isobaric RAFOS floats deployed at mid depths in the California Current system demonstrated that the reconstructed diffusion coefficients were smaller than those calculated by Davis (1991)’s technique. This difference is caused by the choice of the Lagrangian mean. The technique proposed here is applied to the analysis of Lagrangian motions in the Black Sea (horizontal diffusion coefficients varied from 105 to 106 cm2/s) and for the sub-diffusion of two RAFOS floats in the California Current system where power exponents varied from 0.65 to 0.72. RAFOS float motions were found to be strongly non-ergodic and non-Gaussian.

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