Primary production in the eastern tropical Pacific: A review   总被引：2，自引：12，他引：2  

J. Timothy Pennington  Kevin L. Mahoney  Victor S. Kuwahara  Dorota D. Kolber  Ruth Calienes  Francisco P. Chavez   《Progress in Oceanography》2006,69(2-4):285

The eastern tropical Pacific includes 28 million km² of ocean between 23.5°N and S and Central/South America and 140°W, and contains the eastern and equatorial branches of the north and South Pacific subtropical gyres plus two equatorial and two coastal countercurrents. Spatial patterns of primary production are in general determined by supply of macronutrients (nitrate, phosphate) from below the thermocline. Where the thermocline is shallow and intersects the lighted euphotic zone, biological production is enhanced. In the eastern tropical Pacific thermocline depth is controlled by three interrelated processes: a basin-scale east/west thermocline tilt, a basin-scale thermocline shoaling at the gyre margins, and local wind-driven upwelling. These processes regulate supply of nutrient-rich subsurface waters to the euphotic zone, and on their basis we have divided the eastern tropical Pacific into seven main regions. Primary production and its physical and chemical controls are described for each.Enhanced rates of macronutrient supply maintains levels of primary production in the eastern tropical Pacific above those of the oligotrophic subtropical gyres to the north and south. On the other hand lack of the micronutrient iron limits phytoplankton growth (and nitrogen fixation) over large portions of the open-ocean eastern tropical Pacific, depressing rates of primary production and resulting in the so-called high nitrate-low chlorophyll condition. Very high rates of primary production can occur in those coastal areas where both macronutrients and iron are supplied in abundance to surface waters. In these eutrophic coastal areas large phytoplankton cells dominate; conversely, in the open-ocean small cells are dominant. In a ‘shadow zone’ between the subtropical gyres with limited subsurface ventilation, enough production sinks and decays to produce anoxic and denitrified waters which spread beneath very large parts of the eastern tropical Pacific.Seasonal cycles are weak over much of the open-ocean eastern tropical Pacific, although several eutrophic coastal areas do exhibit substantial seasonality. The ENSO fluctuation, however, is an exceedingly important source of interannual variability in this region. El Niño in general results in a depressed thermocline and thus reduced rates of macronutrient supply and primary production. The multi-decadal PDO is likely also an important source of variability, with the ‘El Viejo’ phase of the PDO resulting in warmer and lower nutrient and productivity conditions similar to El Niño.On average the eastern tropical Pacific is moderately productive and, relative to Pacific and global means, its productivity and area are roughly equivalent. For example, it occupies about 18% of the Pacific Ocean by area and accounts for 22–23% of its productivity. Similarly, it occupies about 9% of the global ocean and accounts for 10% of its productivity. While representative, these average values obscure very substantial spatial and temporal variability that characterizes the dynamics of this tropical ocean.  相似文献   

Equilibrium constants of triethanolamine in major seawater salts     

I. Brandariz  P. Castro  M. Montes  F. Penedo  M.E. Sastre de Vicente 《Marine Chemistry》2006,102(3-4):291-299

Acid–base equilibrium constants of triethanolamine (TEA) have been determined by potentiometric titrations with a glass electrode, at 25 °C. Ionic strength was kept constant with only one electrolyte (using one of these salts: NaCl, KCl, MgCl₂ or CaCl₂), with binary mixtures of MgCl₂ and CaCl₂, and finally, in a solution with a composition approximately similar to that of natural seawater without sulfate. Equilibrium constants have been expressed in function of ionic strength by means of Pitzer equations and interaction parameters proposed in this theory have been obtained. It has been found that acid–base behaviour of TEA depends greatly on the salt used: basicity of TEA is decreased by CaCl₂, while it is increased by the other electrolytes used in this work.  相似文献   

