Ocean currents: physical drivers in a changing world

Front Matter
Copyright
Contents
Acknowledgements
1 The restless ocean
Chapter Outline
Ten big questions
Organization vs. chaos
Measuring the ocean-Challenges and international organization
Measuring ocean currents
Drift measurements
Point measurements
Profile measurements
Radar measurements
Estimating ocean currents
Hydrography
Bottom pressure recorders
Satellite altimeters
Electrical cables
Computer simulation of ocean currents
An ocean of scales
Summary
2 Frameworks, data, and methods
Chapter Outline
Essential physics and scalar conservation
Seawater properties, the equation of state, and neutral surfaces
Conservation of mass, salt, and heat
Essential dynamics-With the flow and at a fixed point
Real forces
The effects of Earth's rotation
The equations of motion-Following the flow
Advection of momentum
The equations of motion-At a fixed point
Scaling arguments and approximating the equations of motion
Ocean and climate data products
Ocean observations (Argo)
Ocean reanalysis (GODAS)
Ocean analysis (EN4)
Air-sea fluxes (COREv2)
Atmospheric reanalysis (NCEP/NCAR)
Tropical cyclone tracks (IBTRaCS; HURDAT)
Sea ice (NSIDC) and icebergs (IIP; BYU/NIC)
Numerical models of the ocean and climate
Governing equations and approximations
Numerical solution
Meshes, grids, and vertical coordinates
Resolution, processes, and parameterizations
From bespoke to community codes
Coupling, complexity, and climate
Particle tracking
Resourcing Chapters 3-1234567891012
Exercises
References
3 Surface drift, gyres, and the fate of plastic
Chapter Outline
Large scales in space and time
The restless atmosphere
A moist thermodynamic heat engine-Basics
Large-scale wind patterns
Local response to wind-Surface drift
Wind stress
The inertial response to a wind impulse
Balancing forces at the surface
Balancing forces sub-surface
Large-scale consequences
Basin-scale response-The great gyres
The wind-driven circulation and vorticity
Opposing vorticity tendencies
Horizontal pressure gradients and sea surface slopes
Gyre circulation and Ekman currents-The combined surface drift
Additional influences on surface and near-surface drift
Examples of surface drift at basin scale
Sargassum seaweed in the Sargasso Sea
Subsea volcanic eruptions and pumice rafts
Tsunami debris and container spills
The fate of plastics in the World Ocean
References
4 Western boundary currents and drifting organisms
Chapter Outline
Mapping and characterizing western boundary currents
Local force balance
Sea surface slopes
Horizontal density gradients
Estimating geostrophic currents
Basin-scale force balance
Conservation of absolute vorticity in the interior of a subtropical gyre
Balancing vorticity at the western boundary
Vorticity tendencies around a subtropical gyre
Leaving the boundary behind
Drift through western boundary current systems-Particle trajectories, ensemble statistics, and ecological consequences
The enigmatic first year in the life of sea turtles-Finding Nemo in NEMO
Tracing the fate and source of the Gulf Stream
Separation and retroflection
Vertical shear in western boundary currents and vertical motion along trajectories
Transports associated with western boundary currents
Hydrographic changes along western boundary current trajectories
Nutrient streams and wider biogeochemical contexts
Temperature-sensitive microbial ecology
References
5 Eastern boundary currents, upwelling, and high biological productivity
Chapter Outline
Mapping and characterizing EBC systems
Eastern boundaries in the subtropics-The `Big Four upwelling systems
The Leeuwin Current-An exception to the rule in the subtropics
Eastern boundaries in subpolar latitudes
Ekman dynamics in the presence of a coast
Geostrophy in the presence of topography
Slope currents
Drift along and across eastern boundary current systems-3D water parcel trajectories and the ecological consequences
The source of upwelled water, nutrients, and productivity
Sources of the European Slope Current and downstream influences on North Sea ecosystems
References
6 The tropical oceans, interannual climate variability, and ecosystem adaptation
Chapter Outline
Mapping and characterizing currents near the Equator
The Pacific
The Atlantic
The Indian Ocean
Ekman dynamics near the Equator
Tropical variability
Planetary waves near the Equator
El Niño and the Southern Oscillation
Tropical Instability Waves
Drift in the tropics-2D water parcel trajectories and some ecological consequences
Dispersal of coral spores and connectivity throughout the tropics
Re-visiting pumice drift-An eruption in the tropical South Pacific
Adaptation of sea turtles to tropical ocean currents
