Eddies in Marine Science

ISBN-13: 9783642690051 / Angielski / Miękka / 2011 / 612 str.

A. R. Robinson

Opis

It is now well known that the mid-ocean flow is almost everywhere domi nated by so-called synoptic or meso-scale eddies, rotating about nearly vertical axes and extending throughout the water column. A typical mid ocean horizontal scale is 100 km and a time scale is 100 days: these meso scale eddies have swirl speeds of order 10 cm s -1 which are usually con siderably greater than the long-term average flow. Many types of eddies with somewhat different scales and characteristics have been identified. The existence of such eddies was suspected by navigators more than a century ago and confirmed by the world of C. O'D. Iselin and V. B. Stock man in the 1930's. Measurements from RIV Aries in 1959/60, using the then newly developed neutrally buoyant floats, indicated the main char acteristics of the eddies in the deep ocean of the NW Atlantic while a se ries of Soviet moored current-meter arrays culminated, in POLYGON- 1970, in the explicit mapping of an energetic anticyclonic eddy in the tropical NE Atlantic. In 1973 a large collaborative (mainly U. S., U. K. ) program, MODE-I, produced synoptic charts for an area of the NW At lantic and confirmed the existence of an open ocean eddy field and es tablished its characteristics. Meso-scale eddies are now known to be of interest and importance to marine chemists and biologists as well as to physical oceanographers and meteorologists."