Baroclinic Buoyancy-Inertia Joint Stability Parameter     

Hideo Kawai 《Journal of Oceanography》2005,61(2):235-246

At present, the barotropic buoyant stability parameter has been derived from a vertical virtual displacement of a water parcel. The barotropic inertial stability parameter in the eccentrically cyclogeostrophic, basic current field was derived in 2003 from a horizontal cross-stream virtual displacement of a parcel. By expressing acceleration of a parcel due to a virtual displacement, which is arbitrarily sloping within a vertical section across the basic current, in terms of natural coordinates, we derived the vertical component of baroclinic buoyant stability parameter B ₂ ², the horizontal component of baroclinic inertial stability parameter I ₂ ², the baroclinic joint stability parameter J ², its buoyant component B ² and its inertial component I ². B ² is far greater than I ₂ ², and when neglecting relative vorticity except for vertical shear, a downward convex curve of J ² plotted against the slope of a virtual displacement follows a trend of B ² curve. If a parcel displaces along a horizontal surface or an isopycnal surface, however, B ² vanishes, and J ² becomes equal to I ². Actual parcel is apt to displace not only along the bottom slope, but also along the sea surface and an isopycnal interfacial surface, which is approximately equivalent to an isentropic surface, preferred by lateral mixing and exchange of momentum. Such actual displacement makes B ² vanishing, and grants I ² an important role. The present analysis of I ² examining effects due to curvature and horizontal and vertical shear vorticities are useful in deepening our understanding of baroclinic instability in actual oceanic streams.  相似文献   

Preconditioned Optimizing Utility for Large-dimensional analyses (POpULar)     

Yosuke Fujii 《Journal of Oceanography》2005,61(1):167-181

I present the derivation of the Preconditioned Optimizing Utility for Large-dimensional analyses (POpULar), which is developed for adopting a non-diagonal background error covariance matrix in nonlinear variational analyses (i.e., analyses employing a non-quadratic cost function). POpULar is based on the idea of a linear preconditioned conjugate gradient method widely adopted in ocean data assimilation systems. POpULar uses the background error covariance matrix as a preconditioner without any decomposition of the matrix. This preconditioning accelerates the convergence. Moreover, the inverse of the matrix is not required. POpULar therefore allows us easily to handle the correlations among deviations of control variables (i.e., the variables which will be analyzed) from their background in nonlinear problems. In order to demonstrate the usefulness of POpULar, we illustrate two effects which are often neglected in studies of ocean data assimilation before. One is the effect of correlations among the deviations of control variables in an adjoint analysis. The other is the nonlinear effect of sea surface dynamic height calculation required when sea surface height observation is employed in a three-dimensional ocean analysis. As the results, these effects are not so small to neglect.  相似文献   

Numerical Simulation of Wind Currents and Propagation of Impurities in the Balaklava Bay     

V. V. Fomin  L. N. Repetin 《Physical Oceanography》2005,15(4):232-246

We present the results of numerical experiments aimed at the simulation of the circulation of waters and transport of impurities in the Balaklava Bay for typical wind conditions established on the basis of the analysis of the data of in-situ measurements. The currents are computed by using the nonlinear σ-coordinate model. The specific features of the integral circulation and three-dimensional structure of the current field are investigated. The statistical characteristics of currents are estimated on the basis of the in-situ data on winds and model calculations. Possible scenarios of propagation of impurities from the coastal sources are analyzed for various hydrodynamic conditions. It is shown that the localized eddy structures in the current fields (in combination with the zones of intense vertical motion) can result in a complex character of the transport of substances in the bay and lead to the formation of local regions of maximum concentrations of impurities on the boundary of the north and central parts of the bay. __________ Translated from Morskoi Gidrofizicheskii Zhurnal, No. 4, pp. 43–58, July–August, 2005.  相似文献   

Bonamia exitiosa epizootic in Ostrea chilensis from Foveaux Strait, southern New Zealand between 1986 and 1992     

Cranfield  H.J.; Dunn  A.; Doonan  I.J.; Michael  K.P. 《ICES Journal of Marine Science》2005,62(1):3-13

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Trends in biorobotic autonomous undersea vehicles   总被引：1，自引：0，他引：1  

Bandyopadhyay  P.R. 《Oceanic Engineering, IEEE Journal of》2005,30(1):109-139

The emergence of biorobotic autonomous undersea vehicle (AUV) as a focus for discipline-integrated research in the context of underwater propulsion and maneuvering is considered within the confines of the Biorobotics Program in the Office of Naval Research. The significant advances in three disciplines, namely the biology-inspired high-lift unsteady hydrodynamics, artificial muscle technology and neuroscience-based control, are discussed in an effort to integrate them into viable products. The understanding of the mechanisms of delayed stall, molecular design of artificial muscles and the neural approaches to the actuation of control surfaces is reviewed in the context of devices based on the pectoral fins of fish, while remaining focused on their integrated implementation in biorobotic AUVs. A mechanistic understanding of the balance between cruising and maneuvering in swimming animals and undersea vehicles is given. All aquatic platforms, in both nature and engineering, except during short duration burst speeds that are observed in a few species, appear to lie within the condition where their natural period of oscillation equals the time taken by them to travel the distance of their own lengths. Progress in the development of small underwater experimental biorobotic vehicles is considered where the three aforementioned disciplines are integrated into one novel maneuvering device or propulsor. The potential in maneuvering and silencing is discussed.  相似文献   