The Sargassum Crisis in the Atlantic
Tropical ocean circulation and climate variability
Recent ENSO variability and associated teleconnections
Variable Atlantic hurricane seasons
Western Indian Ocean warming and the South Asian Monsoon
References
7 From the northern subpolar oceans to the Arctic and its retreating sea ice
Chapter Outline
The northern cryosphere
Sea ice
Glacial ice
The atmosphere at mid and high latitudes
The jet stream
The stratospheric polar vortex (SPV)
The North Atlantic Oscillation (NAO) and the Arctic Oscillation (AO)
Greenland tip jets and intense air-sea interaction
Water masses of subpolar and high latitudes
Mode waters
Intermediate waters
Dense waters
Ocean circulation at subpolar and high latitudes
The subpolar North Atlantic and water mass transformation
The Greenland-Iceland-Norwegian Seas
The Arctic
The deep circulation
Variability and long-term change
Variability and recent events across the subpolar North Atlantic
Greenland mass imbalance and peripheral seas
The changing Arctic
References
8 From the Southern Ocean to Antarctica and its changing ice shelves
Chapter Outline
The southern cryosphere
Sea ice
Glacial ice
The atmosphere at southern high latitudes
Mid-latitude atmospheric circulation and the Roaring Forties
High latitude atmospheric circulation and the Southern Polar Vortex
Katabatic winds
The Southern Annular Mode
Air-sea exchanges of heat and freshwater
Water masses of the Southern Ocean and around Antarctica
Mode Waters and Intermediate Waters
Dense water preconditioning around Antarctica
Abyssal and Deep Waters
Surface and deep-reaching currents
Ekman currents in the Southern Ocean
The Antarctic Circumpolar Current (ACC)
Fronts, jets, and eddies
The subpolar gyres
Coastal and slope currents around Antarctica
Meridional overturning cells and sensitivity of the 3D circulation to wind forcing
The upper limb and CDW upwelling
The lower limb and AABW export
Sensitivity of the 3D circulation to wind forcing
Modelling the Southern Ocean-A brief history and the status quo
Applied contexts
Microplastics reaching the Southern Ocean and consequences for seabirds
Plastics reaching Antarctic waters
Ecological pathways to Antarctica
Natural and artificial iron fertilization
Heat and carbon uptake in the Southern Ocean
Interaction of warming ocean with Antarctic ice shelves and global sea level rise
9 Processes and flows in marginal seas
Chapter Outline
Processes in marginal seas
Turbulence and mixing
Tides
Seasonal stratification
Tidal mixing fronts and residual circulation
Runoff and freshwater
Exchanges
Summary of processes
Deep or isolated marginal seas
The Mediterranean and Black Seas
Red Sea and Persian Gulf
Japan and Okhotsk Seas
The Indonesian Seas
Caribbean Sea and Gulf of Mexico
Shelf seas
Northwest European shelf
China Seas
Sunda and Sahul shelves
Northeast US and east Canadian seaboard
Patagonian shelf
High-latitude shelf seas
Freshwater influences
Equatorial Atlantic
East Asia
Northwest Europe
Biological productivity and pollution in marginal seas
Primary productivity in shelf seas and at shelf breaks
Microplastic drift through coastal and shelf seas
References
10 Ocean boundaries, connectivity, and inter-ocean exchanges
Chapter Outline
Defining an ocean basin
Surface connectivity
Upper-ocean connectivity and inter-ocean exchanges
Fronts as demarcation lines
Coherent structures and marine biogeography
Re-defining an ocean basin
References
11 The global circulation and transformation of water masses
Chapter Outline
Piecing together a global circulation
The near-surface circulation
The sub-surface circulation
The 3D global circulation
Meridional overturning cells, forcing, and energetics
Pole-to-pole overturning - The holistic perspective
Boundary forcing - The thermohaline perspective
Pushing and pulling the MOC - The energetics perspective
Global trajectories and pathways of water parcels
Re-thinking circulation in property space
Surface density fluxes
Diapycnal density fluxes
The surface water mass transformation rate
Interior water mass transformation
Linking the circulation and transformation of water masses
Surface-forced overturning
The global thermohaline circulation in temperature and salinity space
References
12 Ocean currents, heat transport, and climate
Chapter Outline
Meridional heat transport by the AMOC and north European warmth
Variability of the large-scale ocean circulation and regional climate
Tracing the global overturning in changing property distributions
Abrupt climate change in the past-A warning for the future
References
Epilogue: Looking ahead
Unfolding changes in ocean currents
Emerging technologies
Opportunities and solutions
References
Index