Spis treści

1. Overview and Summary of Eddy Science.- 1.1 Eddy Currents in the Ocean.- 1.1.1 Observing the Eddies.- 1.1.2 Modeling the Eddies.- 1.2 Status of Eddy Science.- 1.2.1 Distribution and Generation.- 1.2.2 Physics.- 1.2.3 Role in the General Circulation.- 1.3 Influences of Eddies.- 1.3.1 Scientific Processes and Practical Consequences.- 1.3.2 Dispersion and Mixing.- 1.3.3 Description and Prediction.- 1.4 Evolution and Outlook.- 1.4.1 A Time of Transition.- 1.4.2 A Decade of Eddy Research.- 1.4.3 Eddies in Marine Science.- Regional Kinematics, Dynamics, and Statistics.- 2. Gulf Stream Rings.- 2.1 Introduction.- 2.2 History.- 2.3 Cold-Core Rings.- 2.3.1 Formation.- 2.3.2 Structure and Velocity.- 2.3.3 Distribution and number.- 2.3.4 Movement.- 2.3.5 Interaction and Coalescence with Gulf Stream.- 2.3.6 Decay.- 2.4 Warm-Core Rings.- 2.5 Gulf of Mexico Rings.- 2.6 Eastern Rings.- 2.7 Current Rings from Other Currents.- 3. Western North Atlantic Interior.- 3.1 Introduction.- 3.2 Observations.- 3.2.1 Spectrum and Time Scales.- 3.2.2 Spatial Scales.- 3.2.3 Kinetic and Potential Energy.- 3.3 Other Data.- 3.4 Some Simple Conclusions.- 4. The Western North Atlantic - A Lagrangian Viewpoint.- 4.1 Introduction.- 4.2 The Data Base.- 4.3 The Mean Field.- 4.3.1 The Lagrangian View.- 4.3.2 The Equivalent Eulerian View, and the Eddy Kinetic Energy Distribution.- 4.4 Mixing and Dispersion.- 4.5 Topographic Influences.- 4.6 The Eastward Flow in the Subtropical Gyre.- 4.7 Discrete Eddies.- 4.8 The Path of the Gulf Stream.- 4.9 Concluding Remarks.- 5. The Local Dynamics of Eddies in the Western North Atlantic.- 5.1 Introduction.- 5.2 Scientific Objectives.- 5.2.1 Dynamical Balances.- 5.2.2 Synoptic Structures.- 5.2.3 Geostrophic Fine Scales.- 5.2.4 Surface Layer Mesoscale Eddies.- 5.2.5 The General Circulation.- 5.3 The Experiment.- 5.4 The Phenomena.- 5.5 Summary.- 6. Gulf Stream Variability.- 6.1 Introduction.- 6.2 The Gulf Stream Path.- 6.3 Current Structure and Transport.- 6.4 Water Masses.- 6.5 Dynamics.- 6.6 Summary.- 7. The Northeast Atlantic Ocean.- 7.1 Introduction.- 7.2 General Oceanographic Conditions and Mean Circulation..- 7.3 Data Sources.- 7.3.1 Hydrographic Data.- 7.4 XBT Observations.- 7.5 Direct Observation of Currents.- 7.6 Satellite Observations.- 7.7 Surveys of Individual Eddies.- 7.8 Summary.- 8. Eddy Structure of the North Pacific Ocean.- 8.1 Introduction.- 8.2 Coastal Regions.- 8.3 Mid-Latitude Open Ocean.- 8.4 Tropical Region.- 8.5 Direct Current Measurements.- 9. Subpolar Gyres and the Arctic Ocean.- 9.1 Introduction.- 9.2 The Arctic Ocean.- 9.3 Labrador Sea and Northwestern Atlantic.- 9.4 The Norwegian and Greenland Seas and Their Overflows.- 9.5 The Northeast North Pacific and Bering Sea.- 9.6 Summary.- 10. Tropical Equatorial Regions.- 10.1 Latitudinal Changes of Mesoscale Processes.- 10.2 Eddy-Resolving Arrays in the Tropics.- 10.3 Mesoscale Features in Sections.- 10.4 Mesoscale Energy in the Tropics.- 11. Eddies in the Indian Ocean.- 11.1 Introduction.- 11.2 Kinetic Energy of the Seasonal Circulation.- 11.3 Arabian Sea.- 11.4 Somali Current.- 11.5 Bay of Bengal.- 11.6 Equatorial Zone.- 11.7 South Equatorial Current.- 11.8 Deep Currents in the Indian Ocean.- 11.9 Significance of Indian Ocean Eddies.- 12. The South Pacific Including the East Australian Current.- 12.1 Introduction: The Subtropical South Pacific.- 12.2 Observations: The Tasman Sea.- 12.2.1 The East Australian Current.- 12.2.2 The Tasman Front.- 12.3 Theories.- 12.3.1 A Line Vortex and a Wall.- 12.3.2 A Free Inertial Jet.- 12.3.3 Baroclinic Instability of a Western Boundary Flow..- 12.4 The Significance of Eddies.- 12.4.1 Physical Significance.- 12.4.2 Biological Significance.- 12.5 Future Research.- 12.5.1 The Mid-Ocean.- 12.5.2 The East Australian Current.- 13. Eddies in the Southern Indian Ocean and Agulhas Current.- 13.1 Introduction.- 13.2 South Eastern Indian Ocean.- 13.2.1 Vicinity of the South Equatorial Current.- 13.2.2 West of Australia.- 13.2.3 Vicinity of the Subtropical Convergence.- 13.3 South Western Indian Ocean.- 13.3.1 Eddies South of Madagascar.- 13.3.2 Larger Southwestern Indian Ocean.- 13.3.3 Adjacent to the Agulhas Current.- 13.3.4 The Agulhas Retroflection Area.- 13.3.5 The Vicinity of the Agulhas Plateau.- 13.4 Discussion.- 14. The Southern Ocean.- 14.1 Introduction.- 14.2 Observations of Eddies in the Southern Ocean.- 14.3 Eddy Generation and Decay.- 14.4 Effects Eddies and Implications for Models the Southern Ocean.- 15. Global Summaries and Intercomparisons: Flow Statistics from Long-Term Current Meter Moorings.- 15.1 Introduction.- 15.2 Global Kinetic Energy Estimates from Shift-Drift Analysis.- 15.3 The North Atlantic.- 15.3.1 Introduction.- 15.3.2 Ocean-Scale Patterns of Kinetic Energy.- 15.3.3 A Transect of the Western Basin.- 15.3.4 A Transect of the Eastern Basin.- 15.4 The North Pacific.- 15.4.1 The Kuroshio.