The STRATAGEM project: Stratigraphic development of the glaciated European margin   总被引：1，自引：7，他引：1  

D. Evans  M.S. Stoker  P.M. Shannon  STRATAGEM Partners 《Marine and Petroleum Geology》2005,22(9-10):969

The EC-funded STRATAGEM project ran from 2000 to 2003 and was a study of the Neogene evolution of the glaciated northeast Atlantic margin from Lofoten to Porcupine, an area extending over nearly 20 degrees of latitude. An extensive seismic, borehole and sample database has been used, much of it supplied by the oil industry. The main products of STRATAGEM have been an integrated, unified stratigraphic framework in the form of an atlas documenting and illustrating the detailed stratigraphy of the entire margin, and a detailed evolution model for this margin. A brief summary of the background to, and organisation of, the project is presented, together with an outline of the main objectives, the physiographic setting of the area and the database.  相似文献   

Storms and shoreline retreat in the southern Gulf of St. Lawrence   总被引：1，自引：0，他引：1  

Donald L. Forbes  George S. Parkes  Gavin K. Manson  Lorne A. Ketch 《Marine Geology》2004,210(1-4):169-204

Storms play a major role in shoreline recession on transgressive coasts. In the southern Gulf of St. Lawrence (GSL), southeastern Canada, long-term relative sea-level rise off the North Shore of Prince Edward Island has averaged 0.3 m/century over the past 6000 years (>0.2 m/century over 2000 years). This has driven long-term coastal retreat at mean rates >0.5 m/a but the variance and details of coastal profile response remain poorly understood. Despite extensive sandy shores, sediment supply is limited and sand is transferred landward into multidecadal to century-scale storage in coastal dunes, barrier washover deposits, and flood-tidal delta sinks. Charlottetown tide-gauge records show mean relative sea-level rise of 3.2 mm/a (0.32 m/century) since 1911. A further rise of 0.7±0.4 m is projected over the next 100 years. When differenced from tidal predictions, the water-level data provide a 90-year record of storm-surge occurrence. Combined with wind, wave hindcast, and sea-ice data, this provides a catalogue of potentially significant coastal storms. We also document coastal impacts from three recent storms of great severity in January and October 2000 and November 2001. Digital photogrammetry (1935–1990) and shore-zone surveys (1989–2001) show large spatial and temporal variance in coastal recession rates, weakly correlated with the storm record, in part because of wave suppression or coastal protection by sea ice. Large storms cause rapid erosion from which recovery depends in part on local sand supply, but barrier volume may be conserved by washover deposition. Barrier shores with dunes show high longshore and interdecadal variance, with extensive multidecadal healing of former inlet and overwash gaps. This reflects recovery from an episode of widespread overwash prior to 1935, possibly initiated by intense storms or groups of storms in the latter half of the 19th century. With evidence from the storms of 2000–2001, this points to the importance of storm clustering on scales of weeks to years in determining erosion vulnerability, as well as the need for a long-term, large-scale perspective in assessing coastal stability. The expected acceleration in relative sea-level rise, together with projections of increasing storm intensity and greatly diminished winter ice cover in the southern GSL, implies a significant increase in coastal erosion hazards in future.  相似文献   

Simulation of Hydrophysical Processes in Coastal Regions of the Sea     

Ivanov  V. A.  Kubryakov  A. I.  Lyubartseva  S. P.  Mikhailova  É. N.  Shapiro  N. B. 《Physical Oceanography》2004,14(2):67-83

In the present work, we generalize the results of our investigations in the field of simulation of hydrophysical and ecological processes in coastal regions of various seas and some closed basins. The developed and applied mathematical models and the results of numerical experiments are briefly analyzed.  相似文献