- 15.4.2 Western Pacific.- 15.4.3 East-Central Pacific.- 15.4.4 Central and Eastern Tropical Pacific.- 15.5 The Equatorial Zone.- 15.6 South Atlantic.- 15.7 High Latitudes.- 15.7.1 The Antartic Circompolar Current.- 15.7.2 Weddell Sea.- 15.7.3 The West Spitsbergen Current.- 15.7.4 Arctic Ocean.- 15.8 Summary.- 15.8.1 Horizontal Distribution of Eddy Kinetic Energy at Midlatitudes.- 15.8.2 Vertical Structure of the Eddy Field at Midlatitudes.- 15.8.3 Vertical Eddy Structure in Ice-Covered Seas.- 15.8.4 Eddy Time Scales at Midlatitudes.- 15.8.5 Eddy Time Scales in the Equatorial Zone.- 15.8.6 Relationship of KE to KM Worldwide.- 16. Global Summary: Review of Eddy Phenomena as expressed in Temperature Measurements.- 16.1 Introduction.- 16.2 Standard Deviation of Temperature.- 16.3 The North and Equatorial Atlantic.- 16.4 The North and Equatorial Pacific.- 16.5 Discussion.- Models.- 17. Eddy-Resolving Numerical Models of Large-Scale Ocean Circulation.- 17.1 Introduction.- 17.2 Review of EGCM Results.- 17.2.1 What Processes Account for the Presence of Mesoscale Variability?.- 17.2.2 Do Mesoscale Phenomena Play a Fundamental Role in the Character and Dynamics of the Time-Mean Circulation?.- 17.2.3 Where the Effects of Mesoscale Circulations Are Important, Can They Be Parametrized in Terms of Mean-Field Quantities?.- 17.2.4 How Do the Answers to Questions About the Role of Mesoscale Eddies Change as the Model Physical Processes Change?.- 17.3 Comparisons with Observations.- 17.4 Unsolved Problems and Future Prospects.- 18. Periodic and Regional Models.- 18.1 Introduction.- 18.2 Two-Dimensional Turbulence.- 18.3 The Effects of ?.- 18.4 Mean Flow Generation by Localized Forcing.- 18.5 Turbulent Cascades in a Stratified Fluid.- 18.6 Scattering by Topography.- 18.7 Regional Models and Non-Local Effects.- 18.8 Comparison with Observations.- 18.9 Conclusions and Future Directions.- Effects and Applications.- 19. Eddies in Relation to Climate.- 19.1 Introduction.- 19.2 Heat Flux Carried by Eddies.- 19.3 Indirect Effects of Eddies on the Heat Balance.- 20. Eddies and Coastal Interactions.- 20.1 Introduction.- 20.2 Theoretical Considerations.- 20.2.1 Stratification, P-Effect.- 20.2.2 Abrupt Topography: Scattering and Reflection.- 20.2.3 Refractive Effects.- 20.2.4 Bottom Friction.- 20.2.5 Longshore Currents.- 20.2.6 Generating Mechanisms and Initial Value Problems.- 20.3 Observations and Analysis.- 20.3.1 The New England Continental Rise.- 20.3.2 The East Australian Shelf.- 20.3.3 The Southeastern Coast of the U.S.- 20.3.4 The West Florida Shelf.- 20.3.5 The Scotian Shelf.- 20.4 Anatomy of a Warm-Core Ring Interaction with the Continental Margin.- 20.4.1 Low-Frequency Current Data, Summer 1976.- 20.4.2 Offshore Forcing.- 20.4.3 Analysis and Interpretation.- 20.5 Conclusions.- 21. Eddy-Induced Dispersion and Mixing.- 21.1 Introduction.- 21.2 Two-Dimensional Dispersal in the Mid-Ocean.- 21.3 Streakiness.- 21.4 Particle Motions.- 21.5 Gyre-Scale Dispersal Effects.- 21.6 Tracer Evidence for Dispersal Processes.- 22. Eddies and Biological Processes.- 22.1 Introduction.- 22.2 Frontal Eddies.- 22.2.1 Formation.- 22.2.2 Air-Sea Interaction Within a Ring.- 22.2.3 Horizontal Exchanges Between the Ring and Its Surroundings.- 22.2.4 Horizontal Exchange of Plankton Between a Ring and Its Surrounding Water.- 22.3 Mid-Ocean Eddies.- 22.3.1 Biological Processes in a Single Eddy.- 22.3.2 Spatial Spectrum.- 22.4 Observational Data.- 22.4.1 Scripps Transects.- 22.4.2 Gulf Stream Ring Structures.- 22.4.3 East Australian Current Rings.- 22.4.4 Incidental Observations.- 22.5 Sampling Procedures.- 22.6 Conclusions.- 23. Eddies and Acoustics.- 23.1 Introduction.- 23.2 Dynamic Ocean.- 23.3 Sound Propagation in a Range-Dependent Environment.- 23.3.1 Geometrical Acoustics.- 23.3.2 Normal Modes.- 23.3.3 The Parabolic Approximation.- 23.4 Analytical and Numerical Studies of Sound Propagation Through Eddies.- 23.5 Acoustic Measurements in Eddies.- 23.6 Acoustic Eddy Monitoring.- 23.7 Conclusions.- 24. Instruments and Methods.- 24.1 Introduction.- 24.2 Moored Instrumentation.- 24.2.1 Moorings.- 24.2.2 Fixed Depth Moored Current Meters.- 24.3 Moored Profiling Current Meters.- 24.4 Temperature Recorders.- 24.5 Other Moored Instrumentation.- 24.6 Drifting Instruments.- 24.6.1 Surface Drifters.- 24.6.2 Deep Drifters.- 24.6.3 Problems and Interpretations.- 24.7 Profiling Instruments.- 24.7.1 Temperature and Salinity Instruments.- 24.7.2 Nansen Bottles.- 24.7.3 CTD and STD.- 24.8 Expendable Bathythermographs.- 24.9 Current Profilers.- 24.9.1 Electromagnetic Velocity Profiler.- 24.9.2 The White Horse.- 24.9.3 Schmitz-Richardson Profiler.- 24.9.4 Other Velocity Profilers.- 24.9.5 Calibration and Intercomparison.- 24.10 Remote and Inverse Techniques.- 24.10.1 Satellite and Airborne Measurements.- 24.10.2 Tomography.- 24.11 Intercomparison Between Instrument Types.- References.